Selection and characterization of spinetoram resistance in field collected Drosophila melanogaster.

Insecticides are commonly employed in vineyards to control vinegar flies and limit sour rot disease. Widespread resistance to available insecticides is having a negative impact on managing Drosophila melanogaster populations, rendering control of sour rot more difficult. An insecticide registered for use in vineyards to which resistance is not yet widespread (at least in New York and Missouri) is spinetoram. Spinetoram targets the nicotinic acetylcholine receptor α6, and mutations in α6 have been associated with resistance in some insects. Our goals were to select for a spinetoram resistant strain of D. melanogaster (starting with field collected populations), characterize the resistance, and identify the mutation responsible. After five selections a strain (SpinR) with >190-fold resistance was obtained. Resistance could not be overcome by insecticide synergists, suggesting an altered target site was involved. We cloned and sequenced the α6 allele from the spinetoram resistant strain and identified a mutation causing a glycine to alanine change at amino acid 301 (equivalent position to the G275E mutation found in some spinosad/spinetoram resistant insects). This mutation was found at low levels in field populations, but increased with each selection until it became homozygous in SpinR. We discuss how the identification of the spinetoram resistance mutation can be used for resistance management.

The Three-Cornered Alfalfa Hopper, Spissistilus festinus, Is a Vector of Grapevine Red Blotch Virus in Vineyards.

Spissistilus festinus (Hemiptera: Membracidae) transmit grapevine red blotch virus (GRBV, Grablovirus, Geminiviridae) in greenhouse settings; however, their role as a vector of GRBV in vineyards is unknown. Following controlled exposures of aviruliferous S. festinus for two weeks on infected, asymptomatic vines in a California vineyard in June and a 48 h gut clearing on alfalfa, a nonhost of GRBV, approximately half of the released insects tested positive for GRBV (45%, 46 of 102), including in the salivary glands of dissected individuals (11%, 3 of 27), indicating acquisition. Following controlled exposures of viruliferous S. festinus for two to six weeks on GRBV-negative vines in vineyards in California and New York in June, transmission of GRBV was detected when two S. festinus were restricted to a single leaf (3%, 2 of 62 in California; 10%, 5 of 50 in New York) but not with cohorts of 10-20 specimens on entire or half shoots. This work was consistent with greenhouse assays in which transmission was most successful with S. festinus exposed to a single leaf (42%, 5 of 12), but rarely occurred on half shoots (8%, 1 of 13), and never on entire shoots (0%, 0 of 18), documenting that the transmission of GRBV is facilitated through the feeding of fewer S. festinus on a restricted area of grapevine tissue. This work demonstrates S. festinus is a GRBV vector of epidemiological importance in vineyards.

Molecular and behavioral studies reveal differences in olfaction between winter and summer morphs of Drosophila suzukii.

Spotted-wing drosophila, Drosophila suzukii (Matsumura), is a major economic pest of several fruit crops in Europe, North and South America, and other parts of the world because it oviposits in ripening thin-skinned fruits. This vinegar fly exhibits two distinct morphotypes: a summer and a winter morph. Although adaptations associated with the winter morph enhance this invasive pest's capacity to survive in cold climates, winter is still a natural population bottleneck. Since monitoring early spring populations is important for accurate population forecasts, understanding the winter morph's response to olfactory cues may improve current D. suzukii management programs. In this study, a comparative transcriptome analysis was conducted to assess gene expression differences between the female heads of the two D. suzukii morphs, which showed significant differences in 738 genes (p ≤ 0.0001). Out of twelve genes related to olfaction determined to be differentially expressed in the transcriptome, i.e., those related to location of food sources, chemosensory abilities, and mating behavior, nine genes were upregulated in the winter morph while three were downregulated. Three candidate olfactory-related genes that were most upregulated or downregulated in the winter morph were further validated using RT-qPCR. In addition, behavioral assays were performed at a range of temperatures to confirm a differing behavioral response of the two morphs to food odors. Our behavioral assays showed that, although winter morphs were more active at lower temperatures, the summer morphs were generally more attracted to food odors. This study provides new insights into the molecular and behavioral differences in response to olfactory cues between the two D. suzukii morphs that will assist in formulating more effective monitoring and physiological-based control tools.

Transmission of Grapevine Red Blotch Virus by Spissistilus festinus [Say, 1830] (Hemiptera: Membracidae) between Free-Living Vines and Vitis vinifera 'Cabernet Franc'.

Grapevine red blotch disease emerged within the past decade, disrupting North American vine stock production and vineyard profitability. Our understanding of how grapevine red blotch virus (GRBV), the causal agent of the disease, interacts with its Vitis hosts and insect vector, Spissistilus festinus, is limited. Here, we studied the capabilities of S. festinus to transmit GRBV from and to free-living vines, identified as first-generation hybrids of V. californica and V. vinifera 'Sauvignon blanc' (Vcal hybrids), and to and from V. vinifera 'Cabernet franc' (Vvin Cf) vines. The transmission rate of GRBV was high from infected Vcal hybrid vines to healthy Vcal hybrid vines (77%, 10 of 13) and from infected Vvin Cf vines to healthy Vcal hybrid vines (100%, 3 of 3). In contrast, the transmission rate of GRBV was low from infected Vcal hybrid vines to healthy Vvin Cf vines (15%, 2 of 13), and from infected Vvin Cf vines to healthy Vvin Cf vines (19%, 5 of 27). No association was found between transmission rates and GRBV titer in donor vines used in transmission assays, but the virus titer was higher in the recipient leaves of Vcal hybrid vines compared with recipient leaves of Vvin Cf vines. The transmission of GRBV from infected Vcal hybrid vines was also determined to be trans-stadial. Altogether, our findings revealed that free-living vines can be a source for the GRBV inoculum that is transmissible by S. festinus to other free-living vines and a wine grape cultivar, illustrating the interconnected roles of the two virus hosts in riparian areas and commercial vineyards, respectively, for virus spread. These new insights into red blotch disease epidemiology will inform the implementation of disease management strategies.

Does Habituation Affect the Efficacy of Semiochemical Oviposition Repellents Developed Against Drosophila suzukii?

The application of feeding and oviposition repellents is limited to arthropod systems in which habituation does not occur. Although several compounds appear to reduce Drosophila suzukii Matsumura (Dipetra: Drosophilidae) oviposition in berries, previous studies have yet to address whether habituation is a significant risk following preexposure. We tested the response of adult female D. suzukii to three previously identified semiochemical oviposition repellents, 1-octen-3-ol (octenol), ±-geosmin, and 2-n-pentylfuran, following adult and larval preexposure. Using a two-choice gated trap capture assay, we assessed captures in repellent-treated versus blank traps, female survival, and oviposition frequency in the selected trap. We did not find evidence of habituation to octenol or 2-pentylfuran in adult flies preexposed for 24, 48, or 72 hr. When exposed to each of the repellents as larvae, D. suzukii showed similar deterrence as those exposed as adults alone. However, mortality did decrease in F1 octenol treated flies. In contrast with previous investigations we did not observe repellent effects in response to geosmin. Our results suggest that neither exposure during the adult life stage nor during larval development inhibited the effectiveness of octenol and 2-pentylfuran. However, greater survivorship on octenol treated baits in F1 flies, combined with apparent neurotoxic effects of this compound, indicate that octenol may be less suited for field applications. For this reason, 2-pentylfuran appears to be a better candidate for ongoing research aimed at developing an effective push-pull system of behavioral management.

The Effect of Erwinia amylovora Infection in Apple Saplings and Fruit on the Behavior of Delia platura (Diptera: Anthomyiidae).

The Vector Manipulation Hypothesis (VMH) posits that phytopathogens develop strategies to enhance dissemination by mediating behavior change in insect vectors. The VMH is poorly studied in phytopathogenic bacteria, especially in systems with numerous, occasional vectors. Erwinia amylovora is a bacterial pathogen of pome fruit that produces a bacterial ooze and is mechanically vectored by insects after they feed on ooze. The blossom blight phase of the disease exhibits manipulation of honeybees, leading to enhanced transmission, but whether the same occurs during the shoot blight phase of the disease is unknown. The goal of this study was to evaluate the effect of E. amylovora on the behavior of Delia platura, a fly with a worldwide endemic presence that may transmit E. amylovora. We show that D. platura prefer infected, oozing fruit to uninfected fruit in choice tests and that preference subsides when bacterial ooze is removed from the infected fruit. Flies did not exhibit a preference between infected saplings and uninfected saplings. The volatiles of infected fruit did not attract D. platura, indicating that diseased fruit odor is not responsible for the observed preference for infected fruit. Flies did not differentiate between sapling odors until infected trees had died, at which point they preferred uninfected tree odors. This study supports previous hypotheses suggesting that E. amylovora takes advantage of existing plant-insect interactions, though it is not fully understood how significantly behavioral changes affect transmission. Additional pathosystems with occasional, nonspecific vectors should be studied to further understanding of the VMH.

Evaluation of RNA Interference for Control of the Grape Mealybug Pseudococcus maritimus (Hemiptera: Pseudococcidae).

The grape mealybug Pseudococcus maritimus (Ehrhorn, 1900) (Hemiptera: Pseudococcidae) is a significant pest of grapevines (Vitis spp.) and a vector of disease-causing grape viruses, linked to its feeding on phloem sap. The management of this pest is constrained by the lack of naturally occurring resistance traits in Vitis. Here, we obtained proof of concept that RNA interference (RNAi) using double-stranded RNA (dsRNA) molecules against essential genes for phloem sap feeding can depress insect survival. The genes of interest code for an aquaporin (AQP) and a sucrase (SUC) that are required for osmoregulation in related phloem sap-feeding hemipteran insects (aphids and whiteflies). In parallel, we investigated the grape mealybug genes coding non-specific nucleases (NUC), which reduce RNAi efficacy by degrading administered dsRNA. Homologs of AQP and SUC with experimentally validated function in aphids, together with NUC, were identified in the published transcriptome of the citrus mealybug Planococcus citri by phylogenetic analysis, and sequences of the candidate genes were obtained for Ps. maritimus by PCR with degenerate primers. Using this first sequence information for Ps. maritimus, dsRNA was prepared and administered to the insects via an artificial diet. The treatment comprising dsRNA against AQP, SUC and NUC significantly increased insect mortality over three days, relative to dsRNA-free controls. The dsRNA constructs for AQP and NUC were predicted, from sequence analysis to have some activity against other mealybugs, but none of the three dsRNA constructs have predicted activity against aphids. This study provides the basis to develop in planta RNAi strategies against Ps. maritimus and other mealybug pests of grapevines.

Seasonal polyphenism of spotted-wing Drosophila is affected by variation in local abiotic conditions within its invaded range, likely influencing survival and regional population dynamics.

Overwintering Drosophila often display adaptive phenotypic differences beneficial for survival at low temperatures. However, it is unclear which morphological traits are the best estimators of abiotic conditions, how those traits are correlated with functional outcomes in cold tolerance, and whether there are regional differences in trait expression.We used a combination of controlled laboratory assays, and collaborative field collections of invasive Drosophila suzukii in different areas of the United States, to study the factors affecting phenotype variability of this temperate fruit pest now found globally.Laboratory studies demonstrated that winter morph (WM) trait expression is continuous within the developmental temperature niche of this species (10-25°C) and that wing length and abdominal melanization are the best predictors of the larval abiotic environment.However, the duration and timing of cold exposure also produced significant variation in development time, morphology, and survival at cold temperatures. During a stress test assay conducted at -5°C, although cold tolerance was greater among WM flies, long-term exposure to cold temperatures as adults significantly improved summer morph (SM) survival, indicating that these traits are not controlled by a single mechanism.Among wild D. suzukii populations, we found that regional variation in abiotic conditions differentially affects the expression of morphological traits, although further research is needed to determine whether these differences are genetic or environmental in origin and whether thermal susceptibility thresholds differ among populations within its invaded range.

Response of Wild Spotted Wing Drosophila (Drosophila suzukii) to Microbial Volatiles.

The olfactory cues used by various animals to detect and identify food items often include volatile organic compounds (VOCs) produced by food-associated microorganisms. Microbial VOCs have potential as lures to trap animal pests, including insect crop pests. This study investigated microorganisms whose VOCs are attractive to natural populations of the spotted wing drosophila (SWD), an invasive insect pest of ripening fruits. The microorganisms readily cultured from wild SWD and SWD-infested fruits included yeasts, especially Hanseniaspora species, and various bacteria, including Proteobacteria (especially Acetobacteraceae and Enterobacteriaceae) and Actinobacteria. Traps in a raspberry planting that were baited with cultures of Hanseniaspora uvarum, H. opuntiae and the commercial lure Scentry trapped relatively high numbers of both SWD and non-target drosophilids. The VOCs associated with these baits were dominated by ethyl acetate and, for yeasts, other esters. By contrast, Gluconobacter species (Acetobacteraceae), whose VOCs were dominated by acetic acid and acetoin and lacked detectable ethyl acetate, trapped 60-75% fewer SWD but with very high selectivity for SWD. VOCs of two other taxa tested, the yeast Pichia sp. and Curtobacterium sp. (Actinobacteria), trapped very few SWD or other insects. Our demonstration of among-microbial variation in VOCs and their attractiveness to SWD and non-pest insects under field conditions provides the basis for improved design of lures for SWD management. Further research is required to establish how different microbial VOC profiles may function as reliable cues of habitat suitability for fly feeding and oviposition, and how this variation maps onto among-insect species differences in habitat preference.

Interactions among morphotype, nutrition, and temperature impact fitness of an invasive fly.

Invasive animals depend on finding a balanced nutritional intake to colonize, survive, and reproduce in new environments. This can be especially challenging during situations of fluctuating cold temperatures and food scarcity, but phenotypic plasticity may offer an adaptive advantage during these periods. We examined how lifespan, fecundity, pre-oviposition periods, and body nutrient contents were affected by dietary protein and carbohydrate (P:C) ratios at variable low temperatures in two morphs (winter morphs WM and summer morphs SM) of an invasive fly, Drosophila suzukii. The experimental conditions simulated early spring after overwintering and autumn, crucial periods for survival. At lower temperatures, post-overwintering WM lived longer on carbohydrate-only diets and had higher fecundity on low-protein diets, but there was no difference in lifespan or fecundity among diets for SM. As temperatures increased, low-protein diets resulted in higher fecundity without compromising lifespan, while high-protein diets reduced lifespan and fecundity for both WM and SM. Both SM and WM receiving high-protein diets had lower sugar, lipid, and glycogen (but similar protein) body contents compared to flies receiving low-protein and carbohydrate-only diets. This suggests that flies spend energy excreting excess dietary protein, thereby affecting lifespan and fecundity. Despite having to recover from nutrient depletion after an overwintering period, WM exhibited longer lifespan and higher fecundity than SM in favorable diets and temperatures. WM exposed to favorable low-protein diet had higher body sugar, lipid, and protein body contents than SM, which is possibly linked to better performance. Although protein is essential for oogenesis, WM and SM flies receiving low-protein diets did not have shorter pre-oviposition periods compared to flies on carbohydrate-only diets. Finding adequate carbohydrate sources to compensate protein intake is essential for the successful persistence of D. suzukii WM and SM populations during suboptimal temperatures.

Effects of Exposure Time and Biological State on Acquisition and Accumulation of Erwinia amylovora by Drosophila melanogaster.

Fire blight, caused by the bacterium Erwinia amylovora, is a disease devastating the production of rosaceous crops, primarily apple and pear, with worldwide distribution. Fire blight begins in the spring when primary inoculum is produced as ooze, which consists of plant sap, E. amylovora, and exopolysaccharides. Ooze is believed to be transferred to healthy tissues by wind, rain, and insects. However, the mechanisms by which insects locate and transmit ooze are largely undocumented. The goals of this study were to investigate the biological factors affecting acquisition of E. amylovora from ooze by a model dipteran, Drosophila melanogaster, and to determine whether flies are able to mechanically transfer this bacterium after acquisition. We found that the percentage of positive flies increased as exposure time increased, but nutritional state, mating status, and sex did not significantly alter the number of positive individuals. Bacterial abundance was highly variable at all exposure times, suggesting that other biological factors play a role in acquisition. Nutritional state had a significant effect on E. amylovora abundance, and food-deprived flies had higher E. amylovora counts than satiated flies. We also demonstrated that D. melanogaster transmits E. amylovora to a selective medium surface and hypothesize that the same is possible for plant surfaces, where bacteria can persist until an opportunity to colonize the host arises. Collectively, these data suggest a more significant role for flies than previously thought in transmission of fire blight and contribute to a shift in our understanding of the E. amylovora disease cycle.IMPORTANCE A recent hypothesis proposed that dissemination of Erwinia amylovora from ooze by flies to native rosaceous trees was likely key to the life cycle of the bacterium during its evolution. Our study validates an important component of this hypothesis by showing that flies are capable of acquiring and transmitting this bacterium from ooze under various biotic conditions. Understanding how dipterans interact with ooze advances our current knowledge of its epidemiological function and provides strong evidence for an underappreciated role of flies in the disease cycle. These findings may be especially important as they pertain to shoot blight, because this stage of the disease is poorly understood and may involve a significant amount of insect activity. Broadly, this study underscores a need to consider the depth, breadth, and origin of interactions between flies and E. amylovora to better understand its epidemiology.

Insecticide Resistance in Drosophila melanogaster (Diptera: Drosophilidae) is Associated with Field Control Failure of Sour Rot Disease in a New York Vineyard.

Sour rot is a complex disease of grapes caused by an interaction of yeast, acetic acid bacteria, and Drosophila spp. Application of insecticides (most commonly zeta-cypermethrin) targeting Drosophila has previously provided substantial control of sour rot in wine grapes of New York vineyards. In harvest season of 2018, a control failure of sour rot and high populations of Drosophila, mostly Drosophila melanogaster, were observed in a vineyard in the Finger Lakes region, NY, despite repeated applications of zeta-cypermethrin (Mustang Maxx). To determine if resistance was responsible for the control failure, we quantified the toxicity of zeta-cypermethrin and the four other insecticides registered for Drosophila control in NY vineyards. Diagnostic concentrations (susceptible strain LC95, 4 × LC95, and 16 × LC95) were used to evaluate percentage survival of the field flies relative to the susceptible Canton-S strain. Resistance to zeta-cypermethrin, acetamiprid, and malathion, but not to spinosad and spinetoram, was observed in the field-collected flies. This study provides evidence that insecticide resistance of Drosophila is associated with control failure of sour rot in some vineyards, and directly influencing grape production. The implications of these results to insecticide resistance monitoring and management are discussed.

Agriculturally dominated landscapes reduce bee phylogenetic diversity and pollination services.

Land-use change threatens global biodiversity and may reshape the tree of life by favoring some lineages over others. Whether phylogenetic diversity loss compromises ecosystem service delivery remains unknown. We address this knowledge gap using extensive genomic, community, and crop datasets to examine relationships among land use, pollinator phylogenetic structure, and crop production. Pollinator communities in highly agricultural landscapes contain 230 million fewer years of evolutionary history; this loss was strongly associated with reduced crop yield and quality. Our study links landscape-mediated changes in the phylogenetic structure of natural communities to the disruption of ecosystem services. Measuring conservation success by species counts alone may fail to protect ecosystem functions and the full diversity of life from which they are derived.

Landscape context shifts the balance of costs and benefits from wildflower borders on multiple ecosystem services.

In the face of global biodiversity declines driven by agricultural intensification, local diversification practices are broadly promoted to support farmland biodiversity and multiple ecosystem services. The creation of flower-rich habitats on farmland has been subsidized in both the USA and EU to support biodiversity and promote delivery of ecosystem services. Yet, theory suggests that the landscape context in which local diversification strategies are implemented will influence their success. However, few studies have empirically evaluated this theory or assessed the ability to support multiple ecosystem services simultaneously. Here, we evaluate the impact of creating flower-rich habitats in field margins on pollination, pest control, and crop yield over 3 years using a paired design across a landscape gradient. We find general positive effects of natural habitat cover on fruit weight and that flowering borders increase yields by promoting bee visitation to adjacent crops only in landscapes with intermediate natural habitat cover. Flowering borders had little impact on biological control regardless of landscape context. Thus, knowledge of landscape context can be used to target wildflower border placement in areas where they will have the greatest likelihood for success and least potential for increasing pest populations or yield loss in nearby crops.

Landscape simplification reduces classical biological control and crop yield.

Agricultural intensification resulting in the simplification of agricultural landscapes is known to negatively impact the delivery of key ecosystem services such as the biological control of crop pests. Both conservation and classical biological control may be influenced by the landscape context in which they are deployed; yet studies examining the role of landscape structure in the establishment and success of introduced natural enemies and their interactions with native communities are lacking. In this study, we investigated the relationship between landscape simplification, classical and conservation biological control services and importantly, the outcome of these interactions for crop yield. We showed that agricultural simplification at the landscape scale is associated with an overall reduction in parasitism rates of crop pests. Additionally, only introduced parasitoids were identified, and no native parasitoids were found in crop habitat, irrespective of agricultural landscape simplification. Pest densities in the crop were lower in landscapes with greater proportions of semi-natural habitats. Furthermore, farms with less semi-natural cover in the landscape and consequently, higher pest numbers, had lower yields than farms in less agriculturally dominated landscapes. Our study demonstrates the importance of landscape scale agricultural simplification in mediating the success of biological control programs and highlights the potential risks to native natural enemies in classical biological control programs against native insects. Our results represent an important contribution to an understanding of the landscape-mediated impacts on crop yield that will be essential to implementing effective policies that simultaneously conserve biodiversity and ecosystem services.

How gut transcriptional function of Drosophila melanogaster varies with the presence and composition of the gut microbiota.

Despite evidence from laboratory experiments that perturbation of the gut microbiota affects many traits of the animal host, our understanding of the effect of variation in microbiota composition on animals in natural populations is very limited. The core purpose of this study on the fruit fly Drosophila melanogaster was to identify the impact of natural variation in the taxonomic composition of gut bacterial communities on host traits, with the gut transcriptome as a molecular index of microbiota-responsive host traits. Use of the gut transcriptome was validated by demonstrating significant transcriptional differences between the guts of laboratory flies colonized with bacteria and maintained under axenic conditions. Wild Drosophila from six field collections made over two years had gut bacterial communities of diverse composition, dominated to varying extents by Acetobacteraceae and Enterobacteriaceae. The gut transcriptomes also varied among collections and differed markedly from those of laboratory flies. However, no overall relationship between variation in the wild fly transcriptome and taxonomic composition of the gut microbiota was evident at all taxonomic scales of bacteria tested for both individual fly genes and functional categories in Gene Ontology. We conclude that the interaction between microbiota composition and host functional traits may be confounded by uncontrolled variation in both ecological circumstance and host traits (e.g., genotype, age physiological condition) under natural conditions, and that microbiota effects on host traits identified in the laboratory should, therefore, be extrapolated to field population with great caution.

Temporally dependent pollinator competition and facilitation with mass flowering crops affects yield in co-blooming crops.

One of the greatest challenges in sustainable agricultural production is managing ecosystem services, such as pollination, in ways that maximize crop yields. Most efforts to increase services by wild pollinators focus on management of natural habitats surrounding farms or non-crop habitats within farms. However, mass flowering crops create resource pulses that may be important determinants of pollinator dynamics. Mass bloom attracts pollinators and it is unclear how this affects the pollination and yields of other co-blooming crops. We investigated the effects of mass flowering apple on the pollinator community and yield of co-blooming strawberry on farms spanning a gradient in cover of apple orchards in the landscape. The effect of mass flowering apple on strawberry was dependent on the stage of apple bloom. During early and peak apple bloom, pollinator abundance and yield were reduced in landscapes with high cover of apple orchards. Following peak apple bloom, pollinator abundance was greater on farms with high apple cover and corresponded with increased yields on these farms. Spatial and temporal overlap between mass flowering and co-blooming crops alters the strength and direction of these dynamics and suggests that yields can be optimized by designing agricultural systems that avoid competition while maximizing facilitation.

Field Evaluation of an Oviposition Deterrent for Management of Spotted-Wing Drosophila, Drosophila suzukii, and Potential Nontarget Effects.

Spotted-wing drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae), is a polyphagous, invasive pest of small fruits. Current management relies heavily on chemical insecticides, and an effective oviposition deterrent could contribute to alternative management approaches that reduce the need for these chemical insecticides. A novel deployment method for repelling Drosophila suzukii, thereby reducing D. suzukii oviposition in fall-bearing red raspberry, was evaluated in the field. Infestations occurring within 4 d after deployment were significantly lower in 2-m-long plots (Rubus idaeus 'Caroline') treated with the repellent (20% 1-octen-3-ol in specialized pheromone and lure application technology [SPLAT]) compared to control plots (blank SPLAT). Repellent-treated plots had roughly 28.8 and 49.5% fewer offspring reared per gram of fruit than control plots in two experiments, respectively. Nontarget effects were also evaluated in 2-m plot experiments as well as 5- by 5-m plot experiments. There were no differences in the number of parasitic hymenoptera trapped on yellow sticky cards hung in repellent compared to control plots. While there were no differences in the number of visits to raspberry flowers observed by honey bees in repellent versus control plots, the number of visits by bumble bees was greater in repellent plots compared to control plots. Challenges regarding evaporation rates and potential uses for repellents in an integrated pest management program for the control of D. suzukii are discussed.

Comparison of three dispenser distribution patterns for pheromone mating disruption of Paralobesia viteana (Lepidoptera: Tortricidae) in vineyards.

Over two growing seasons, Isomate GBM-Plus tube-type dispensers releasing the major pheromone component of grape berry moth, Paralobesia viteana (Clemens) (Lepidoptera: Tortricidae), were evaluated in vineyards (Vitis spp.) in Michigan, New York, and Pennsylvania. Dispensers were deployed in three different density-arrangement treatments: 124 dispensers per ha, 494 dispensers per ha, and a combined treatment with 124 dispensers per ha in the vineyard interior and 988 dispensers per ha at the vineyard border, equivalent to an overall density of 494 dispensers per ha. Moth captures and cluster infestation levels were compared at the perimeter and interior of vineyards receiving these different pheromone treatments and in vineyards receiving no pheromone. Orientation of male moths to pheromone-baited traps positioned at the perimeter and interior of vineyards was reduced as a result of mating disruption treatments compared with the nontreated control. These findings were consistent over both years of the study. Disruption of male moth captures in traps varied from 93 to 100% in treated vineyards, with the 494 dispensers per ha application rates providing significantly higher level of disruption than the 124 dispensers per ha rate, but only in 2007. Measurements of percentage of cluster infestation indicated much higher infestation at perimeters than in the interior of the vineyards in all three regions, but in both sample positions there was no significant effect of dispenser density on cluster infestation levels in either year. The contrasting results of high disruption of moth orientation to traps in vineyards that also had low levels of crop protection from this pheromone treatment are discussed in the context of strategies to improve mating disruption of this tortricid pest.

Effect of insecticide regimens on biological control of the tarnished plant bug, Lygus lineolaris, by Peristenus spp. in New York State apple orchards.

To improve biological control of Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), the European parasitoid Peristenus digoneutis Loan (Hymenoptera: Braconidae) was introduced into the US in the 1980's and has become established in forage alfalfa, strawberries and apples. The objective of this study was to determine how four different insecticide management regimes affected parasitism of L. lineolaris by Peristenus spp. During the summers of 2005 and 2006, L. lineolaris nymphs were collected from New York State apple orchards using industry standard, reduced risk, and organically approved insecticides only. A 'no insecticide' (abandoned orchard) treatment was also included in 2006. Rates of parasitism of L. lineolaris nymphs were determined using a DNA-based laboratory technique. Results indicated that insecticide treatment had a significant effect on rates of parasitism of L. lineolaris by Peristenus spp. Compared to the industry standard treatment, rates of parasitism were higher in reduced risk orchards and lower in organic orchards. These results suggest that it is difficult to predict a priori the consequences of insecticide programs and point to the need to take into consideration the specific pests and beneficial organisms involved as well as the crop and the specific insecticides being applied.