Peer-Reviewed Publications

Mishra, S., J. Dee, W. Moar, J. Dufner-Beattie, J. Baum, N. P. Dias, A. Alyokhin, A. Buzza, S.I. Rondon, M. Clough, and S. Menasha. 2021. Selection for high levels of resistance to double-stranded RNA (dsRNA) in Colorado potato beetle (Leptinotarsa decemlineata Say) using non-transgenic foliar delivery. Scientific Reports 11 (2021): 6523. https://doi.org/10.1038/s41598-021-85876-1
Insecticidal double-stranded RNAs (dsRNAs) silence expression of vital genes by activating the RNA interference (RNAi) mechanism in insect cells. Despite high commercial interest in insecticidal dsRNA, information on resistance to dsRNA is scarce, particularly for dsRNA products with non-transgenic delivery (ex. foliar/topical application) nearing regulatory review. We report the development of the CEAS 300 population of Colorado potato beetle (Leptinotarsa decemlineata Say) (Coleoptera: Chrysomelidae) with > 11,100-fold resistance to a dsRNA targeting the V-ATPase subunit A gene after nine episodes of selection using non-transgenic delivery by foliar coating. Resistance was associated with lack of target gene down-regulation in CEAS 300 larvae and cross-resistance to another dsRNA target (COPI â; Coatomer subunit beta). In contrast, CEAS 300 larvae showed very low (~ 4-fold) reduced susceptibility to the Cry3Aa insecticidal protein from Bacillus thuringiensis. Resistance to dsRNA in CEAS 300 is transmitted as an autosomal recessive trait and is polygenic. These data represent the first documented case of resistance in an insect pest with high pesticide resistance potential using dsRNA delivered through non-transgenic techniques. Information on the genetics of resistance and availability of dsRNA-resistant L. decemlineata guide the design of resistance management tools and allow research to identify resistance alleles and estimate resistance risks.

Klein, C., M. Baker, A. Alyokhin, and D. Mota-Sanchez. 2021. Geographic variation in dominance of spinosad resistance in Colorado potato beetles (Coleoptera: Chrysomelidae). Journal of Economic Entomology 114: 320-325.
Eastern New York State is frequently the site of Colorado potato beetle (Leptinotarsa decemlineata, Say) populations with the highest observed levels of insecticide resistance to a range of active ingredients. The dominance of a resistant phenotype will affect its rate of increase and the potential for management. On organic farms on Long Island, L. decemlineata evolved high levels of resistance to spinosad in a short period of time and that resistance has spread across the eastern part of the Island. Resistance has also emerged in other parts of the country as well. To clarify the level of dominance or recessiveness of spinosad resistance in different parts of the United States and how resistance differs in separate beetle populations, we sampled in 2010 beetle populations from Maine, Michigan, and Long Island. In addition, a highly resistant Long Island population was assessed in 2012. All populations were hybridized with a laboratory-susceptible strain to determine dominance. None of the populations sampled in 2010 were significantly different from additive resistance, but the Long Island population sampled in 2012 was not significantly different from fully recessive. Recessive inheritance of high-level resistance may help manage its increase.

Alyokhin, A. and N. Baron. 2021. Increased cannibalism in Colorado potato beetles feeding on non-preferred host plants in laboratory. Entomologia Experimentalis et Applicata 169: 249-254. (Editor's Choice paper)
Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), is an oligophagous herbivore that feeds on several plant species in the family Solanaceae. Cannibalism is common in this species and accounts for a significant part of natural field mortality.We investigated effects of feeding on potato (Solanum tuberosum L., preferred host), tomato (Solanum lycopersicum L., nonpreferred host), and pothos [Epipremnum aureum (Linden & Andr.e) Bunting (Araceae), non-host] leaves on the incidence of adult Colorado potato beetles predating each other. After 48 h of confinement in laboratory arenas, significantly higher cannibalism was observed in the absence of host vegetation than in the presence of either potato or tomato leaves. After 72 h, more beetles were attacked when kept on tomato leaves than on potato leaves. Being confined on non-host pothos leaves led to higher cannibalism compared to either species of host plant. However, its incidence was lower compared to the no-leaf treatment, probably because pothos leaves served as a source of water. Our results suggest that adult cannibalism in the Colorado potato beetle may be triggered by a relatively mild adversity, but its extent increases as conditions deteriorate.

Jasim, A., A. Zaeen, L. K. Sharma, S. K. Bali, C. Wang, A. Buzza, and A. Alyokhin. 2020. Predicting phosphorus and potato yield using active and passive sensors. Agriculture 2020, 10, 564. https://doi.org/10.3390/agriculture10110564
Applications of remote sensing are important in improving potato production through the broader adoption of precision agriculture. This technology could be useful in decreasing the potential contamination of soil and water due to the over-fertilization of agriculture crops. The objective of this study was to assess the utility of active sensors (Crop Circle™, Holland Scientific, Inc., Lincoln, NE, USA and GreenSeeker™, Trimble Navigation Limited, Sunnyvale, CA, USA) and passive sensors (multispectral imaging with Unmanned Arial Vehicles (UAVs)) to predict total potato yield and phosphorus (P) uptake. The experimental design was a randomized complete block with four replications and six P treatments, ranging from 0 to 280 kg P ha-1, as triple superphosphate (46% P2O5). Vegetation indices (VIs) and plant pigment levels were calculated at various time points during the potato growth cycle, correlated with total potato yields and P uptake by the stepwise fitting of multiple linear regression models. Data generated by Crop Circle™ and GreenSeeker™ had a low predictive value of potato yields, especially early in the season. Crop Circle™ performed better than GreenSeeker™ in predicting plant P uptake. In contrast, the passive sensor data provided good estimates of total yields early in the season but had a poor correlation with P uptake. The combined use of active and passive sensors presents an opportunity for better P management in potatoes.

Zaeen, A. A., L. Sharma, A. Jasim, S. Bali, A. Buzza, and A. Alyokhin. 2020. Yield and quality of three potato cultivars under series of nitrogen rates. Agrosystems, Geosciences, and Environment 2020;3:e20062. https://doi.org/10.1002/agg2.20062
Undesirable growth of potato (Solanum tuberosum L.) crop under an excessive N fertilizer application is a potentially serious problem. This research was conducted to investigate the response of different potato cultivars; Russet Burbank, Shepody, and Superior, and its qualitative characteristics under a series of N rates. Six rates of N fertilization (0–280 kg ha-1) were applied on 11 sites in a randomized complete block design, with four replications. Sites with =30 g kg-1 of soil organic matter (OM) produced total tuber yield, marketable yield, and tuber weight per plant 39.5, 45.2, and 54.9%, respectively, higher than sites with =30 g kg-1 of OM. Tubers specific gravity increased by 0.18% in the sites with =30 g kg-1 of OM. The total tuber yield for the three cultivars was maximized at 168 kg N ha-1. Marketable specific gravity, starch, and dry matter content were achieved by applying 168 and 112 kg N ha-1 at =30 and =30 g kg-1 of OM sites, respectively. Russet Burbank produced a higher yield than Shepody and Superior cultivars significantly, but there was no significant difference among them regarding specific gravity. Excessive N application (>168 kg ha-1) decreased potato tuber production and quality.

Erbland, P., S. Caron, M. Peterson, and A. Alyokhin. 2020. Design and performance of a low-cost, automated, large-scale photobioreactor for microalgae production. Aquacultural Engineering 90 (2020) 102103 https://doi.org/10.1016/j.aquaeng.2020.102103.
Microalgae feed production is a major cost in bivalve aquaculture. Its efficiency is increased by scaling it up under automated control of environmental conditions. The initial cost of commercially available systems can be prohibitive. Therefore, a large volume full-scale photobioreactor built of low-cost, readily available materials was developed and tested. A cone-bottom, polyethylene tank was internally illuminated with submersible fluorescent lamps and equipped with a monitoring and control system that measured temperature, pH and optical density of the microalgal culture. Injection of CO2 was automated to maintain pH within a target range. System performance was evaluated by growing four batch cultures of Tetraselmis chuii. Temperature inside the photobioreactor was 29.5?±?2.38 °C (mean?±?SD, range 21-35?°C) and pH was 7.56?±?0.87 (mean?±?SD, range 5.29–8.97). Optimal harvest time was after 300?h (12.5 days) of growth, yielding 1700?L of microalgae at a density of 2500 cells/ µl (1200 cells/ µl/ m2 illuminated surface area). With 24?h illumination, the fluorescent lights, air pump and monitoring/ control device consumed 14.9, 1.9 and 0.1kwh/ day, respectively. Assuming the microalgae are harvested at their optimal density after 12.5 days, each batch would consume 211kwh or 0.124kwh/ liter. The photobioreactor described provides an economical option for growing large amounts of microalgae for aquaculture feed and other purposes.

Jasim, A., L. K. Sharma, A. Zaeen, S. K. Bali, A. Buzza, and A. Alyokhin. 2020. Potato phosphorus response in soils with high value of phosphorus. Agriculture 2020, 10, 264; doi:10.3390/agriculture10070264.
< 6 had total tuber yields, marketable tuber yields, tuber numbers per plant, and total tuber mean weights that were all higher than these same parameters at sites with soil pH = 6. All sites with soil pH< 6 showed a highly correlated relationship between P uptake and petiole dry weight (R2 = 0.76). The P application rate of 56 kg P ha-1 was the best at sites with a soil pH < 6, but 0–56 kg P ha-1 was the best at sites with soil pH = 6.

Erbland, P. A. Alyokhin, L. B. Perkins, and M. Peterson. 2020. Dose-dependent retention of omega-3 fatty acids by black soldier fly larvae (Diptera: Stratiomyidae). Journal of Economic Entomology, 113: 1221-1226.
Black soldier fly larvae, Hermetia illucens (L.), are used to convert organic waste streams into insect-based animal feeds. We tested their ability to retain alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) from feeding substrates, which has important implications for their use in aquaculture. When supplementing a chicken feed diet with increasing concentrations of salmon oil (0–42%) over an increasing number of days (0–8), the concentrations of the three omega-3 acids in larvae increased significantly. Larval survival and biomass accumulation were not affected. Supplementing a chicken feed diet with increasing concentrations (0–14%) of Tetraselmis chui Butcher (Chlorodendrales: Chlorodendraceae) microalgae paste also significantly increased ALA and EPA contents of the harvested larvae. However, microalgae also decreased survival, harvested biomass, and individual growth of larvae feeding on the diet with the highest supplement concentration (14%). DHA was not detected in any microalgae diet or subsequent larval tissue samples. All three omega-3 polyunsaturated fatty acids tested in this study were accumulated in dose-dependent manner, with quadratic, and occasionally linear, equations providing the best description of the observed relationships. There were significant negative correlations between several fatty acids, indicating that they may replace one another in living larvae. Our findings confirm that black soldier fly larvae can retain ingested fatty acids and change fatty acid profiles in their tissues accordingly. However, optimizing nutrient content of harvestable larvae is likely to be more complicated than simply enriching their diets with omega-3 fatty acids.

Alyokhin, A., B. Nault, and B. Brown. 2020. Soil conservation practices for insect pest management in highly disturbed agroecosystems - a review. Entomologia Experimentalis et Applicata 168: 7-27.
Decline in soil health is a serious worldwide problem that decreases complexity and stability of agricultural ecosystems, commonly making them more prone to outbreaks of herbivorous insect pests. Potato (Solanum tuberosum L., Solanaceae) and onion (Allium cepa L., Amaryllidaceae) production is currently characterized by high soil disturbance and heavy reliance on synthetic inputs, including insecticides. Evidence suggests that adopting soil conservation techniques often (but not always) increases mortality and decreases reproductive output for the major insect pests of these important vegetable crops. Known mechanisms responsible for such an effect include increases in density and activity of natural enemy populations, enhanced plant defenses, and modified physical characteristics of respective agricultural habitats. However, most research efforts focused on mulches and organic soil amendments, with additional research needed on elucidating effects and their mechanisms for conservation tillage, cover crops, and arbuscular mycorrhizae.

Zaeen, A. A., L. Sharma, A. Jasim, S. Bali, A. Buzza, and A. Alyokhin. 2020. In-season potato yield prediction with active optical sensors. Agrosystems, Geosciences, and Environment 2020;3:e20024. https://doi.org/10.1002/agg2.20024
Crop yield prediction is a critical measurement, especially in the time when parts of the world are suffering from farming issues. Yield forecasting gives an alert regarding economic trading, food production monitoring, and global food security. This research was conducted to investigate whether active optical sensors could be utilized for potato (Solanum tuberosum L.) yield prediction at the mid.le of the growing season. Three potato cultivars (Russet Burbank, Superior, and Shepody) were planted and six rates of N (0, 56, 112, 168, 224, and 280 kg ha-1), ammonium sulfate, which was replaced by ammonium nitrate in the 2nd year, were applied on 11 sites in a randomized complete block design, with four replications. Normalized difference vegetation index (NDVI) and chlorophyll index (CI) measurements were obtained weekly from the active optical sensors, GreenSeeker (GS) and Crop Circle (CC). The 168 kg N ha-1 produced the maximum potato yield. Indices measurements obtained at the 16th and 20th leaf growth stages were significantly correlated with tuber yield. Multiple regression analysis (potato yield as a dependent variable and vegetation indices, NDVI and CI, as independent variables) could make a remarkable improvement to the accuracy of the prediction model and increase the determination coefficient. The exponential and linear models showed a better fit of the data. Soil organic matter content increased the yield significantly but did not affect the prediction models. The 18th and 20th leaf growth stages are the best time to use the sensors for yield prediction.

Bernard, E., J. Villazana, A. Alyokhin, and J. Rose. 2020. Colonization of finfish substrate inhabited by black soldier fly larvae by blow flies, bacteria, and fungi. Journal of Insects as Food and Feed 6: 291-304.
Black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae) can be used for recycling a wide variety of organic wastes. However, these wastes are also suitable for colonisation by pest fly species, including the blow fly Lucilia sericata (Meigen) (Diptera: Calliphoridae), and by pathogenic microorganisms. We tested effects of the presence of black soldier fly larvae (BSFL) on recruitment and retention of blow fly larvae, as well as on composition and dynamics of microbial communities in finfish-based substrates. Substrates inhabited by BSFL contained approximately one-tenth of the L. sericata pupae found in the control substrate even when BSFL were removed prior to the introduction of gravid L. sericata females. Furthermore, almost three-quarters of L. sericata released into substrates previously colonised by BSFL emigrated within 24 h, while no such emigration was detected for the control substrates. Unlike previous studies, bacterial community was heavily dominated by Gram-positive species. Overall bacterial abundance on BSFL substrates declined approximately two-fold compared to the control substrate, while fungal abundance increased. However, surviving microbial communities were still robust and diverse, and continued to be dominated by Gram-positive bacteria. On the other hand, Gram-negative Shigella sonnei, which is a common cause of diarrhoea in humans, was more than 200 times less abundant in BSFL substrates compared to the control throughout the experiment. Repellent and antibiotic properties observed in this study are advantageous for using BSFL in remediation of finfish wastes. However, additional treatment of remaining residue may still be necessary to eliminate all biological contamination.

Galimberti, A., A. Alyokhin, H. Qu, and J. Rose. 2020. Simulation modelling of Potato virus Y spread in relation to initial inoculum and vector activity. Journal of Integrative Agriculture 19: 376-388.
Potato virus Y (PVY) is a non-persistent virus that is transmitted by many aphid species and causes significant damage to potato production. We constructed a spatially-explicit model simulating PVY spread in a potato field and used it to investigate possible effects of transmission efficiency, initial inoculum levels, vector behavior, vector abundance, and timing of peak vector activity on PVY incidence at the end of a simulated growing season. Lower PVY incidence in planted seed resulted in lower virus infection at the end of the season. However, when populations of efficient PVY vectors were high, significant PVY spread occurred even when initial virus inoculum was low. Non-colonizing aphids were more important for PVY spread compared to colonizing aphids, particularly at high densities. An early-season peak in the numbers of noncolonizing aphids resulted in the highest number of infected plants in the end of the season, while mid- and late-season peaks caused relatively little virus spread. Our results highlight the importance of integrating different techniques to prevent the number of PVY-infected plants from exceeding economically acceptable levels instead of trying to control aphids within potato fields. Such management plans should be implemented very early in a growing season.

Popov, S. Ya. and A. Alyokhin. 2019. Gender-specific acaricidal properties and sexual transmission of spirotetramat in two-spotted spider mite (Tetranychidae: Acariformes). Journal of Economic Entomology 112: 2186-2192.
Two-spotted spider mite, Tetranychus urticae Koch (Tetranychidae: Acariformes), is one of the most important agricultural pests in the world. Their populations have a tendency of rapidly developing resistance to acaricides, making it necessary to have a variety of active ingredients for sustainable chemical control of this pest. We investigated acaricidal properties of a relatively new insecticide spirotetramat using its commercial formulation, Movento Energy. Spirotetramat applied at concentrations equivalent to the field rates of 78 and 90 g ai/ha had a strong negative effect on the survival of the treated T. urticae, with ca. 95% of females and ca. 65% of males dying after the treatment. Spirotetramat appeared to interfere with female reproductive system. Many of the dead treated females had eggs stuck in the oviduct and protruding from their bodies. Surviving treated females did not lay eggs. Furthermore, untreated females that mated with treated males did not produce female offspring and displayed the symptoms of spirotetramat poisoning. Toxic effects continued manifesting themselves after female mites were transferred from treated onto untreated plant culture. Contrary to previous studies, contact toxicity was also detected. None of the treated immature stages survived to adulthood. Based on these results, spirotetramat may be a good option for integrated pest management in crops that are simultaneously affected by sucking insects and spider mites and in pesticide rotation sequences that are a part of integrated resistance management programs.

Villazana, J. and A. Alyokhin. 2019. Development of black soldier fly larvae (Diptera: Stratiomyidae) on seafood wastes. Journal of Insects as Food and Feed 5: 313-319.
The black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae) is well suited for remediating biological waste. Larvae of this species are nutrient rich, grow rapidly, and convert organic wastes while suppressing pathogens and pests. Therefore, they could be used in waste management systems and as feed for livestock and in aquaculture. The goal of this study was to test suitability of several seafood wastes from Maine processing facilities for H. illucens development in order to find alternative venues for their utilization. The following substrates were tested under laboratory conditions: dry sea cucumber, wet sea cucumber, crab meal, finfish, dry quahog, wet quahog, and sea urchin (‘wet’ and ‘dry’ refer to the original condition of the wastes while their moisture levels were similar during the experiment). H. illucens eggs were placed on wax paper above each substrate, and larval growth and survival to pupation were measured. Based on the numbers and weights of surviving larvae, substrates potentially suitable for H. illucens rearing included finfish trimmings, wet sea cucumber, dry quahog, and sea urchin. Crab meal produced large larvae (0.091±0.021 g [mean ± SE], compared to experiment-wide mean of 0.064±0.007 g) in a relatively short period of time. However, larval mortality was very high, with only 4.7±1.17 larvae surviving to prepupae, compared to experiment-wide mean of 9.78±0.63 larvae. There were dramatic differences in seemingly similar materials. On wet sea cucumber, 28.82±1.49 larvae per replication survived to pre-pupae, while on dry sea cucumber the number was only 0.33±0.01. On wet and dry quahog, the numbers of surviving larvae were 1.83±0.60 and 10.1±1.97, respectively. This highlights the importance of thorough testing of specific substrates instead of extrapolating from published data.

Villazana, J. and A. Alyokhin. 2019. Tolerance of immature black soldier flies (Diptera: Stratiomyidae) to cold temperatures above and below freezing point. Journal of Economic Entomology 112: 2632-2637.
Black soldier flies, Hermetia illucens (L.), consume decaying organic materials at the larval stage and can be used for recycling a variety of biogenic wastes into value-added products. Black soldier flies are normally found in subtropical and warm temperate regions. Cold temperatures may prevent their establishment in colder areas, thus alleviating a concern of their becoming an invasive species. Potentially, cold temperatures can also be used to manipulate the rate of black soldier fly development, which may be needed for timing certain life stages for mass-production needs. In the present study, immature black soldier flies were highly susceptible to freezing. Their survivorship decreased as time spent at ?12°C increased from 10 to 60 min. Only ca. 2% of eggs, less than 1% of larvae, and no pupae survived after 60 min of exposure. Chilling at 4°C also had a significant negative effect that became more pronounced as duration of exposure increased from 24 to 72 h. Only ca. 2% of eggs and second instars and ca. 23% of pupae survived after 72 h. In the same time, more than 80% of third instars and more than 90% of fifth instars were still alive following 72 h of exposure. Chilling fifth instars resulted in smaller adults but freezing them for 48 h resulted in bigger adults. Based on these results, black soldier fly is unlikely to establish in areas with long periods of subfreezing winter temperatures. Low temperatures may be used to manipulate development of the late instars, but at a cost of higher mortality.

Alyokhin, A., A. Buzza, and J. Beaulieu. 2019. Effects of food substrates and moxidectin on development of black soldier fly, Hermetia illucens. Journal of Applied Entomology 143: 137-143.
Black soldier fly is a common and widely distributed saprophagous species that has an excellent potential for being used for biological conversion of organic wastes on an industrial scale. The main goal of the reported study was expanding the list of wastes suitable for utilization by this species. We compared larval growth on cull potatoes, horse manure and cafeteria food waste in 100-L bins in a greenhouse. We also conducted laboratory experiments to investigate whether black soldier fly larvae are affected by the presence of moxidectin, a common endectocide used to treat an array of domestic animals and readily excreted in faeces, in their food substrates. Feeding on potatoes resulted in slower growth, and the final size of potato-fed larvae was smaller compared to the larvae fed on cafeteria waste. Nevertheless, potatoes supported substantial biomass accumulation, and could be a valuable option for rearing fly larvae for commercial feed production. Larvae feeding on horse manure gained very little weight and eventually failed to pupate. Moxidectin had a strong negative effect on larval survivorship; however, ca. 30% of larvae reared in the substrate containing a realistic field concentration of moxidectin still survived to adulthood. Our findings confirm that using black soldier fly larvae is a promising technology for recycling organic wastes, including those of plant origin.

Galimberti, A. and A. Alyokhin. 2018. Lethal and sublethal effects of mineral oil on potato pests. Journal of Economic Entomology 111: 1261-1267.
Mineral oil is a product used to reduce Potato Virus Y transmission in potato fields. However, there is little information available about other effects that oil may have on insect pests of potato. To better understand how mineral oil affects potato pests, we performed a series of experiments testing the effects of oil on mortality, behavior, and development of potato aphids, Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae), green peach aphids, Myzus persicae (Sulzer) (Hemiptera: Aphididae), and Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). All three species showed negative behavioral responses to oil-treated potato foliage. Oil treatment also increased aphid mortality. Colorado potato beetle mortality was not affected, but developing on oil-treated potato plants resulted in prolonged development and smaller adults. Additionally, oil acted synergistically with the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae); Colorado potato beetle larvae were killed more rapidly when sprayed with both products compared with when sprayed with B. bassiana alone. Based on these results, mineral oil has the potential for expanded use in potato IPM programs.

Alyokhin, A. and Y. H. Chen. 2017. Adaptation to toxic hosts as a factor in the evolution of insecticide resistance. Current Opinion in Insect Science 21: 33-38.
Insecticide resistance is a serious economic problem that jeopardizes sustainability of chemical control of herbivorous insects and related arthropods. It can be viewed as a specific case of adaptation to toxic chemicals, which has been driven in large part, but not exclusively, by the necessity for insect pests to tolerate defensive compounds produced by their host plants. Synthetic insecticides may simply change expression of specific sets of detoxification genes that have evolved due to ancestral associations with host plants. Feeding on host plants with more abundant or novel secondary metabolites has even been shown to prime insect herbivores to tolerate pesticides. Clear understanding of basic evolutionary processes is important for achieving lasting success in managing herbivorous arthropods.

Alpuerto, J. B., A. Mukherjee, A. Kitazumi, A. Alyokhin, D. De Koeyer, and B. G. de los Reyes. 2017. Impaired expression of the beta and delta isoforms of vacuolar processing enzymes compromise the basal defenses of Arabidopsis thaliana against the phloem-feeding insect Myzus persicae. Acta Physiologiae Plantarum 39: 233. https://doi.org/10.1007/s11738-017-2529-z.
While the functions of vacuolar processing enzymes (VPE) in plant responses to pathogens are now better established, their possible roles against insect herbivores need validation. Inspired by an observation that ßVPE and dVPE represent the most highly upregulated transcripts in leaves of Solanum bulbocastanum and its backcross progenies that were highly resistant to the phloem-feeding green peach aphids (Myzus persicae), we used a reverse genetic approach in Arabidopsis to investigate whether T-DNA insertion mutants for specific ßVPE and dVPE loci would exhibit compromised defenses at the whole-plant, physiological, and molecular levels. We hypothesized that impaired expression of VPE genes would lead to hyper-susceptibility if VPE-mediated processes were essential for basal defenses, given that Arabidopsis is naturally susceptible. Compared to the wild-type, ßvpe and dvpe mutants exhibited an early onset of leaf curling and necrosis, rapid aphid population build-up, and significant physiological tissue injuries as a result of herbivory. This indicates that basal defenses were compromised by the loss-of-functions of either VPE-encoding gene. VPE co-expression networks were comprised of genes involved in sucrose metabolism and transport (AtSUC5, AtSUS3, and invertases), efflux and oxidative detoxification proteins, and modulators of gene-for-gene-type disease response linked to sucrose metabolism (AtSWEET13 and AtSWEET15). These results suggest that VPEs play a role in basal defenses by mediating mechanisms of detoxification and metabolite availability in host tissues to counteract the rapid depletion caused by the phloem sucker. These processes might be important as first line of defense to delay the progression of perturbations caused by herbivory.

Lamb, R.J., P.A. MacKay, and A. Alyokhin. 2017. Estimating population variability of aphids (Hemiptera: Aphididae): how many years are required? Canadian Entomologist 149: 48-55.
Variability is an important characteristic of population dynamics, but the length of the time series required to estimate population variability is poorly understood. To this end, population variability of Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aphis nasturtii (Kaltenbach) (Hemiptera: Aphididae) was investigated. Population variability (measured as PV, a proportion between 0 and 1) was estimated for time series of 3–62 years, giving replicate estimates for time series of 3–20 years that were normally distributed. Mean values for PV were more uniform for a time series of 12 years or longer than for shorter ones. The standard deviation of PV declined to a minimum at 12–15 years, as the length of the time series increased. Discrimination of estimates of PV was reliable for 15-year time series and longer, but not necessarily for shorter ones. Although M. euphorbiae had a relatively low PV, the coefficient of variation of that PV (12.5), was higher than for the other two species (3.5, 4.5). For robust estimates of PV, a time series of 15 years is recommended, because it minimises the standard deviation of PV, and discriminates values of PV that differ by 0.06 on a 0–1 scale.

Booth, E., A. Alyokhin, and S. Pinatti. 2017. Adult cannibalism in an oligophagous herbivore, the Colorado potato beetle. Insect Science 24: 295-302.
Cannibalism, or intraspecific predation, can play a major role in changing individual fitness and population processes. In insects, cannibalism frequently occurs across life stages, with cannibals consuming a smaller or more vulnerable stage. Predation of adult insects on one another is considered to be uncommon. We investigated adult cannibalism in the Colorado potato beetle, Leptinotarsa decemlineata (Say), which is an oligophagous herbivore specializing on plants in family Solanaceae, and an important agricultural pest. Under laboratory conditions, starvation and crowding encouraged teneral adults to feed upon each other, which reduced their weight loss during the period of starvation. However, pupae were attacked and consumed before adults. Injured beetles had a higher probability of being cannibalized than intact beetles. Males were more frequently attacked than females, but that appeared to be a function of their smaller size rather than other gender-specific traits. Cannibalizing eggs at a larval stage did not affect beetle propensity to cannibalize adults at an adult stage. When given a choice between conspecific adults and mealworms, the beetles preferred to eat conspecifics. Cannibalistic behavior, including adult cannibalism, could be important for population persistence in this species.

Booth, E. and A. Alyokhin. 2016. Colorado potato beetle response to potato plants infected with Potato Virus Y and Potato Leafroll Virus. American Journal of Potato Research 93: 213-223.
Agricultural systems are often simultaneously impacted by multiple stressors. In our study, we investigated the effects of two commonly occurring viruses of potato, Potato virus Y (PVY) and Potato leafroll virus (PLRV) on host plant selection and utilization across various spatial scales by the Colorado potato beetle. Adult beetles selected PLRV-infected foliage in the cage choice trails, and larvae that fed exclusively on PLRV-infected foliage developed into larger adults. PVY-infected foliage was avoided in the cage trials and had no effect on the weight of developing adults. In field trials, preference and utilization of potato plants was more dependent on plant size than on virus infection. These results demonstrate that while virus-infected plants can cause physiological changes that influence beetle preference, beetle abundance and/or distribution is driven by a more complex array of factors at the field level. Additionally, this study demonstrates the importance of investigating the applicability of laboratory findings at the field level.

Chen, J., A. Kitazumi, J. Alpuerto, A. Alyokhin, and B. de los Reyes. 2016. Heat-induced mortality and expression of heat shock proteins in Colorado potato beetles treated with imidacloprid. Insect Science 23: 548-554.
The Colorado potato beetle is an important pest of solanaceous plants in the Northern Hemisphere. Better understanding of its physiological responses to temperature stress and their interactions with still-prevalent chemical control has important implications for the management of this insect. We measured mortality and expression of the Hsp70 heat shock proteins in the Colorado potato beetle larvae exposed to sublethal concentration of the commonly used insecticide imidacloprid, and to supraoptimal temperatures. Both turned out to be significant stress factors, although induction of Hsp70 by imidacloprid observed in the present study was low compared to its induction by the heat. The two factors also interacted with each other. At an extreme temperature of 43 °C, exposure to a sublethal dose of imidacloprid resulted in a significant rise in larval mortality, which was not observed at an optimal temperature of 25 °C. Heat-stressed larvae also failed to respond to imidacloprid by producing more Hsp70. These findings suggest that when field rates of insecticides become insufficient for killing the exposed beetles under optimal temperature conditions due to the evolution of resistance in beetle populations, they may still reduce the probability of resistant beetles surviving the heat shock created by using propane flamers as a rescue treatment.

Alyokhin, A. and L. Miller. 2015. Propensity for flying and walking by the Colorado potato beetles treated with imidacloprid. American Journal of Potato Research 92: 138-142.
The Colorado potato beetle, Leptinotarsa decemlineata (Say) is a very serious pest of potatoes which is highly mobile and capable of rapid evolution of resistance to chemical control. Insect movement, resulting in gene flow between resistant and susceptible populations, is considered to be an important factor affecting the development and spread of insecticide resistance. We investigated the movement of adult Colorado potato beetles by flight and by walking following the treatment with a sublethal dose of imidacloprid in the laboratory. Imidacloprid had a pronounced negative effect on beetle mobility. The proportion of beetles flying and walking, as well as the number and duration of performed flights, were significantly decreased for the treated beetles. Since local selection followed by long-distance dispersal have been reported to lead to serious area-wide problems with the insecticide-resistant Colorado potato beetle, longterm suppression of flight activity recorded in our study suggests that imidacloprid applications may reduce outflow of resistant alleles.

Alyokhin, A., D. Mota-Sanchez, M. Baker, W. E. Snyder, S. Menasha, M. Whalon, G. Dively, and W. F. Moarsi. 2015. Red Queen on a potato field: IPM vs. chemical dependency in Colorado potato beetle control. Pest Management Science 71: 343-356.
Originally designed to reconcile insecticide applications with biological control, the concept of integrated pest management (IPM) developed into the systems-based judicious and coordinated use of multiple control techniques aimed at reducing pest damage to economically tolerable levels. Chemical control, with scheduled treatments, was the starting point for most management systems in the 1950s. Although chemical control is philosophically compatible with IPM practices as a whole, reduction in pesticide use has been historically one of the main goals of IPM practitioners. In the absence of IPM, excessive reliance on pesticides has led to repeated control failures due to the evolution of resistance by pest populations. This creates the need for constant replacement of failed chemicals with new compounds, known as the ?insecticide treadmill?. In evolutionary biology, a similar phenomenon is known as the Red Queen principle ? continuing change is needed for a population topersevere because its competitors undergo constant evolutionary adaptation. The Colorado potato beetle, Leptinotarsa decemlineata (Say), is an insect defoliator of potatoes that is notorious for its ability to develop insecticide resistance. In the present article, a review is given of four case studies from across the United States to demonstrate the importance of using IPM for sustainable management of a highly adaptable insect pest. Excessive reliance on often indiscriminate insecticide applications and inadequate use of alternative controlmethods, such as crop rotation, appear to expedite evolution of insecticide resistance in its populations. Resistance to IPM would involve synchronized adaptations to multiple unfavorable factors, requiring statistically unlikely genetic changes. Therefore, integrating different techniques is likely to reduce the need for constant replacement of failed chemicals with new ones.

Patterson, M. and A. Alyokhin. 2014. Survival and development of Colorado potato beetles on potatoes treated with phosphite. Crop Protection 61: 38-42.
Phosphite is a general term used to describe the salts of phosphorous acid H3PO3. It is effective in suppressing a number of plant diseases caused by oomycetes and has been shown to reduce populations of several insect species. We investigated the effects of phosphite on the Colorado potato beetles in the field and laboratory. Beetle numbers and defoliation on phosphite-treated plots were lower compared to the control plots during one out of two years of the study. No phosphite effects were detected in the field during the second year of the study. However, larval mortality was significantly higher the second year in the laboratory when larvae were fed on potato foliage excised from the potato plants treated with phosphite in the field. Laboratory tests with excised leaves dipped in a solution of phosphite revealed lower beetle survivorship and prolonged development on the treated foliage. Because of its dual properties as a fungicide and an insecticide, as well as its low toxicity to vertebrates, phosphite is a potentially good fit for integrated pest management programs.

Chen, J., A. Alyokhin, D. Mota-Sanchez, M. Baker and M. Whalon. 2014. Variation in fitness among geographically isolated Colorado potato beetle (Coleoptera: Chrysomelidae) populations. Annals of the Entomological Society of America 107: 128-135.
Colorado potato beetle, Leptinotarsa decemlineata (Say) is a major pest of potatoes in North America, Europe, and parts of Asia. It adapts quickly to adverse environments, thereby limiting the longevity of control strategies. Better understanding of variability among geographically isolated populations of this insect might create an opportunity to customize control techniques for local conditions. We investigated insecticide resistance, heat tolerance, and growth potential in six beetle populations collected from different locations in the United States. Significant differences were detected in insecticide resistance, egg mass size, and egg hatchability among the tested populations. Large egg mass size appeared to be offset by lower egg hatchability. We also observed a female-biased sex ratio at least in one of the strains. Population growth rates were different among the strains, but this parameter was not correlated to insecticide resistance. This suggests that using allopatric populations in comparative studies of insecticide resistance might result in confusing effects of geographic isolation with the effects of selection towards resistance.

Baker, M., K. Hossain, K. Zabierek, K. Collie, A. Alyokhin, D. Mota-Sanchez, and M. Whalon. 2014. Geographic variation in cannibalism in Colorado potato beetle populations. Environmental Entomology 43: 102-109.
Cannibalism can have a large effect on population growth and survival in stressful environments, possibly including those created by insecticide use. In this study, we collected Colorado potato beetles from three isolated areas in the northeastern United States known for high levels of resistance to neonicotinoids. We measured resistance to imidacloprid in each of those populations, a laboratory susceptible population, and in hybrids between the three field populations and the laboratory susceptible population. We fed neonates eggs from resistant dams fed either imidaclopridtreated or untreated foliage to determine whether cannibals are exposed to toxins sequestered in eggs. We measured egg cannibalism by hatchlings within the clutch in each population and hybrids, and examined how fecundity and several variables associated with egg development varied among populations and with cannibalism, to see which traits might enhance or reduce cannibalism. Cannibalism varied significantly among populations, accounting for most of the variation in hatching success. Variability in egg development time and hatch rate in the absence of cannibalism in some populations affected rates of cannibalism. Resistance varied significantly among the ?eld populations but was not related to cannibalism. Neonates fed eggs from dams on treated foliage showed signs of intoxication or death. Cannibalism appears to be part of a varying life history strategy in this species, with some populations laying larger and more cannibalistic clutches and the New York population laying smaller clutches with higher hatching success owing to reduced cannibalism.

Bernard, E., R. P. Larkin, S. Tavantzis, M. S. Erich, A. Alyokhin, and S. D. Gross. 2014. Rapeseed rotation, compost and biocontrol amendments reduce soilborne diseases and increase tuber yield in organic and conventional potato production systems. Plant Soil 374: 611?627.
Aims Integrating multiple soil and disease management practices may improve crop productivity and disease control, but potential interactions and limitations need to be determined.
Methods Three different potential disease-suppressive management practices, including a Brassica napus (rapeseed) green manure rotation crop, conifer-based compost amendment, and three biological control organisms (Trichoderma virens, Bacillus subtilis, and Rhizoctonia solani hypovirulent isolate Rhs1A1) were evaluated alone and in combination at sites with both organic and conventional management histories for their effects on soilborne diseases and tuber yield.
Results Rapeseed rotation reduced all observed soilborne diseases (stem canker, black scurf, common scab, and silver scurf) by 10 to 52 % in at least one year at both sites. Compost amendment had variable effects on tuber diseases, but consistently increased yield (by 9 to 15 %) at both sites. Biocontrol effects on disease varied, though Rhs1A1 decreased black scurf at the conventional site and T. virens reduced multiple diseases at the organic site in at least one year. Combining rapeseed rotation with compost amendment both reduced disease and increased yield, whereas biocontrol additions produced only marginal additive effects.
Conclusions Use of these treatments alone, and in combination, can be effective at reducing disease and increasing yield under both conventional and organic production practices.

Lamb, R. J., P. A. MacKay, and A. Alyokhin. 2013. Seasonal dynamics of three coexisting aphid species: implications for estimating population variability. Canadian Entomologist 145: 283?291.
Seasonal patterns of abundance and population variability were determined for Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aphis nasturtii (Kaltenbach) (Hemiptera: Aphididae) in potato plots from weekly samples for 28 years. All species showed a single annual peak, but arrived and reached peak abundance at different times. Population variability (PV, a proportion between 0 and 1) for the week of peak abundance was close to that of other sample weeks and mean seasonal abundance. Based on mid-season abundance, PV of 0.76 for M. persicae differed significantly from 0.80 for A. nasturtii, as well as from 0.59 for M. euphorbiae. A weekly time scale for abundance, initiated at an early stage of plant growth, produced slightly different estimates of PV early and late in the season than a scale centred on peak abundance for each species. PV at the time of invasion differed from estimates for the rest of the summer. The annual abundance used to estimate PV was best determined in the context of aphid life history. Nevertheless, PV provided a robust and precise metric for comparing population variability among the three species, regardless of their seasonal patterns of abundance.

Leppanen, C., A. Alyokhin, and S. Gross. 2012. Competition for aphid prey between different lady beetle species in a laboratory arena. Psyche: A Journal of Entomology 2012: Article ID 890327, 9 pp.
Direct competition for aphid prey (Hemiptera: Aphididae) was evaluated between and among several lady beetle species (Coleoptera: Coccinellidae). The behavior of three native (Coccinella trifasciata, Coleomegilla maculata, and Hippodamia convergens) and four nonnative (Coccinella septempunctata, Harmonia axyridis, Hippodamia variegata, and Propylea quatuordecimpunctata) lady beetles was observed in laboratory arenas. The beetles were kept alone, paired with conspecifics or paired with heterospecifics, and presented with potato aphids (Macrosiphum euphorbiae). Harmonia axyridis was the most successful aphid predator in our study, being able to find aphids more quickly and consume more of them compared to most other lady beetle species. It was also by far the most aggressive of the tested species. Coccinella septempunctata, C. trifasciata, and C. maculata generally followed H. axyridis in aphid consumption. Prey discovery, consumption, and aggressive behaviors were dependent on which species were present in the arena. Except for the generally superior H. axyridis, there was no obvious dominance hierarchy among the other tested species and no dichotomy between the native and non-native species. Asymmetric interactions between lady beetle species may affect their abilities to coexist in the same habitat. [Full Text]

Bernard, E., R. P. Larkin, S. Tavantzis, M. S. Erich, A. Alyokhin, G. Sewell, A. Lannan, and S. D. Gross. 2012. Compost, rapeseed rotation, and biocontrol agents significantly impact soil microbial communities in organic and conventional potato production systems. Applied Soil Ecology 52: 29? 41.
Cultural practices such as organic amendments, rotations, and use of biological control organisms are regularly investigated for their effects on controlling plant diseases but their effects on soil microbial populations are often unexplored. In this study, three different sustainable disease management practices, use of compost amendment, biocontrol organisms, and a potentially disease-suppressive rotation, were established in potato field trials at two sites under different management regimes and histories, and evaluated over three potato cropping seasons for their effects on soil microbial communities. Specific management factors assessed included the presence or absence of a conifer-based compost amendment, addition of one of three different biocontrol organisms (Trichoderma virens, Bacillus subtilis, and Rhizoctonia solani isolate Rhs1A1), and a Brassica napus (rapeseed) green manure rotation crop preceding potato, and treatments were assessed in all factorial combinations. The two farm sites represented organic and conventional potato production practices in Aroostook County, Maine. Compost amendment and rapeseed rotation had the greatest impacts on soil microbial communities, with both treatments increasing total populations of culturable bacteria at both sites over the course of the study, as well as causing detectable shifts in soil microbial community characteristics as determined by sole carbon-source substrate utilization and fatty acid methyl ester (FAME) profiles. Compost amendment generally led to increased utilization of complex substrates and increased levels of Gram-positive bacteria and fungi, and compost effects were more pronounced at the conventional site. Rapeseed rotation often resulted in somewhat different effects at the two different sites. Consistent overall effects were observed with the biocontrol amendments Rhs1A1 and T. virens, including increased microbial activity and bacterial populations. Combined effects of multiple treatments were greater than those of individual treatments and were generally additive. These results indicate that each treatment factor had significant and specific effects on soil microbial communities, and that combined effects tended to be complementary, suggesting the potential of combining multiple compatible management practices and their associated changes in soil microbial communities.

Alyokhin, A. 2011. Scant evidence supports EPA's pyramided Bt corn refuge size of 5%. Nature Biotechnology 29: 577?578.
No abstract available

Alyokhin, A., F. A. Drummond, G. Sewell, and R. H. Storch. 2011. Differential effects of weather and natural enemies on coexisting aphid populations. Environmental Entomology 40: 570-580.
Study of mechanisms responsible for regulating populations of living organisms is essential for a better comprehension of the structure of biological communities and evolutionary forces in nature. Aphids (Hemiptera: Sternorrhyncha) comprise a large and economically important group of phytophagous insects distributed worldwide. Previous studies determined that densitydependent mechanisms play an important role in regulating their populations. However, only a few of those studies identi?ed speci?c factors responsible for the observed regulation. Time series data used in this study originated from the untreated control plots that were a part of potato (Solanum tuberosum L.) insecticide trials in northern Maine from 1971 to 2004. The data set contained information on population densities of three potato-colonizing aphid species (buckthorn aphid, Aphis nasturtii; potato aphid, Macrosiphum euphorbiae; and green peach aphid, Myzus persicae) and their natural enemies. We used path analysis to explore effects of weather and natural enemies on the intrinsic growth rates of aphid populations. Weather factors considered in our analyses contributed to the regulation of aphid populations, either directly or through natural enemies. However, direct weather effects were in most cases detectable only at P.0.10. Potato aphids were negatively affected by both fungal disease and predators, although buckthorn aphids were negatively affected by predators only. Parasitoids did not have a noticeable effect on the growth of any of the three aphid species. Growth of green peach aphid populations was negatively in?uenced by interspeci?c interactions with the other two aphid species. Differential population regulation mechanisms detected in the current study might at least partially explain coexistence of three ecologically similar aphid species sharing the same host plant.

Lamb, R. J., P. A. MacKay, and A. Alyokhin. 2011. Population variability and persistence of three aphid pests of potatoes over 60 years. Canadian Entomologist 143: 91?101.
Abundance, persistence, and variability of populations of Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aphis nasturtii Kaltenbach (Hemiptera: Aphididae) in potato plots for intervals of 58 years (n=1), 29 years (n=2), 19?20 years (n=3), and 9?10 years (n=6) were compared. The abundance of M. euphorbiae showed no trend among decades and varied 2.4-fold, whereas that of M. persicae and A. nasturtii declined and showed 54-fold and 3700-fold variation, respectively. All three aphid species persisted through the first five decades and M. euphorbiae also persisted through the sixth (last) decade, but M. persicae and A. nasturtii failed to persist for 1 and 3 years of the last decade, respectively. Population variability (a proportion between 0 and 1) measured over a 58-year interval was high: 0.585 for M. euphorbiae, 0.771 for M. persicae, and 0.830 for A. nasturtii. During the first three but not the last three decades, population variability increased with sampling interval, owing to dramatic declines in abundance for M. persicae and A. nasturtii and one stable decade for M. euphorbiae, but no evidence of a more-time 2 more-variation effect was detected. Persistence was not related to population variability, but declined with abundance. Populations did not reach equilibrium, because of declining abundance for M. persicae and A. nasturtii and changes in population variability from decade to decade for M. euphorbiae. Populations of M. persicae and A. nasturtii from this crop monoculture were less stable than previously studied natural populations of a native aphid species. In contrast, the population of M. euphorbiae, a native species, had variability in a potato crop similar to that of the previously studied native species. The high population variability of M. persicae and A. nasturtii may be associated with their status as introduced species. The dynamic and species-specific characteristics of population variability require that interspecific comparisons be considered cautiously.

Alyokhin, A. and R. Choban. 2010. Maturity-dependent mortality of Colorado potato beetle eggs treated with novaluron. American Journal of Potato Research 87: 557?560.
Novaluron is a chitin synthesis inhibitor (a benzoylphenyl urea) that kills larval stages and causes reversible cessation of laying viable eggs in adults of the Colorado potato beetle, Leptinotarsa decemlineata (Say). Previous studies also suggest that it has ovicidal properties, but not on all tested egg masses. We investigated if egg maturity at the time of exposure affects its susceptibility to novaluron. Novaluron application significantly reduced the hatch of eggs that were 0?24 h old at the moment of treatment, but had no effect on the eggs that were 96?120 h old. Novaluron also interfered with the development of the hatched larvae regardless of the egg age at the time of treatment, probably due to chorion feeding by neonates. Ovicidal properties of novaluron may contribute to Colorado potato beetle control, but their effect will be limited to newly laid eggs. If that window of susceptibility is missed, hatching larvae will be exposed to a fairly old novaluron residue that might be weathered down to sublethal levels. This supports the current recommendations to apply novaluron as a larvicide.

Finlayson, C., A. Alyokhin, S. Gross, and E. Porter. 2010. Differential consumption of four aphid species by four lady beetle species. 10pp. Journal of Insect Science 10:31, available online: insectscience.org/10.31.
The acceptability of four different aphid species, Macrosiphum albifrons (Essig), Macrosiphum euphorbiae (Thomas), Macrosiphum pseudorosae Patch, and Myzus persicae (Sulzer) (Hemiptera: Aphididae), as prey for four lady beetle species, one native species Coccinella trifasciata L, and three non-native species, Coccinella septempunctata L, Harmonia axyridis Pallas, Propylea quatuordecimpunctata L (Coleoptera: Coccinellidae) were tested in the laboratory. The relative field abundance of adults of the same lady beetle species on host vegetation, Lupinus polyphyllus Lindl. (Fabales: Fabaceae), Solanum tuberosum L (Solanales: Solanaceae), and Rosa multiflora Thunberg(Rosales: Rosaceae), both with and without aphids present was also observed. In the laboratory, H. axyridis generally consumed the most aphids, while P. quatuordecimpunctata consumed the fewest. The exception was P. quatuordecimpunctata, which consumed a greater number of M. albifrons nymphs, and C. trifasciata, which consumed a greater number of M. albifrons nymphs and adults, compared with the other two beetle species. Lady beetles consumed fewer M. albifrons compared with the other three aphid species, likely because of deterrent compounds sequestered by this species from its host plant. In the field, P. quatuordecimpunctata was the most abundant species found on L. polyphyllus and S. tuberosum.

Alyokhin, A., J. Makatiani, and K. Takasu. 2010. Insecticide odour interference with food-searching behaviour of Microplitis croceipes (Hymenoptera: Braconidae) in a laboratory arena. Biocontrol Science and Technology 20: 317-329.
Response to odours plays an important role in resource location by natural enemies, particularly by parasitoid wasps. While a considerable research effort has been dedicated to studying the effects of insecticide intoxication on natural enemy search behaviour, it is yet unknown if the odours themselves interfere with distant chemoreception. We investigated this issue using the food-searching behaviour of Microplitis croceipes (Cresson)(Hymenoptera: Braconidae) in laboratory arenas as a model system. Odours of imidacloprid (Genesis?), spinosad (Entrust?), esfenvalerate (Asana?), methamidophos (Monitor?), and vanilla were tested for their ability to interfere with wasp response to the odour of honey. The wasps did not contact the chemicals. Honey odour was generally effective in triggering food-searching behaviour in both honey-fed (and thus conditioned to associate honey odour with food) and unfed, na?ve wasps. Mixing honey with imidacloprid and spinosad did not affect wasp responses. The remaining compounds (esfenvalerate, methamidophos, and vanilla) significantly reduced the proportion of positively responding fed wasps, but only methamidophos had such an effect on the unfed wasps. Negative methamidophos effects became completely reversed when wasps were forced to feed on honey in the presence of methamidophos odour. Our results suggest that odours and provision of food may potentially be used to keep beneficial natural enemies away from insecticide-treated areas.

Alyokhin, A., R. Guillemette, and R. Choban. 2009. Stimulatory and suppressive effects of novaluron on the Colorado potato beetle reproduction. Journal of Economic Entomology 102: 2078-2083.
The Colorado potato beetle, Leptinotarsa decemlineata (Say), is one of the most damaging insect pests of potato. Novaluron is a relatively new benzoylphenyl urea insect growth regulator with good activity against this pest. Earlier studies revealed that feeding on potato foliage treated with novaluron induces reversible egg hatch inhibition in adult Colorado potato beetles. We investigated if novaluron effects depend on physiological state of the beetles at the time of exposure. The following four treatments were created: young beetles unmated at the beginning of the experiment and feeding on potato foliage treated with novaluron, young beetles unmated at the beginning of the experiment and feeding on untreated foliage, older beetles mated at the beginning of the experiment and feeding on foliage treated with novaluron, and older beetles mated at the beginning of the experiment and feeding on untreated foliage. The beetles were exposed to the respective treatments for five days. After that, both young and older beetles feeding on novaluron-treated leaves were switched onto untreated leaves and monitored for another five days to test their ability to recover. Young beetles unmated at the beginning of the experiment produced more eggs after feeding on the treated foliage, possibly indicating the presence of a pesticide-induced homeostatic modulation. No such effect was observed in the older beetles. Regardless of beetle physiologigal state at the beginning of the experiment, eggs produced on treated foliage did not hatch. The beetles eventually resumed laying viable eggs after being switched onto untreated foliage, with the recovery being delayed by ca. 24 hours in young beetles compared to older beetles. Our results corroborate that novaluron reduces fertility of treated adults. [Full Text]

Finlayson, C. J., A. V. Alyokhin, and E. W. Porter. 2009. Interactions of native and non-native lady beetle species (Coleoptera: Coccinellidae) with aphid-tending ants in laboratory arenas. Environmental Entomology 38: 846-855.
Interactions between lady beetles and the European fire ant (Myrmica rubra L.) tending potato aphids [Macrosiphum euphorbiae (Thomas)] were compared in the laboratory. Lady beetle species native to North America (Coccinella trifasciata perplexa Mulsant, Coleomegilla maculata lengi Timberlake, Hippodamia convergens Guerin-Meneville) and non-native species of Palearctic origin [Coccinella septempunctata L., Harmonia axyridis (Pallas), Hippodamia variegata (Goeze), Propylea quatuordecimpunctata L.)] were evaluated. Harmonia axyridis consumed a significantly greater number of aphids compared with all other species but C. septempunctata. Ant stings affected H. variegata and C. septempunctata to a greater extent than other species. Ants showed a significantly greater amount of aggression toward H. convergens and H. variegata compared with P. quatuordecimpunctata. P. quatuordecimpunctata, C. trifasciata, and H. axyridis reacted significantly less to ants compared with H. variegata, H. convergens, C. maculata, and C. septempunctata. Differences in interactions with natural enemies may explain, in part, the successful establishment of some non-native coccinellids in new habitats. [Full Text]

Alyokhin, A. 2009. Colorado potato beetle management on potatoes: current challenges and future prospects. In: Tennant P, Benkeblia N (Eds) Potato II. Fruit, Vegetable and Cereal Science and Biotechnology 3 (Special Issue 1): 10-19. (Invited review article).
The Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) is the most important insect defoliator of potatoes that can completely destroy potato crops. Its current range covers about 16 million km² in North America, Europe, and Asia and continues to expand. A complex and diverse life history, combined with an impressive ability to develop insecticide resistance, make the Colorado potato beetle a challenging pest to manage. Beetle populations on commercial farms are usually suppressed by insecticides, which are likely to remain the predominant approach for the foreseeable future. In addition, the beetles can be controlled through the use of relatively common cultural practices, with crop rotation being the most effective and easily implemented approach. In spite of a long history of breeding efforts, no commercial cultivars resistant to the Colorado potato beetles are currently available on the market. Natural enemies are usually incapable of reducing beetle densities below the economically damaging levels and have to be used in combination with other control techniques. Unfortunately, there will never be a ?silver bullet? solution to preventing the damage caused by this insect. The only sustainable way to protect potato crops is to integrate multiple control techniques into a scientifically sound management approach. This is not an easy task, but the only alternatives are recurrent crop losses in combination with environmental degradation. [Full Text]

Finlayson, C. J., K. M. Landry, and A. V. Alyokhin. 2008. Abundance of native and non-native lady beetles (Coleoptera: Coccinellidae) in different habitats in Maine. Annals of the Entomological Society of America 101: 1078-1087.
Several studies suggest the possibility that non-native lady beetles may have replaced native lady beetles in some agricultural habitats. There is relatively little information, however, about lady beetle species composition outside of agricultural habitats. Evans (2004) suggested that native species have retreated to nonagricultural habitats in response to the arrival of non-native lady beetles (habitat compression hypothesis). To test this hypothesis, a survey of lady beetles was conducted in 2004 and 2005 in different habitats in Maine. From May to October, lady beetles were sampled in a variety of agricultural and nonagricultural habitats. In total, 3,487 and 2,903 lady beetles were collected in 2004 and 2005, respectively. Non-native lady beetles were found in a variety of habitats, including the habitats that would have likely served as a refuge for native species if the habitat compression hypothesis applied to the surveyed areas. Native species were found in a higher proportion in agricultural habitats compared with nonagricultural habitats and in very low numbers in all of the habitats surveyed. Hippodamia tredecimpunctata tibialis (Say) and Coccinella transversoguttata Brown, the two native species that were once dominant here, made up only 1.09 and 0.07% of the total lady beetles collected, respectively. In this survey,we failed to detect evidence that native lady beetles have retreated to nonagricultural habitats in response to the arrival of non-native lady beetles. [Full Text]

Alyokhin, A., M. Baker, D. Mota-Sanchez, G. Dively, and E. Grafius. 2008. Colorado potato beetle resistance to insecticides. American Journal of Potato Research 85: 395?413. (Invited review article).
The Colorado potato beetle, Leptinotarsa decemlineata (Say), is widely regarded as the most important insect defoliator of potatoes. Its current range covers about 16 million km² in North America, Europe, and Asia and continues to expand. This insect has a complicated and diverse life history, which is well-suited to agricultural environments, and makes it a complex and challenging pest to control. Dispersal, closely connected with diapause, feeding, and reproduction, allow the Colorado potato beetle to employ "bet-hedging" reproductive strategies, distributing its offspring in both space (within and between fields) and time (within and between years).
The Colorado potato beetle played a large role in creating the modern pesticide industry, with hundreds of chemicals tested against it. High selection pressure, together with natural propensity to adapt to toxic substances, eventually resulted in a large number of insecticide-resistant Colorado potato beetle populations. Since the middle of the last century, the beetle has developed resistance to 52 different compounds belonging to all major insecticide classes. Resistance levels vary greatly among different populations and between beetle life stages, but in some cases can be very high (up to 2,000-fold).
Known mechanisms of Colorado potato beetle resistance to insecticides include enhanced metabolism involving esterases, carboxylesterases and monooxygenases, and target site insensitivity, as well as reduced insecticide penetration and increased excretion. There is also some evidence of behavioral resistance. Resistance mechanisms are sometimes highly diverse even within a relatively narrow geographical area. Resistance is usually inherited as an incompletely dominant or incompletely recessive trait, with one or several genes involved in its determination. Because of pleiotropic effects of resistant alleles, insecticide-resistant beetles often have reduced relative fitness in the absence of insecticides.
Rotating different classes of insecticides and reducing insecticidal pressure on pest populations by provision of temporal and spatial refuges from exposure to toxins have been proposed to delay evolution of resistance. However, insecticide resistance in this insect will likely remain a major challenge to the pest control practitioners. Still limited understanding of beetle biology, its flexible life history, and grower reluctance to adopt some of the resistance management techniques create impediments to successful resistance management. Overcoming these obstacles is not an easy task, but it will be crucial for sustainable potato production. [Full Text]

Alyokhin, A., G. Sewell, and R. Choban. 2008. Reduced viability of Colorado potato beetle, Leptinotarsa decemlineata, eggs exposed to novaluron. Pest Management Science 64: 94-99.
BACKGROUND: Novaluron is a benzoylphenyl urea chitin synthesis inhibitor that combines good activity against larval stages of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), with low mammalian toxicity. Previous studies suggest that it has deleterious sublethal effects on adults.
RESULTS: Continuous exposure ofadult Colorado potato beetles to novaluron-treated foliage as both ovipositional and feeding substrate did not affect their survivorship or the number ofeggs produced, but viable larvae hatched only from the eggs that were laid on the first day ofthe experiment. Viability was restored after adult beetles spent 48-96 hours on untreated leaves. In a separate experiment, direct exposure to novaluron ofeggs laid by unexposed beetles also reduced the number oflarvae hatching.
CONCLUSIONS: Results confirm a negative effect of novaluron on the number of progeny produced by the Colorado potato beetle. Direct toxicity did not explain all of the reduction in egg hatch observed, suggesting that novaluron probably acted on reproductive adults as well as on eggs after they were deposited.

Baker, M. B., A. Alyokhin, A. H. Porter, D. N. Ferro, S. R. Dastur , and N. Galal. 2007. Persistence and inheritance of costs of resistance to imidacloprid in Colorado potato beetle. Journal of Economic Entomology 100: 1871-1879.
Reduced fitness among resistant versus susceptible individuals slows resistance evolution and makes it easier to manage. A loss of resistance costs could indicate novel adaptations or mutations contributing to resistance. We measured costs of resistance to imidacloprid in a Massachusetts resistant population compared with a Massachusetts susceptible population in 1999 in terms of fecundity, hatching success, egg development time, and sprint speed. Resistance was additive and seemed to be polygenic with high heritability. The fecundity cost appeared overdominant in 1999, and the hatch rate cost was partly recessive in 1999, but neither was signi?cantly different from dominant or recessive. In 2004, we repeated our measures of resistance costs in Massachusetts in terms of fecundity and hatching success, and we added a new resistant population from Maine. In 2005, we compared development time of Maine resistant and the laboratory susceptible colony eggs. Significant fecundity costs of resistance were found in both population in both 1999 and 2004, and significant egg developmental time costs were found in 1999 and 2005. However, the hatching success costs of resistance were significant in 1999 and not apparent in 2004, suggesting some modification or replacement of the resistance genes in the intervening time. [Full Text]

Andreson, M.W., M. Teisl, G. Criner, S. Tisher, S. Smith, M. Hunter, S. Norton, J. Jellison, A. Alyokhin, E. Gallandt, S. Haggard, and E. Bicknell. 2007. Attitude changes of undergraduate university students in general education courses. The Journal of General Education 56: 149-168.
No abstract available.

Alyokhin, A., G. Dively, M. Patterson, C. Castaldo, D. Rogers, M. Mahoney, and J. Wollam. 2007. Resistance and cross-resistance to imidacloprid and thiamethoxam in the Colorado potato beetle. Pest Management Science 63: 32-41.
One of the major challenges in managing the Colorado potato beetle, Leptinotarsa decemlineata (Say) is its remarkable ability to develop insecticide resistance to virtually every chemical that has ever been used against it. Resistance is particularly common throughout northeastern U.S. as far north as Maine. The first instances of resistance to imidacloprid have been already reported from several locations in New York, Delaware, and southern Maine. Rotating insecticides with different modes of action may delay insecticide resistance, but successful implementation of this technique depends on a good understanding of resistance and cross-resistance patterns in populations of target pests. We measured LC50 values for imidacloprid and thiamethoxam in Colorado potato beetle populations from a variety of locations in the U.S. and Canada using diet incorporation bioassays. We also evaluated field performance of imidacloprid, thiamethoxam, and clothianidin against imidacloprid-resistant beetles on a commercial potato farm in southern Maine. Correlation between LC50 values for imidacloprid and thiamethoxam was highly significant, even when populations previously exposed to thiamethoxam were excluded from the analysis. There was no statistically detectable difference in the LC50 values between populations exposed to both chemicals and to imidacloprid alone. Applications of neonicotinoid insecticides at planting delayed build-up of imidacloprid-resistant beetle populations on field plots by 1-2 weeks, but failed to provide adequate crop protection. Consistently with bioassay results, there was also substantial cross-resistance among the three tested neonicotinoid insecticides. Results of the present study support the recommendation to avoid rotating imidacloprid with thiamethoxam as a part of resistance management plan.

Alyokhin, A., G. Dively, M. Patterson, D. Rogers, M. Mahoney, and J. Wollam. 2006. Susceptibility of imidacloprid-resistant Colorado potato beetles to non-neonicotinoid insecticides in the laboratory and field trials. American Journal of Potato Research 83: 485-494.
Repeated use of neonicotinoid insecticides has resulted in the first reported cases of Colorado potato beetle (Leptinotarsa decemlineata (Say)) resistance to imidacloprid. In the laboratory we determined susceptibility of the imidacloprid-resistant Colorado potato beetles from a population in Southern Maine to other insecticides currently registered for use on potato. This population was about 30-fold resistant to imidacloprid and could not be effectively controlled by its applications. Control mortality was significantly higher for the imidacloprid-resistant larvae than for the susceptible larvae, suggesting that fitness disadvantages may be associated with the resistance trait. Resistant larvae exhibited significantly less mortality than susceptible larvae when exposed to cyfluthrin, carbaryl, azinphosmethyl, and methamidophos. Their susceptibility to oxamyl was also somewhat reduced, although it did provide nearly 100% mortality at the highest concentration tested. Disulfoton was highly toxic to the resistant larvae. Oxamyl killed about 40% of the adults in greenhouse assays with potted potato plants, altered their feeding behavior (fewer adults up on plants), and reduced defoliation by more than 90%. Disulfoton was not lethal to adults, but significantly suppressed their feeding. In field trials with the resistant population, oxamyl and imidacloprid + spinosad provided the best beetle control. Novaluron had no detectable effect on beetle densities. There was little difference between the plots treated with imidacloprid or thiamethoxam and the untreated control. Our results suggest that insecticide rotation may be a valuable option for managing imidacloprid-resistant Colorado potato beetle populations. We also had a good consistency between the results of the Petri dish, greenhouse, and field experiments, indicating that screening under laboratory confinement may be useful when developing initial recommendations to potato growers in areas affected by resistance to neonicotinoids. [Full Text]

Narayandas, G. and A. Alyokhin. 2006. Diurnal patterns in host finding by potato aphids, Macrosiphum euphorbiae (Homoptera: Aphididae). Journal of Insect Behavior 19: 347-356.
Potato aphid, Macrosiphum euphorbiae (Homoptera: Aphididae), is an abundant potato pest and vector of potato leaf-roll virus and potato virus Y in Maine and other potato growing areas. We investigated the circadian rhythmicity of its movement towards host plant odor. Effects of daily cycle (day or night) and illumination (light or dark) on the proportion of aphids colonizing potato leaflets were determined in a Petri plate arena and in a Y-tube olfactometer. In Petri dishes, both daily cycle and light had a highly signifi- cant effect on plant colonization. Increasing temperature reduced aphid colonization of the leaflets. In the olfactometer, light had a significant effect on the proportion of aphids walking towards the host plant. Interaction between time and light was also statistically significant, with the effect of illumination being smaller during the day than during the night. Our results suggest that circadian rhythm in host-finding behavior of the potato aphid is regulated by both exogenous and endogenous mechanisms.

Narayandas, G., A. Alyokhin, R. Alford, D. Weber, and J. C. Dickens. 2006. Response of potato aphid (Homoptera: Aphididae) to synthetic potato-derived Colorado potato beetle attractant and natural potato odor. Journal of Economic Entomology 99: 1203-1208.
A recently synthesized kairomone blend, based on the volatiles produced by potato plants, has been demonstrated to be attractive to both adult and larval stages of the Colorado potato beetle, Leptinotarsa decemlineata (Say). It was subsequently formulated in a viscous inert carrier for field applications and showed potential for aggregating beetles in treated areas of the field. We investigated effects of this kairomone formulation on the potato aphid, Macrosiphum euphorbiae (Thomas). The response of both winged and wingless adults to natural potato foliage and synthetic kairomone was tested in a Y-tube olfactometer. Aphid response to untreated potato foliage, foliage treated with the kairomone blend, and foliage treated with blank inert carrier was also tested in Petri dishes. In addition, aphid densities on field plots treated with kairomone and blank inert carrier were compared to the control plots. The untreated potato foliage was found to be attractive to wingless, but not winged, potato aphids. In the olfactometer, the foliage treated with synthetic Colorado potato beetle kairomone was not attractive to either winged or wingless aphids. In Petri dishes, aphids avoided leaflets treated with both kairomone formulation and its blank carrier. There was no statistical difference between any treatments compared in the field. [Full Text]

Narayandas, G. and A. Alyokhin. 2006. Interplant movement of potato aphid (Homoptera: Aphididae) in response to environmental stimuli. Environmental Entomology 35: 733-739.
Potato aphid, Macrosiphum euphorbiae (Thomas), is a highly mobile aphid species that dominates aphid communities in Maine potato fields and may contribute to virus transmission between potato plants. We studied effects of simulated rain, wind, mechanical raking, fungicide application, reflective mulch, and predator (lady beetle, Harmonia axyridis (Pallast) on the interplant movement of wingless adult potato aphids in greenhouse experimental arenas that imitated small segments of a potato field. The number of aphids dispersing from the central plant in the arena following tested perturbation was recorded. Experiments were repeated with 3-4 week old plants with non-overlapping canopies and with 4-5 week old plants with canopies overlapping within rows. Aphids moved between potato plants even when canopies did not overlap, and without any environmental perturbations. However, more aphids moved between larger plants with overlapping canopies. Rain significantly encouraged aphid movement between plants with non-overlapping canopies. Wind, rain, and mechanical raking significantly encouraged aphid movement between plants with overlapping canopies. Regardless of canopy overlap, most aphids moved within the rows of potato plants. However, there was also considerable movement between the rows, even though the aphids had to walk over bare soil. [Full Text]

Baker, M.B., Alyokhin, A., S. R. Dastur, A. H. Porter, and D. N. Ferro. 2005. Sperm precedence in the overwintered Colorado potato beetles (Coleoptera: Chrysomelidae) and its implications for insecticide resistance management. Annals of the Entomological Society of America 98: 989-995.
Colorado potato beetle, Leptinotarsa decemlineata (Say), is the most important insect defoliator of potatoes and is infamous for its ability to develop insecticide resistance. Sperm precedence is an important consideration in developing resistance management plans. We determined the precedence of sperm from a postdiapause spring mating by using irradiated sterile males. We also investigated whether spring mating (with or without fertilization) affects reproduction of overwintered females. Precedence of sperm from spring matings versus overwintered sperm from fall matings was almost complete. Some fertilization from fall matings did take place in this experiment, but it exceeded 10% in only one of the 22 pairings. Females mated only the previous fall laid fewer eggs than spring-mated females, but spring mating did not seem to improve the hatch rate of deposited eggs. On average, mated females started laying 1.6 d sooner than fall-mated females, but this difference was not significant. Hatch rate did not change with time. Precedence of spring matings over stored sperm can help compensate for assortative summer mating among resistant individuals due to differences in developmental time between refuges and treated areas. [Full Text]

Alyokhin, A., F. A. Drummond, and G. Sewell. 2005. Density-dependent regulation in populations of potato-colonizing aphids. Population Ecology 47: 257-266.
Scarcity of long-term (over 30 years) data series represents a major challenge for an accurate estimation of the role of density-dependent processes in population regulation. We analyzed population densities of the wingless parthenogenic morphs of buckthorn aphid (BA), Aphis nasturtii Kaltenbach, potato aphid (PA), Macrosiphum euphorbiae (Thomas), and green peach aphid (GPA), Myzus persicae (Sulzer) from 1949 to 2003 for signs of density dependent regulation. We found strong evidence of density-dependent regulation, with detection of density dependence being fairly consistent among the different statistical techniques. Direct density-dependence was detected for the populations of all three species. There was also evidence of delayed density dependence for PA. The periodicity of population fluctuations for BA and GPA was 6.1 and 3.9 years, respectively. The periodicity for PA was not explicit, being highly variable throughout the time series. Effects of density-independent weather factors were relatively minor compared to density-dependent regulation. BA populations experienced a significant reduction in both density and annual oscillations starting in 1995, while GPA populations experienced a similar reduction in 1991. No such change was apparent for PA. The most likely explanation for the observed phenomenon is a change in the composition of the lady beetle community following the establishment of two alien coccinellid species, and/or changes in insecticide use by commercial growers in the area of the study. [Full Text]

Alyokhin, A. and R. Atlihan. 2005. Reduced fitness of the Colorado potato beetle (Coleoptera: Chrysomelidae) on potato plants grown in manure-amended soil. Environmental Entomology 34: 963-968.
Colorado potato beetle, Leptinotarsa decemlineata (Say), is the most important insect defoliator of potatoes worldwide. In this study, we conducted a series of no-choice assays comparing Colorado potato beetle reproduction and development on potato plants grown in manure-amended and synthetically fertilized soils. Manure-amended soil received annual applications of raw cow manure since 1991, and additional applications of cull potato compost and green manure between 1991-1998. Plants grown in manure-amended soil were inferior Colorado potato beetle hosts compared to plants grown in synthetically fertilized soil. The observed negative effects were broad in scope. Female fecundity was lower in field cages set up on manure-amended plots early in the season, although it later became comparable between the treatments. Fewer larvae survived past the first instar, and development of immature stages was slowed down on manure-amended plots. In the laboratory, first instars consumed less foliage from plants grown in manure-amended soils. These results demonstrate that organic soil management is associated with plant characteristics unfavorable for beetle reproduction and development, which should be taken into consideration when designing fully integrated crop management systems.

Alyokhin, A., G. Porter, E. Groden, and F. Drummond. 2005. Colorado potato beetle response to soil amendments: a case in support of the mineral balance hypothesis? Agriculture, Ecosystems, and Environment 109: 234-244.
The mineral balance hypothesis [Phelan, L.P., Norris, K.H., Mason, J.F., 1996. Soil management history and host preference by Ostrinia nubilalis: evidence for plant mineral balance mediating insect-plant interactions. Environ. Entomol. 25, 1329-1336] suggests that the organic matter and microbial activity associated with organically managed soils afford a buffering capability to maintain nutrient balance in plants. An optimal nutrient balance, in turn, results in both good plant growth and resistance to herbivory. Effects of soil amendment practices on Colorado potato beetle populations in potato fields and their interactions with crop rotation and two pest management approaches were investigated in the present study. Beetle densities were generally lower in plots receiving manure soil amendments in combination with reduced amounts of synthetic fertilizers compared to plots receiving full rates of synthetic fertilizers, but no manure. Crop rotation and pest management approaches had little or no effect. Unlike beetle abundance, plant height and canopy cover were comparable between plots receiving manure and synthetic fertilizer. Furthermore, tuber yields were higher in manure-amended plots. In direct accordance with the mineral balance hypothesis, there was a dramatic dissimilarity in mineral composition of potato leaves collected from manure-amended and synthetic fertilizer-treated plots. Overall, there were differences in concentrations of nitrogen, calcium, magnesium, phosphorus, aluminum, boron, copper, iron, manganese, and zinc. Boron concentration was most dramatically affected by the soil amendment. Mineral content of potato leaves explained 40-57% of the variation in the Colorado potato beetle populations observed among the experimental plots. [Full Text]

Alyokhin, A. and G. Sewell. 2004. Changes in a lady beetle community following the establishment of three alien species. Biological Invasions 6: 463-471.
A number of recent studies indicated that establishment of exotic lady beetles (Coleoptera: Coccinellidae) may have adverse affects on native lady beetle species. In the present study, we analyzed changes in coccinellid community inhabiting potato crops in northern Maine over the past 31 years. Prior to 1980, lady beetle communities were comprised almost exclusively of the two native species, Coccinella transversoguttata Brown and Hippodamia tredecimpunctata (Say). Starting 1980, an exotic species Coccinella septempunctata L. became permanently established in potato crops and quickly started to dominate lady beetle community. Two other exotic species, Harmonia axyridis (Pallas), and Propylea quatordecimpunctata (L.) became prominent members of the lady beetle community in 1995 and 1996. Invasion by exotic species was followed by a significant decline in the abundance of C. transversoguttata and H. tredecimpunctata, and a significant increase in the overall diversity of lady beetle community. The abundance of aphid prey was substantially reduced after the establishment of H. axyridis. The observed trends demonstrate the profound effects that exotic natural enemies may have on target and non-target native species, and highlight the importance of their thorough evaluation before initiating biological control programs. [Full Text]

Alyokhin, A. V., P. Yang, and R. H. Messing. 2004. Oviposition of the invasive two-spotted leafhopper on an endemic tree: Effects of an alien weed, foliar pubescence, and habitat humidity. 7pp. Journal of Insect Science, 4:13, Available online: insectscience.org/4.13.
The two-spotted leafhopper, Sophonia rufofascia (Kuoh and Kuoh), is an exotic pest from South-East Asia that attacks a wide variety of plant species in Hawaii. Myrica faya Aiton is an aggressive exotic weed that displaces and excludes native plants in Hawaiian forests. It has been argued that because of the high nutritional quality of its foliage, M. faya might facilitate leafhopper invasion of native Hawaiian ecosystems that were originally dominated by the endemic tree Metrosideros polymorpha (Gaudichaud). In the present study, we quantified suitability of M. faya and M. polymorpha as ovipositional hosts for S. rufofascia. Overall, leafhoppers preferred to deposit their eggs into the foliage of M. faya. M. faya presence in the area did not affect leafhopper oviposition on M. polymorpha. Foliar pubescence provided good protection of hirsute morphotypes of M. polymorpha. At the same time, glabrous M. polymorpha morphotypes were quite suitable for leafhopper oviposition. There was no difference in the abundance of leafhopper eggs along a precipitation gradient. Our results confirm that invasion of native Hawaiian forests by the weed M. faya will facilitate their invasion by S. rufofascia. Because of the broad host range characteristic of the two-spotted leafhopper, this build-up may adversely affect a number of endemic plant species growing in native forests. insectscience.org/4.13. [Full Text]

Messing, R., A. Alyokhin, L. Quan, C. Yiqun, and F. Xiongxi. 2003. Parasitoids of Sophonia leafhoppers in Southern China. Proceedings of the Hawaiian Entomological Society 36: 111-114.
Leafhoppers and their parasitoids in Fuzhou, China, were sampled from 1998 to 2001 in order to find their natural enemies with potential for biological control of Sophonia rufofascia in Hawaii. Eleven parasitoid species were found, of which Chaetomymar sp. (Mymaridae) were the most abundant, accounting for 65.8% of total parasitism. Parasitism of leafhopper eggs in guava orchards averaged 61.9% from April to November, with peak parasitism in September of 91.4%. [Full Text]

Alyokhin, A. and G. Sewell. 2003. On-soil movement and plant colonization by walking wingless morphs of three aphid species (Homoptera: Aphididae) in greenhouse arenas. Environmental Entomology. 32: 1393-1398.
Potato aphid (Macrosiphum euphorbiae (Thomas)), green peach aphid (Myzus persicae (Sulzer)), and buckthorn aphid (Aphis nasturtii Kaltenbach) are polyphagous herbivores that commonly colonize potato plants (Solanum tuberosum L.) in Northeastern U.S. and Canada. Their movement influences spatial and temporal patterns of viral spread within potato fields. We investigated aphid movement between potato plants early in the season, with a particular focus on their ability to walk over bare soil. On average, aphids survived 1.16?0.04 days (mean?SE) on the surface of bare soil; all of them dying within three-days. Wingless aphids did not leave potato plants that were adequate as a food supply. When forcibly removed from the host plant and released on the soil surface, all three species colonized the nearest plant within one hour. However, when given no other choice, a significant proportion of aphids was fully capable of colonizing potato plants as far as 180 cm away from the point of release. Potato aphid, which is the largest in size, was the most mobile of the three species. The green peach aphid was intermediately mobile, and the buckthorn aphid was the least mobile species. [Full Text]

Kuhar, T., J. Speese III, J. Whalen, J. Alvarez, A. Alyokhin, G. Ghidiu, and M. Spellman. 2003. Current status of insecticidal control of wireworms in potatoes. Pesticide Outlook. 14: 265-267.
No abstract available.

Alyokhin, A. V. and R.H. Messing. 2003. Parasitism of Hawaiian non-frugivorous fruit flies (Diptera: Tephritidae) by an exotic parasitoid Eurytoma tephritidis Fullaway (Hymenoptera: Eurytomidae). Proceedings of the Hawaiian Entomological Society.36: 29-37.
Eurytoma tephritidis Fullaway (Hymenoptera: Eurytomidae) is an exotic solitary larval endoparasitoid that has been recorded to parasitize gall-forming tephritids in Hawaii. We surveyed E. tephritidis parasitism of Tetreuaresta obscuriventris (Loew.), Ensina sonchi (L.), Acinia picturata (Snow), Procecidochares utilis Stone, P. alani Steyskal, Trupanea sp. nr. cratericola, and T. dubautiae (Bryan) (Diptera: Tephritidae) on four major Hawaiian islands. No wasps emerged from T. obscuriventris and E. sonchi. Among other species, percent parasitism ranged from less than 1% to over 67%, depending on fly species and sampling location. Overall, E. tephritidis showed higher affinity for gall-forming tephritids than flowerhead-feeders, although it parasitized substantial numbers of the native flower-infesting T. sp. nr. cratericola. The implications of our findings for a more accurate estimation of the risks posed by biological control programs to non-target fruit flies in Hawaii are discussed. [Full Text]

Boiteau, G., A. Alyokhin, and D. N. Ferro. 2003. The Colorado potato beetle in movement. Canadian Entomologist 135: 1-22. (Invited review article).
The recent introduction of the concept of refuge areas for the management of the Colorado potato beetle, Leptinotarsa decemlineata (Say), on resistant potato highlighted the existence of important gaps in our knowledge and understanding of this pest's dispersal. The objective of this review was to present a synthetic view of the information available for the benefit of crop managers and to identify subject areas in need of additional research. A traditional, somewhat encyclopedic, review of the old and recent literature on research methods, basics of flight and walking as well as abiotic and biotic conditions for dispersal revealed a considerable volume of information accumulated since the early 1900s. There is a consensus on the role of abiotic factors on flight and walking but a better understanding of the biotic factors will be required before the variability of the dispersal response can be fully explained or predicted. Cybernetic models of orientation proposed in the literature were pulled together into a schematic representation of the orientation process in walking L. decmlineata. The model begins the integration of the different conditions and underlying suggested mechanisms responsible for the orientation of the walking beetle. There is remarkably little information on the orientation of potato beetles during flight. Finally, the seasonality of walking and flight dispersal is reviewed in relation to the host habitat.

Alyokhin, A. V. , R.H. Messing, and and J. J. Duan. 2002. Infestation of Elephantopus mollis (Asteraceae) flowerheads by Tetreuaresta obscuriventris (Diptera: Tephritidae) on Kauai, Hawaiian Islands. Entomological News 113: 247-252.
Populations of successfully established exotic organisms rarely reach noticeable densities in their new environment, and little information is currently available on the population dynamics of the exotic insects released on the Hawaiian islands. In the present study, we surveyed present incidence of a tephritid fly of New World origin, Tetreuaresta obscuriventris (Loew.), on the island of Kauai. This fly was introduced to the island in 1961 for the biological control of an important weed species, Elephantopus mollis Kunth. Between 80 and 90% of flowerheads collected from E. mollis Kunth in our survey contained immature T. obscuriventris. An average infested flowerhead contained approximately 5.2 fly larvae. Fly populations in the surveyed areas followed aggregated distribution, and the mean number of flies per infested flowerhead was positively correlated with the percent of infested flowerheads.

Alyokhin, A., G. Sewell, and E. Groden. 2002. Aphid abundance and potato virus Y transmission in imidacloprid-treated potatoes. American Journal of Potato Research 79: 255-262.
Imidacloprid is a commonly used insecticide that is highly effective in controlling insect pests of potato. The relatively high cost of imidacloprid provides commercial growers with a strong incentive to reduce field application rates. In the present study, we investigated the impact of reduced imidacloprid rates on aphid abundance and potato virus Y transmission within potato fields. In-furrow applications of imidacloprid provided better aphid control even at a reduced rate when compared to threshold-based foliar applications, but did not suppress the spread of the non-persistently transmitted potato virus Y. Virus transmission was significantly decreased in foliar-sprayed plots, possibly because foliar applications disrupted virus acquisition by aphid vectors. Despite these generally encouraging results, we still observed 2.3 ? 2.7 fold increase in virus infection at foliar-treated plots at the end of the growing season.

Yang, P., D. Foote, A. Alyokhin, L. Lenz, and R. Messing. 2002. Distribution and abundance of mymarid parasitoids (Hymenoptera: Mymaridae) of the two-spotted leafhopper (Homoptera: Cicadellidae) in Hawaii. Biological Control 23: 237-244.
The abundance of mymarid parasitoids attacking the two-spotted leafhopper (Sophonia rufofascia [Kuoh and Kuoh]), a polyphagous pest recently adventive to Hawaii, was monitored using yellow sticky cards deployed in several areas on the islands of Kauai and Hawaii. The yellow cards captured Chaetomymar sp. nr bagicha Narayanan, Subba Rao, & Kaur and Schizophragma bicolor (Dozier), both adventive species; as well as Polynema sp. Haliday, which is endemic to Hawaii (Hymenoptera: Mymaridae). The former two species were most abundant at all sites. On Kauai, there was a negative correlation between the captures of C. sp. nr bagicha and Polynema sp. Throughout the season, the increase in parasitoid numbers generally followed the increase in leafhopper numbers. C. sp. nr. bagicha and S. bicolor showed distinct habitat preferences. Removal of Myrica faya Aiton, an invasive weed that is a highly preferred two-spotted leafhopper host, decreased the overall numbers of captured parasitoids, but lead to a two-fold increase in the ratio of trapped parasitoids/hosts in weed-free areas.

Alyokhin, A. V., P. Yang, and R. H. Messing. 2001. Distribution and parasitism of two-spotted leafhopper eggs (Homoptera: Cicadellidae) in Hawaii. Annals of the Entomological Society of America 94: 664-669.
The two-spotted leafhopper, Sophonia rufofascia (Kuoh and Kuoh), is a recent invasive pest attacking a wide variety of plant species in Hawaii. We surveyed the distribution and parasitism of its eggs in a number of natural and agricultural habitats on the islands of Kauai, Oahu, and Hawaii. Egg density was fairly low, with egg distribution affected both by plant species and plant habitat. Approximately 40% of S. rufofascia eggs, averaged over all plants and sites, were parasitized by Chaetomymar sp. nr bagichi Narayanan, Subba Rao, & Kaur; Schizophragma bicolor (Dozier); and Polynema sp. Haliday (Hymenoptera: Mymaridae). Percent parasitism varied widely among different plant species and habitats. Ch. sp. nr. bagichi was the most abundant and widely distributed species, but the parasitoid guild varied depending on plant and on habitat. The implications of these results on decisions regarding classical biological control of two-spotted leafhopper in Hawaii are discussed. [Full Text]

Alyokhin, A. V., R. H. Messing, and J. J. Duan. 2001. Utilization of the exotic weed Pluchea odorata (Asteraceae) and related plants by the introduced biological control agent Acinia picturata (Diptera: Tephritidae) in Hawaii. Biocontrol Science and Technology 11: 711-718.
The flower-head feeding fly Acinia picturata (Diptera: Tephritidae) was deliberately introduced from Mexico into Hawaii in 1959 for biological control of the exotic weed Pluchea odorata (Snow) (Asteraceae). Neither field efficacy nor possible non-target effects of the fly have been evaluated in the 40 years since the introduction. We assessed the impact of the fly on both its target host and on 7 non-target plant species. The impact on the target weed was limited, with only 5 - 13% of the developing seeds in P. odorata flowerheads being destroyed by larval feeding. We did not detect any host range expansion of A. picturata onto flowerheads of 2 exotic or 5 endemic non-target plant species in the family Asteraceae. [Full Text]

Alyokhin, A. V. and R. H. Messing. 2001. Association of Trupanea dubautiae (Diptera: Tephritidae) with Dubautia laxa (Asteraceae) in Mt. Kaala National Area Reserve on Oahu. Proceedings of the Hawaiian Entomological Society 35: 137-139.
No abstract available [Full Text]

Yang, P., A. V. Alyokhin, and R. H. Messing. 2001. Patterns of oviposition and parasitism of eggs of Kallitaxila granulata (Homoptera: Tropiduchidae), a newly invasive planthopper in Hawaii. Proceedings of the Hawaiian Entomological Society 35: 77-83.
Kallitaxila granulata (Stal) (Homoptera: Tropiduchidae), a recent invasive species in Hawaii, is a potential pest of agricultural and forest ecosystems. We present information on the planthopper's oviposition behavior, its egg distribution patterns, and the occurrence of egg parasitoids in Hawaii. There were no differences in the percentage of leaves containing K. granulata oviposition scars or in the number of eggs per scar among 4 different host plants (guava, hapuu, uluhe and kukui) at 3 different sites. However, there were substantial differences in patterns of egg distribution among the host plants. The planthopper preferred to lay eggs into the veins and to oviposit clutches of eggs in clusters on guava plants, while it tended to lay eggs singly into the veins on hapuu. On kukui, eggs were deposited equally in or off the veins, and were mostly deposited singly. On all 3 host plants, eggs conformed to a negative binomial distribution. Two species of parasitoids were reared from K. granulata eggs: Chaetomymar sp. near bagicha (a common parasitoid of the twospotted leafhopper, Sophonia rufofascia), and Telenomus sp. (Hymenoptera: Scelionidae). Total parasitism differed among host plants and sites with a range of 0 to 18.5%. [Full Text]

Alyokhin, A. V., R. H. Messing, and J. J. Duan. 2001. Abundance and mating behavior of Oriental fruit flies (Diptera: Tephritidae) in the vicinity of methyleugenol-baited traps. Pan-Pacific Entomologist 77: 161-167.
Methyleugenol-baited traps are used for Oriental fruit fly control through male annihilation, as well as for detection and monitoring of fly populations. However, if the males which come to these traps emit sex pheromones, attract females from the surrounding vegetation, and mate with them before being killed, then using such traps might in fact increase levels of fruit infestation. In the present study, we monitored fly abundance in an experimental orchard before, during, and after methyleugenol-baited trap deployment. We also recorded the numbers of flies recruited to the trees with and without traps, and quantified their sexual activity. The males attracted by methyleugenol in our experiments fed on the poisoned baits almost immediately upon their arrival, and did not attempt to emit pheromones or attempt copulations before entering the traps. No changes in female abundance in the vicinity of deployed traps were recorded. Because of their high specificity, low cost, and environmental safety, methyleugenol-baited traps might be a valuable tool for integrated management of Oriental fruit fly populations.

Alyokhin, A. V., C. Mille, R. H. Messing, and J. J. Duan. 2001. Selection of pupation habitats by Oriental fruit fly larvae in the laboratory. Journal of Insect Behavior 14: 57-67.
We performed a series of laboratory experiments to determine the effects of shade, soil moisture, and soil compaction on the selection of pupation habitats by wandering late instar Oriental fruit flies, Bactrocera dorsalis (Hendel). Larvae showed a strong preference towards pupating in shaded rather than brightly lit areas, in moist rather than dry soil, and in soil with larger particle sizes. These behavioral preferences are likely to lead to clumped distribution of Oriental fruit fly pupae in natural habitats. The implications of this for management of localized populations by chemical and biological methods are discussed.

Alyokhin, A. V, R. H. Messing, and J. J. Duan. 2000.Visual and olfactory stimuli and fruit maturity affect trap captures of Oriental fruit flies (Diptera: Tephritidae). Journal of Economic Entomology 93: 644-649.
An effective lure-and-kill trap is a potentially important instrument in monitoring and controlling Oriental fruit flies, Bactrocera dorsalis(Hendel). A number of experiments were performed in a commercial guava (Psydium guajava L.) orchard to determine how fly captures are affected by combining visual and olfactory stimuli, and by the timing of trap deployment relatively to host phenology. Baiting sticky Ladd traps with hydrolyzed liquid protein significantly increased the number of captured flies. Mostly male flies were caught in the absence of mature guava fruit, while mostly female flies were caught when ripe fruit was abundant. These results suggest that an effective Oriental fruit fly trap should include both visual and olfactory lures, and that proper timing of trap deployment can be an important factor in monitoring female abundance in Oriental fruit fly populations. [Full Text]

Alyokhin, A. V., D. N. Ferro, C. W. Hoy, and G. Head. 1999. Laboratory assessment of flight activity displayed by the Colorado potato beetles (Coleoptera: Chrysomelidae) fed on transgenic and Cry3A toxin-treated potato foliage. Journal of Economic Entomology 92: 115-120.
Adults of full-sib Colorado potato beetle families were separated into three groups fed on different diets: transgenic potato foliage, potato foliage treated with a foliar formulation of B. thuringiensis endotoxin (12.37 ?g of Cry3A d-endotoxin per 1?l of mixture), and untreated potato foliage. After feeding for 3 hours, all the beetles were placed on a computer-linked flight mill system. The number of beetles that flew, duration of each flight, and the number of flights for each beetle were recorded. Feeding on transgenic foliage had a strong negative effect on the proportion of beetles that flew, as well as the average number of flights per flying beetle. Mean flight duration was not influenced by the beetle diet, but interaction between family and diet was highly significant, with pronounced family effects observed for the beetles fed on standard and treated foliage. Beetles from families that performed the longest flights when fed on untreated foliage performed the shortest flights when fed on transgenic foliage. Suppression of beetle flight as a result of endotoxin ingestion could keep beetles within transgenic fields, thus increasing selection pressure towards development of physiological resistance. One possible way to reduce this pressure is to provide refugia for susceptible beetles in close association with fields planted to transgenic potato. [Full Text]

Alyokhin, A.V. and D. N. Ferro. 1999. Electrophoretic confirmation of sperm mixing in mated Colorado potato beetles (Coleoptera: Chrysomelidae). Annals of the Entomological Society of America 92: 230-235.
Sperm precedence in the Colorado potato beetle, Leptinotarsa decemlineata (Say), was investigated using phosphoglucomutase (Pgm) allozymes as genetic markers. Females were mated to two males carrying different Pgm alleles, and the proportion of offspring sired by each male was determined by cellulose acetate gel electrophoresis. Our results indicate that Pgm alleles in the Colorado potato beetle are inherited in the Mendelian fashion, and there is no change in sperm utilization over time. We were also able to confirm that sperm precedence in this insect is incomplete, with about 72% of the larvae fathered by males at the second mating. Possible implications of incomplete sperm precedence for insecticide resistance management are discussed. [Full Text]

Alyokhin, A. V. and D. N. Ferro. 1999. Modifications in flight and oviposition of Bt-resistant and Bt-susceptible Colorado potato beetles as a result of exposure to Bacillus thuringiensis subsp. tenebrionis Cry3A toxin. Entomologia Experimentalis et Applicata 90: 93-101.
Laboratory strains of Colorado potato beetle, Leptinotarsa decemlineata (Say), physiologically resistant and susceptible to Bacillus thuringiensis (Berliner) subsp. tenebrionis Cry3A toxin were reared to adults on caged potato plants. Influence of three different diets (transgenic potatoes, regular potatoes, and regular potatoes followed by the transgenic potatoes) on beetle mortality, fecundity, and flight behavior were tested under laboratory conditions. A computer-linked flight mill system was used to quantify beetle flight, and dissections were performed to determine the level of flight muscle development. Susceptible beetles continuously fed on transgenic foliage suffered heavy mortality, did not develop flight muscles, and did not produce any eggs. Resistant beetles continuously fed on transgenic foliage were capable of flight and reproduction; however, it took them longer to initiate flight behavior, and their fecundity was lower than fecundity of other treatments. In both strains, detrimental effects became significantly less severe when the beetles were allowed to feed on regular foliage prior to toxin ingestion. In the resistant strain, ingestion of Cry3A toxin significantly increased flight activity, indicating that physiological resistance was probably reinforced by the behavioral escape from toxic environments. No such response was observed for susceptible beetles. When fed on regular foliage, resistant Colorado potato beetles engaged in significantly fewer flights than susceptible beetles. Behavioral differences between resistant and susceptible beetles observed in the present study are likely to affect gene flow between transgenic crops and adjacent refugia, and should be taken in consideration when designing resistance management plans for transgenic potato crops.

Alyokhin, A. V. and D. N. Ferro. 1999. Reproduction and dispersal of summer-generation Colorado potato beetle (Coleoptera: Chrysomelidae). Environmental Entomology 28: 425-430.
Colorado potato beetle dispersal and reproduction was investigated under field and laboratory conditions. Movement and mating of newly emerged summer-generation Colorado potato beetle adults was monitored in the field using a mark-recapture technique, and beetle mating within experimental plots was recorded. The number of degree-days (DD) required for the beetles to become reproductive was tested in an environmental chamber using 10° C as a developmental threshold. A computer-linked flight mill system was used to quantify the influence of mating on the flight behavior of male and female beetles. Adult dispersal started within the first 24 hours after eclosion from the pupae, but a significant proportion of newly emerged beetles stayed close to the place of their larval development until reaching reproductive maturity. The beetles required at least 34 DD before mating produced viable offspring, and females did not start laying eggs until a minimum of 51 DD after eclosion. Mating had a pronounced effect on beetle flight, decreasing flight activity of the females and increasing flight activity of the males. Enhancing gene flow between beetles surviving on transgenic plants and susceptible beetles in refugia should be advantageous in managing beetle resistance to transgenic plants. [Full Text]

Alyokhin, A. V. and D. N. Ferro. 1999. Relative fitness of Colorado potato beetle (Coleoptera: Chrysomelidae) resistant and susceptible to the Bacillus thuringiensis Cry3A toxin. Journal of Economic Entomology 92: 510-515.
Laboratory experiments were conducted to compare relative fitness of strains of Colorado potato beetle resistant and susceptible to Bacillus thuringiensis subsp. tenebrionis Cry3A toxin. Net replacement rates and intrinsic rates of population increase were calculated for resistant and susceptible populations. During the experiment, susceptible males on average copulated 13.3 ± 1.5 times, while resistant males copulated only 8.0 ± 1.0 times. Susceptible females produced an average of 824.2 ± 68.1 eggs and 590.9 ± 58.5 larvae, which was significantly more than 484.6 ± 48.0 eggs and 334.9 ± 39.7 larvae produced by an average resistant female. As a result, both net replacement rate and intrinsic rate of increase were reduced for the resistant population. Furthermore, twice as many susceptible beetles as resistant beetles survived overwintering diapause. Our results clearly indicate that relative fitness of resistant individuals is reduced in the absence of Bacillus thuringiensis in the environment. Therefore, relaxation of selection pressure through refugia and insecticide rotation will favor decrease in the frequency of resistant alleles in beetle populations. [Full Text]

Alyokhin, A. V. and D. N. Ferro. 1999. Mating ability of Colorado potato beetle (Coleoptera: Chrysomelidae) males fed transgenic potato foliage. Canadian Entomologist 131: 539-540.
Thirty-three teneral Colorado potato beetle males were provided with non-transgenic foliage for 8 d, another 33 males were provided with non-transgenic foliage for 4 days, and then switched to transgenic foliage for another 4 d, and the remaining 33 males were provided with transgenic foliage for 8 days and then mated to females continuously fed on non-transgenic foliage only. Seventy-five percent of the males continuously fed transgenic foliage died during the first 8 d after eclosion. Only one of the females that mated to surviving males laid a single mass of fertile eggs, producing a total of 14 larvae. All the males from the other two treatments survived throughout the experiment. Ninety-four percent of the males fed non-transgenic foliage and 85% of the males fed both non-transgenic and transgenic foliage sired viable offspring. On average, one fertile female mated to a male fed non-transgenic foliage produced 353.3 eggs (SE=15.9) giving rise to 248.6 larvae (SE=15.9), and one fertile female mated to a male fed both on non-transgenic and transgenic foliage produced 322.9 eggs (SE=22.9) giving rise to 218.9 larvae (SE=18.1). Neither mean number of eggs, nor mean number of larvae was significantly different between the treatments. These results indicate that susceptible Colorado potato beetle males arriving in transgenic potato fields from refugia can mate with resident resistant females.

Ferro, D. N., A. V. Alyokhin, and D. B. Tobin. 1999. Reproductive status and flight activity of the overwintered Colorado potato beetle. Entomologia Experimentalis et Applicata 91: 443-448.
Mating behavior of post-diapause Colorado potato beetles, Leptinotarsa decemlineata (Say), was observed within an overwintering site, a rotated potato field, newly colonized potato plants, and under laboratory conditions. The influence of spring mating on beetle flight in the presence and in the absence of host plants was investigated using a computer-linked flight mill system. Diapause was terminated simultaneously in male and female beetles, and the first matings were observed as early as within the first 24 hours after the beetles emerged from the soil (60-90 DD accumulated). The beetles mated within the overwintering site, the potato field, and the fields rotated out of potatoes. Mating status did not affect flight behavior of overwintered beetles; however, unfed beetles displayed higher flight activity than fed beetles. Most flight activity took place soon after flight muscle regeneration, and then declined sharply by the 5th day after flight initiation. Mating in or near overwintering sites soon after diapause termination might be an important factor in providing gene flow between insecticide-resistant and insecticide-susceptible Colorado potato beetle populations, and should be considered in designing resistance management plans.