Search

BACKGROUND: Invasive species threaten the productivity and stability of natural and managed ecosystems. Predicting the spread of invaders, which can aid in early mitigation efforts, is a major challenge, especially in the face of climate change. While ecological niche models are effective tools to assess habitat suitability for invaders, such models have rarely been created for invasive pest species with rapidly expanding ranges. Here, we leveraged a national monitoring effort from 543 sites over 3 years to assess factors mediating the occurrence and abundance of brown marmorated stink bug (BMSB, Halyomorpha halys), an invasive insect pest that has readily established throughout much of the United States. RESULTS: We used maximum entropy models to estimate the suitable habitat of BMSB under several climate scenarios, and generalized boosted models to assess environmental factors that regulated BMSB abundance. Our models captured BMSB distribution and abundance with high accuracy, and predicted a 70% increase in suitable habitat under future climate scenarios. However, environmental factors that mediated the geographical distribution of BMSB were different from those driving abundance. While BMSB occurrence was most affected by winter precipitation and proximity to populated areas, BMSB abundance was influenced most strongly by evapotranspiration and solar photoperiod. CONCLUSION: Our results suggest that linking models of establishment (occurrence) and population dynamics (abundance) offers a more effective way to forecast the spread and impact of BMSB and other invasive species than simply occurrence-based models, allowing for targeted mitigation efforts. Implications of distribution shifts under climate change are discussed. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. Published version

Drosophila suzukii Matsumura, spotted-wing drosophila, is a major pest of small fruits and cherries and often managed with conventional insecticides. Our previous work found that erythritol, a nonnutritive polyol, has insecticidal properties to D. suzukii. Two formulations of erythritol (1.5M), with 0.5M sucrose or 0.1M sucralose, are most effective at killing D. suzukii. In this study, we investigated the nontarget effects of these erythritol formulations on honey bee Apis mellifera Linnaeus larvae, a pupal parasitoid of D. suzukii, Pachycrepoideus vindemiae Rondani, and western yellow jacket, Vespula pensylvanica Saussure. We directly exposed honey bee larvae by adding a high dose (2 µl) to larval cells and found no significant mortality from either formulation compared to the water control. Pachycrepoideus vindemiae may encounter erythritol in field settings when host plants of D. suzukii are sprayed. The erythritol+sucralose formulation was more detrimental than erythritol+sucrose to P. vindemiae, however, this effect was greatly reduced within a 21-d period when a floral source was present. Since yellow jackets are a nuisance pest and were attracted to the erythritol formulations in recent field trials, we tested adult V. pensylvanica survival with continuous consumption of these formulations in the laboratory. We found no detectable detriment from either formulation, compared to the sucrose control. Overall, both erythritol formulations caused minimal nontarget effects on honey bee larvae, P. vindemiae parasitoids, and western yellow jackets.

The nonnutritive sugar, erythritol, has the potential to be a human-safe management tool for the small fruits and cherry pest, Drosophila suzukii, or spotted-wing drosophila. Feeding on erythritol decreases fly survival and oviposition by starving and creating an osmotic imbalance in the body. Recently, we demonstrated that erythritol combined with another nonnutritive sugar, sucralose, was fed upon more than erythritol alone and hastens D. suzukii mortality. This suggests that sucralose is a suitable nonnutritive phagostimulant alternative to sucrose. Although promising, the nutritional and physiological impacts of sucralose on D. suzukii are unknown. In this study, we investigated whether sucralose is metabolized or excreted by D. suzukii when fed various erythritol, sucrose, and sucralose formulations. We found that sucralose cannot be metabolized or converted into any nutritional substitutes or storage carbohydrates in D. suzukii. Instead, sucralose molecules were largely accumulated in the hemolymph and slowly excreted from the body, creating a significant osmotic imbalance in D. suzukii. To excrete unused sugars, flies will use their own body fluids to restore homeostasis, resulting in losing a substantial amount of body weight and becoming desiccated in the process. In summary, ingesting sucralose leads to starvation and hyperosmotic pressure in the body, causing a decrease in fitness. With confirmation of sucralose being non-metabolizable and phagostimulative to D. suzukii, the erythritol+sucralose formulation is a promising insecticide for growers to use.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) also known as spotted-wing drosophila (SWD), is a pest native to Southeast Asia. In the last few decades, the pest has expanded its range to affect all major European and American fruit production regions. SWD is a highly adaptive insect that is able to disperse, survive, and flourish under a range of environmental conditions. Infestation by SWD generates both direct and indirect economic impacts through yield losses, shorter shelf life of infested fruit, and increased production costs. Fresh markets, frozen berries, and fruit export programs have been impacted by the pest due to zero tolerance for fruit infestation. As SWD control programs rely heavily on insecticides, exceedance of maximum residue levels (MRLs) has also resulted in crop rejections. The economic impact of SWD has been particularly severe for organic operations, mainly due to the limited availability of effective insecticides. Integrated pest management (IPM) of SWD could significantly reduce chemical inputs but would require substantial changes to horticultural management practices. This review evaluates the most promising methods studied as part of an IPM strategy against SWD across the world. For each of the considered techniques, the effectiveness, impact, sustainability, and stage of development are discussed.

Simple Summary Spotted-wing drosophila, Drosophila suzukii, is an invasive pest of soft-skinned fruits. Adult female flies oviposit, or lay eggs, into fruits where the larvae develop, making infested fruit unmarketable. The flies rely on alternative hosts, both cultivated and wild, to survive and maintain populations throughout the year. Better understanding of how the flies migrate between different hosts could be beneficial to improving management of the pest in crops. This study demonstrates potential to discriminate larval host of adult flies by analysis of fatty acids carried from the larvae to the adult stage in the body using a machine learning algorithm as an alternative to linear discriminant methods. Our study shows that fatty acids in adult flies can be used to determine larval host and that the machine learning algorithm can perform the discriminant analysis without making any assumptions about the data. Abstract Drosophila suzukii is a severe economic invasive pest of soft-skinned fruit crops. Management typically requires killing gravid adult female flies with insecticides to prevent damage resulting from oviposition and larval development. Fruits from cultivated and uncultivated host plants are used by the flies for reproduction at different times of the year, and knowledge of D. suzukii seasonal host plant use and movement patterns could be better exploited to protect vulnerable crops. Rearing and various marking methodologies for tracking movement patterns of D. suzukii across different landscapes have been used to better understand host use and movement of the pest. In this study, we report on potential to determine larval host for adult D. suzukii using their fatty acid profile or signature, and to use larval diet as an internal marker for adult flies in release-recapture experiments. Fatty acids can pass efficiently through trophic levels unmodified, and insects are constrained in the ability to synthesize fatty acids and may acquire them through diet. In many holometabolous insects, lipids acquired in the larval stage carry over to the adult stage. We tested the ability of a machine learning algorithm to discriminate adult D. suzukii reared from susceptible small fruit crops (blueberry, strawberry, blackberry and raspberry) and laboratory diet based on the fatty acid profile of adult flies. We found that fatty acid components in adult flies were significantly different when flies were reared on different hosts, and the machine learning algorithm was highly successful in correctly classifying flies according to their larval host based on fatty acid profile.

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.

Lipids and carbohydrates have long been measured in organisms with various techniques. The microseparation and calorimetric method for quantifying lipids with a vanillin reagent, and glycogen and sugars with an anthrone reagent in mosquitoes described by Van Handel have been adapted widely for many insect species. Given the common use of this technique and variety of applications, a review is warranted. First, the procedure and adaptations are described, followed by other procedures available for quantifying energetic reserves. Next, practical logistics for running assays are discussed for new users. Previously, these assays have been reviewed for studying the sugar feeding behavior of biting flies and parasitoids. This review will survey a wider variety of applications from 85 papers with an emphasis on publications since 2004. For example, nutrient assays have been applied to establish the baseline energetic reserves of insects under various conditions, evaluating habitat manipulation programs, to better understand maternal allocation, overwintering and mating behavior, and flight energetics.

The brown marmorated stink bug, Halyomorpha halys (Stal), has become a well-known pest to growers and homeowners since its 1996 introduction to the United States. A classical biocontrol programme i...

The azalea lace bug (Stephanitis pyrioides Scott) (Hemiptera: Tingidae) is an invasive pest of rhododendrons and azaleas (Ericaceae: Rhododendron), which feeds on the underside of leaves causing chlorosis, reduced photosynthesis, and even plant death. While insecticides can control this pest, growers, landscape managers, and homeowners have requested softer alternatives. Augmentative release of predatory green lacewing Chrysoperla sp. (Neuroptera: Chrysopidae) eggs and larvae has reduced S. pyrioides, but large-scale implementation may not be practical nor cost-effective. Attracting naturally occurring Chrysopidae with plant volatiles may be an economical and convenient option. In this study, we tested whether volatile blends 1) attracted Chrysoperla sp., and 2) controlled S. pyrioides populations on Rhododendron spp. in farm or urban landscapes. Experimental plots contained different multicomponent lures placed aboveground next to infested plants. Adult Chrysoperla sp., other natural enemies, and S. pyrioides from egg to adult stages were monitored in both farm and urban landscapes for two summers. Overall, two out of three volatile blends consistently attracted Chrysoperla sp. to sticky traps near baited plants. Methyl salicylate + acetic acid + 2-phenylethanol (methyl salicylate blend) and acetophenone + acetic acid + 2-phenylethanol (acetophenone blend) captured more adult Chrysoperla sp. than control traps in farm landscapes. However, only the acetophenone blend was associated with a slight reduction of S. pyrioides. Additional research is needed to determine whether the phenology of the first generation of both species are synchronized for effective season biological control in the Pacific Northwest.

The azalea lace bug, Stephanitis pyrioides, is a serious pest of azaleas and rhododendrons which is often controlled by systemic insecticides. However, the efficacy of softer approaches such as biological control and water sprays against this pest on rhododendrons is unknown. Therefore, we tested the commercially available green lacewing predator, Chrysoperla rufilabris, and water sprays on lace bug infestation in one laboratory and four field trials. First, 2nd instar predator larvae were confirmed to consume lace bug nymphs and sometimes adults. Second, tapping predator larvae from hexcel units over dry leaves of potted rhododendrons and shaking loose eggs over wet leaves were reliable application methods. Third, predator larvae released onto potted rhododendrons lowered lace bug counts for two weeks. Fourth, after four bi-weekly applications, plants receiving egg cards or water-sprays had reduced lace bug counts and fewer damaged leaves than control plants. Fifth, landscape plants receiving the sequential combination of water spray followed by predator egg releases had 44 to 90% lower lace bug abundance and fewer damaged leaves than the control. After lace bugs were initially dislodged, hatching predators might have consumed hatching lace bugs. Index words: biological control, Chrysoperla rufilabris (Burmeister), mechanical control, rhododendron, Stephanitis pyrioides (Scott) Species used in this study: Azalea lace bug (Stephanitis pyrioides Scott), green lacewing (Chrysoperla rufilabris Burmeister), Rhododendron (Rhododendron spp.)

Drosophila suzukii is widely studied because of its status as a global pest of berries and soft fruits. Environmental conditions and access to food resources impact the physiology and fitness of D. suzukii; these factors could also affect dispersal. Flight mills are a convenient tool for measuring and comparing the flight performance of insects. In this study, two experiments examined the effects of diet and humidity on D. suzukii flight performance using custom-built flight mills, and a third experiment compared the energy reserves of D. suzukii flown or not flown on flight mills. Over all flight assays, the median flight distance and duration were 27.16 m and 2.37 min, respectively, and the mean flight velocity was 0.18 m/s. The maximum flight distance and duration by an individual were 1.75 km and 2.35 h, respectively. Drosophila suzukii provisioned with blossoms, fruits, or standard laboratory diets flew farther distances and longer durations than starved flies. While starvation was associated with reduced flight performance, there were no observed differences between diet types. It remains unclear whether D. suzukii consistently use lipids, glycogen, sugar, or another energy source for flight because tethered individuals may not have flown enough to deplete energy reserves. Humidity did not affect flight performance of D. suzukii within a ~ 2 h test period. These data indicate that most D. suzukii are likely to remain within limited area (e.g., within a field) but that some individuals can disperse long distances (field to field spread).

Marigolds (Tagetes erecta L.) suppress nematodes and are attractive companion plants, but their role in biological control is unknown. We evaluated how exposure to marigold blooms impacts the aphid parasitoid, Aphidius platensis Brethes. Female wasps previously exposed to marigold spent more time walking and parasitizing Myzus percisae Sulzer or Schizaphis graminum Rodani aphids, and subsequently had higher parasitism rates. Meanwhile, completely starved wasps spent more time stationary and marginally more time grooming. Time spent probing, emergence rate, and sex ratio were not affected. Wasp survival was best on honey, followed by marigold, and lowest on non-blooming marigolds. Nutrient reserves of wasps given honey, aphid-infested marigold, or marigold alone were compared to newly-emerged unfed wasps. Their resulting lipid, glycogen and sugar levels were similar, suggesting that these foods helped wasps maintain reserves similar to emergence levels. These results suggest that marigold may improve biological control of aphids by A. platensis.

Spotted-wing drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae), is an invasive pest of soft-skinned fruits across the globe. Effective monitoring is necessary to manage this pest, but suitable attractants are still being identified. In this study, we combined lures with fermenting liquid baits to improve D. suzukii trapping specificity and attractiveness. We also measured the efficiency and specificity of baits/lures during different times of the season; the reproductive status of females among baits/lures; and the effects of locations and crop type on these response variables. We developed a metric that combined mating status and fat content to determine differences in types of females attracted. Lures utilizing yeast and sugar-based volatiles trapped the most D. suzukii. The addition of a commercial lure to yeast and sugar-based lures increased catches in most locations, but was also the least specific to D. suzukii. Apple juice-based chemical lures tended to be most specific to D. suzukii, while lures comprised of a singular attractant tended to trap more D. suzukii with a higher reproductive potential than combinations of attractants. Trap catch and lure specificity was lower during fruit development than fruit ripening. While catch amounts varied by geographic location and crop type, attractants performed similarly relative to each other in each location and crop. Based on the metrics in this study, the yeast and sugar-based attractants were the most effective lures. However, further work is needed to improve early season monitoring, elucidate the effects of physiological status on bait attraction, and understand how abiotic factors influence bait attraction.

Drosophila suzukii, spotted-wing drosophila (SWD), is a fly pest of small fruits and cherries often managed by chemical insecticides, and finding a convenient, human-safe alternative is a challenge. Erythritol, a non-caloric sugar, is safe for humans and toxic to D. suzukii by causing an osmotic imbalance. Combining erythritol with sucrose as a phagostimulant can enhance fly mortality. However, sucrose is sticky when applied on plants and provides flies with nutritional carbohydrate if a non-lethal dose is ingested. Therefore, our objectives were to find a sucrose alternative, a non-caloric sugar that also has phagostimulative properties, where the formulation will enhance mortality, and reduce daily oviposition rates before females die. Through capillary no-choice and choice experiments, flies fed on 0.1 M sucralose (Sul) readily, and flies consumed more 1.5 M erythritol: 0.1 M sucralose (E:Sul) formulation than erythritol alone. In eleven different mortality assays, E:Sul induced mortality as did the 1.5 M erythritol: 0.5 M sucrose (E:S) formulation, while E:Sul was more successful than E:S when D. suzukii could also drink water to offset water loss. Sucralose (0.1 M) itself had modest insecticidal properties, but when combined with erythritol it increased the insecticidal effect. Both E:Sul and E:S formulations reduced oviposition when it was directly fed to D. suzukii in a cotton wick or applied on blueberry fruit. The latter suggests that the sugary coating on fruits has a deterrent effect. Given the potential of E:Sul, additional studies on the effect of sucralose on fly osmolar regulation, sugar metabolism, and field efficacy trials are underway to provide growers an efficacious tool.

An improved understanding of the biology of the invasive pest, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is critical for the development of effective management strategies. Trapping is one technique used for both detection and control; however, the efficacy of trapping can vary depending on the target insect's physiological state, its behavioural priorities and the type of attractant used in the trap. We conducted a series of caged trapping experiments and a greenhouse trapping experiment to investigate the effects of D. suzukii feeding status, age, mating status, ovipositional status and seasonal morph type on the capture rate of traps baited with fermentation odours. Starved flies were trapped at greater rates compared to fed flies; more virgin flies were trapped than mated flies; flies deprived of an oviposition substrate were trapped more frequently than flies given an oviposition substrate. It is still unclear whether age or seasonal morphology affect bait response. Lastly, a caged choice experiment investigated the relationship between female reproductive status and attraction to fermentation or fruit odours. Fermentation‐based traps captured female flies regardless of their reproductive status but, ripe fruit‐based traps were more attractive to flies with more than seven eggs. In summary, studies that use fermentation‐based traps should recognize that capture rates of D. suzukii will depend on the feeding, mating and oviposition experiences of the population; also, fruit‐based traps may better target gravid females.

Halyomorpha halys (Stål), the brown marmorated stink bug or BMSB, has become a major pest and nuisance since it arrived in the U.S. in 1996. This insect can feed on approximately 200 different plant species, many of which are important ornamental crops. BMSB's preference for fruits and the damage they cause is known, but it is not known how their presence on non-fruiting woody ornamentals can impact vegetative growth. The first study confined adult BMSB to branches of established stock block trees of five plant species for one month. Four measurements were taken to assess plant growth: branch length, leaf area, number of leaves, and dry weight. The second study confined adult BMSB on seedlings of eight plant species for one or two months. In this study, the same four measurements were taken as well as the change in trunk diameter. Overall, there were no significant differences in plant growth and only some marginal differences between branches or seedlings caged with BMSB versus no BMSB (control) after one or two months. Adults laid eggs on all plants species in both trials, and nymphs were observed to develop to the 2nd instar stage in the seedling trial on all the plant species except for maple. Confinement of BMSB on branches of well-established nursery plants or on newly planted seedlings had little or no impact on growth over a two month exposure. Index words: Halyomorpha halys, Hemiptera, ornamentals, seedling, vegetative growth. Species used in this study: Brown marmorated stink bug (Halyomorpha halys Stål); Dolgo crabapple (Malus sp.); Yoshino cherry (Prunus yedoensis Matsum.); Japanese elm (Ulmus davidiana Planch.); Siberian elm (Ulmus pumila L.); Ginkgo (Ginkgo biloba L.); Washington hawthorn (Crataegus phaenopyrum (L.f.) Medik); lsquo;Ivory Silk' lilac (Syringa reticulata Blume); ‘Green Mountain' silver linden (Tilia tomentosa Moench); ‘Crimson Sunset' maple (Acer truncatum Bunge); ‘Franksred' maple (Acer rubrum L.)

Biocontrol may play an important role in IPM of D. suzukii, a worldwide fruit crops pest. Predation on D. suzukii has been observed in the field, but rates have not been measured. Additionally, targeting juveniles may be more effective than targeting adults for reducing population sizes. The first objective of this study was to measure naturally-occurring levels of biocontrol on D. suzukii juveniles. Furthermore, D. suzukii may either pupate inside of fruit or emerge to pupate in the soil. Knowing the location of pupae can be important for developing biological and cultural control programs. The second objective of this study was to determine the proportion of D. suzukii pupating in fruit versus soil. Predator exclusion experiments were conducted to measure the ability of natural enemies to reduce D. suzukii larvae in strawberry and blueberry fruits, and pupae in the soil underneath strawberry, blueberry, and blackberry. Funnels were used to direct larvae dropping from infested blueberry and raspberry fruits into soil-filled containers. Significantly fewer D. suzukii larvae were extracted from fruits exposed to predators, representing a reduction in larval survival of 19–49%. Significantly fewer D. suzukii pupae were recovered from soil exposed to predators, representing a 61–91% decrease in pupae. In the pupation behavior experiment, 82–93% of pupae were found in soil, significantly more than were found in fruit. Ants and spiders were commonly observed in a variety of sampling methods, and ants were observed on video to remove pupae from the soil.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) and brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), are global economic pests that may co-occur on small fruits. We investigated whether fruit recently exposed to H. halys affected subsequent host use by D. suzukii. Laboratory no-choice and choice tests presented D. suzukii with H. halys-fed and unfed raspberries and blueberries immediately or 3 d after H. halys feeding. Resulting D. suzukii eggs, or larvae and pupae, were counted. The number of D. suzukii immatures among fed and unfed fruit was not significantly different in lab studies. There was no relationship between the intensity of H. halys feeding, as estimated by the number of stylet sheaths, and D. suzukii oviposition on blueberry. Lastly, field studies compared D. suzukii infestation between H. halys-fed and unfed raspberries. Raspberries were previously exposed to H. halys for 3 d or simultaneously exposed to both pests for 7 d. Natural infestation by D. suzukii in the field was similar among raspberries previously or simultaneously exposed to H. halys compared to control fruit.

In this study, we investigated the effects of non-nutritive sugars and sugar alcohols on the survivorship of spotted wing drosophila, Drosophila suzukii, and found erythritol and erythrose as potentially insecticidal to the fly. In a dose-dependent study, erythritol and erythrose significantly reduced fly longevity, with 100% mortality with 1, 0.5, 0.1 & 0.05M doses after feeding for 7days. When sucrose and erythritol solutions were provided separately to flies for 7days, there was no effect on survivorship regardless of erythritol concentrations. However, with a serial combination of sucrose and erythritol solutions, fly survivorship was significantly decreased for the same period. Also, the higher dose of erythritol regardless of the sucrose dose combined showed greater mortality. In a no-choice assay, D. suzukii ingested more erythritol than sucrose or water, indicating the fly continuously fed on erythritol for 72h. Also under no-choice conditions, erythritol and sucrose-fed flies gained more weight than water-fed flies. However, in two-choice assays, the amount of erythritol ingested was less than sucrose or water. Total sugar and glycogen levels among erythritol and erythrose-fed flies were significantly less than mannitol, sorbitol, xylitol, and sucrose-fed flies after 48h. This indicates that these two non-nutritive sugars can't be used a substrate for enzymes involved in sugar metabolism. Although the metabolism of erythritol and erythrose is unknown in insects, the mortality of D. suzukii flies ingesting these sugars might be caused by two potential physiological changes. The fly is starved by feeding of non-metabolizable erythritol and erythrose, or experiences abnormally high osmotic pressure in the hemolymph with erythritol molecules diffused from the midgut. Non-nutritive sugars might be used as an insecticide alone or combined with conventional or biological insecticides to enhance efficacy. If other sugar sources are present, a palatable sugar might be mixed with erythritol to elicit feeding.

Following the global invasion of Drosophila suzukii (spotted-wing drosophila or SWD), nearly 100 studies have explored biological control of this pest. In 2019, a review summarized 75+ papers covering 57 species of SWD parasitoids, predators, competitors, and pathogens and identified the most promising ones. This review provides an update with recent studies. Since parasitoids are promising natural enemies that can be host-specific and self-disperse, this chapter focuses on SWD parasitoids in its invaded and native ranges, and prospects for classical biological control. To date, six species have been confirmed to attack SWD in the invaded regions including three widely studied generalist pupal parasitoids, Pachycrepoideus vindemiae, Trichopria drosophilae, and T. anastrephae. No locally occurring larval drosophila parasitoids can develop from SWD. In contrast, foreign explorations in China, Japan, and South Korea have revealed 19 species of SWD larval parasitoids. Asobara japonica, Ganaspis brasiliensis, and Leptopilina japonica spp. japonica have been evaluated. Ganaspis brasiliensis is a complex of cryptic species/strains with varying host specificity, some which also occur in regions outside of Asia, but one East Asian strain was found to be the most host-specific to SWD and is currently being petitioned for introduction into North America and Europe.

After the introduction of an invasive species is confirmed in a new area, the next step in mitigation and management step is surveying to determine the range and extent of spread. Determining which monitoring methods are most effective and efficient is essential to determining range and spread, and research efforts at the onset of a biological invasive often focus on developing these technologies. This was certainly the case for Drosophila suzukii. A substantial amount of research in the early stages of the D. suzukii invasion into North America, and Europe focused on the design of monitoring traps and the identification of attractants. Later efforts shifting to interpreting monitoring data in the context of population estimation and crop risk. In this chapter, we review the current state of knowledge surrounding adult and larval D. suzukii monitoring methods, and how data generated using these methods can be applied to research and management questions.

Drosophila suzukii (Matsumura) is native to East Asia but has widely established in the Americas and Europe, where it is a devastating pest of soft-skinned fruits. It has a wide host range and these non-crop habitats harbor the fly which then repeatedly reinvades crop fields. Biological control in non-crop habitats could be the cornerstone for sustainable management at the landscape level. Toward this goal, researchers have developed or investigated biological control tactics. We review over 100 studies, conducted in the Americas, Asia and Europe on natural enemies of D. suzukii . Two previous reviews provided an overview of potential natural enemies and detailed accounts on foreign explorations. Here, we provide an up-to-date list of known or evaluated parasitoids, predators and entomopathogens (pathogenic fungi, bacteria, nematodes, and viruses) and summarize research progress to date. We emphasize a systematic approach toward the development of biological control strategies that can stand alone or be combined with more conventional control tools. Finally, we propose a framework for the integrated use of biological control tools, from classical biological control with host-specific Asian parasitoids, to augmentative and conservation biological control with indigenous natural enemies, to the use of entomopathogens. This review provides a roadmap to foster the use of biological control tools in more sustainable D. suzukii control programs.

Reliable monitoring of the invasive Halyomorpha halys abundance, phenology and geographic distribution is critical for its management. Halyomorpha halys adult and nymphal captures on clear sticky traps and in black pyramid traps were compared in 18 states across the Great Lakes, Mid-Atlantic, Southeast, Pacific Northwest and Western regions of the United States. Traps were baited with commercial lures containing the H. halys pheromone and synergist, and deployed at field sites bordering agricultural or urban locations with H. halys host plants. Nymphal and adult captures in pyramid traps were greater than those on sticky traps, but captures were positively correlated between the two trap types within each region and during the early-, mid- and late season across all sites. Sites were further classified as having a low, moderate or high relative H. halys density and again showed positive correlations between captures for the two trap types for nymphs and adults. Among regions, the greatest adult captures were recorded in the Southeast and Mid-Atlantic on pyramid and sticky traps, respectively, with lowest captures recorded in the West. Nymphal captures, while lower than adult captures, were greatest in the Southeast and lowest in the West. Nymphal and adult captures were, generally, greatest during July-August and September-October, respectively. Trapping data were compared with available phenological models showing comparable population peaks at most locations. Results demonstrated that sticky traps offer a simpler alternative to pyramid traps, but both can be reliable tools to monitor H. halys in different geographical locations with varying population densities throughout the season. USDA-NIFA-SCRI [2016-51181-25409] We are tremendously grateful for the excellent technical assistance provided by the numerous technicians and student research assistants involved in this study. This research was supported by USDA-NIFA-SCRI 2016-51181-25409. Mention of trade names or commercial products in this publication is solely for the purpose of providing scientific information and does not constitute recommendation or endorsement by the United States Department of Agriculture. USDA is an equal opportunity provider and employer. Public domain – authored by a U.S. government employee

Vinegar flies (Diptera: Drosophilidae) are well known to be associated with yeasts, which provide important nutrients and emit attractive semiochemicals. Drosophila suzukii (Matsumura) has become a major pest of berries and cherries around the world, requiring intensive management to maintain fruit quality. Although insecticides remain a dominant control approach, disruption of fly–yeast–host interactions remains a promising avenue for reducing the economic impact of this pest. We conducted field and laboratory experiments to explore whether a crop sterilant (peroxyacetic acid and hydrogen peroxide) developed for disease control can affect D. suzukii. In 2 yr of field tests in highbush blueberries, we found significantly lower infestation by D. suzukii in plots treated with the crop sterilant, both alone and in a rotation program with zeta-cypermethrin. When shoots from treated plots were tested in no-choice bioassays, crop sterilant treatments did not affect adult mortality or oviposition, but they reduced infestation. To explore the mechanisms in the laboratory, we found that the crop sterilant did not affect adult mortality, nor oviposition on treated fruit under no-choice settings, but adult flies settled and oviposited less on treated fruit in choice settings. When the crop sterilant was applied to colonies of Hanseniaspora uvarum (Niehaus) (Saccharomycetales: Saccharomycodaceae) and Issatchenkia terricola (Van der Walt) (Saccharomycetales: Saccharomycetacea) yeasts that are attractive and provide nutrition to D. suzukii, there was a dose-dependent inhibition of their growth. We highlight the potential for microbial management as a component of integrated pest management programs and prioritize research needs to incorporate this approach into control programs.

Since the arrival of Drosophila suzukii M. (Diptera: Drosophilidae), field applications of broad-spectrum insecticides have increased in berry crop production to protect susceptible fruits from infestation. Field studies were conducted from 2011 to 2013 to determine whether alternate row middle or border spray programs could manage D. suzukii as well as complete sprays and have less of an impact on non-target arthropods. Four raspberry sites and one blueberry site were alternate row middle and border sprayed, respectively. Adult and larva counts of D. suzukii were compared to conventional complete spray programs. Non-target arthropods were evaluated 7 d post-harvest. In both reduced spray trials, no differences in mean adult numbers and larvae of D. suzukii were detected between treatments. Mean counts immediately after sprays (i.e. 3–12 d after treatment) were also similar in complete and alternate row sprays. Both reduced spray strategies had significantly more Stethorus spp.; additionally, alternate row sprays had significantly more Psyllobora spp. These reduced pesticide strategies are additional tools to consider in D. suzukii IPM programs that can reduce the area sprayed, application time, and input costs while conserving natural enemies.

Knowledge regarding the reproductive status of spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is of critical importance in predicting potential infestations of this invasive pest, as eggs are laid in ripe or ripening fruit of several commercially important small-fruit crops. Token environmental stimuli for the induction of reproductive diapause and improved cold tolerance were identified for D. suzukii. Diapause induction was evaluated by assessing, via dissection, the number of mature eggs carried by field-captured D. suzukii and laboratory-reared D. suzukii held under various temperature and photoperiod regimes. Egg load decreased over time in females trapped from July to December at sites in Benton County, OR, and Ontario County, NY, both USA, and reached zero eggs by December at all sites. Photoperiods below 14 h of day length led to reduced egg maturation in laboratory-reared flies held at moderate temperatures (15 or 20 °C). Whereas very few mature eggs were found in females held at 10 °C under short- or long-day photoperiods for several weeks after eclosion, a spontaneous return to ovarian maturity was observed in short-day-entrained females after 7 weeks. Diapause termination was investigated by evaluating fecundity in diapausing females returned to optimal environmental conditions. Whereas long-day-entrained flies began producing offspring immediately upon return to optimal conditions, short-day-entrained flies returned after 1 and 6 weeks at 10 °C were slower to produce offspring than colony flies or short-day-entrained flies returned after 7 weeks. Cold tolerance was evaluated by observing chill coma recovery rates after 24 h exposure to −1 °C. Cold-acclimated (diapausing) females recovered from chill coma faster than cold-hardened or unacclimated females.

Drosophila suzukii, spotted wing drosophila, is a serious pest of small fruits and cherries in many regions of the world. While host usage has been well studied at the ovipositional and larval feeding stages, little is known about the feeding ecology and nutrient requirements of adults. This study addressed the impact of feeding on the survival and nutrient reserves of adult D. suzukii in laboratory assays. First, access to cherry blossoms increased survival rates of both adult males and females compared to water only. This suggests that these early spring blossoms may provide a food source for D. suzukii in fields that may be devoid of other food sources. Second, D. suzukii reared on a standard laboratory diet as larvae emerged as adults with minimal glycogen and sugar levels. Adults with continued access to a carbohydrate–protein diet showed rapidly elevated carbohydrate reserves, and adults with continued access to only water showed a decline in total sugars. Third, females with access to cherry or blueberry blossoms showed elevated carbohydrate reserves when compared to those with access to water only. These results illustrate the importance of adult feeding in enhancing survival and carbohydrate reserves among D. suzukii.

Spotted wing drosophila, Drosophila suzukii, is a devastating invasive pest of small and stone fruits in the Americas and Europe. To better understand the population dynamics of D. suzukii, we reviewed recent work on juvenile development, adult reproduction, and seasonal variation in life history parameters including the abiotic/biotic factors that influence these processes. Juvenile development is optimal at moderately warm temperatures, and larvae exhibit some immunity to parasitism. Adults use visual cues and substrate-borne vibrations for courtship and exhibit a bimodal locomotor activity pattern (except mated females). Under 20–27 °C and various conditions, development from egg to adult can take 10–17 days, females first lay eggs within 1–8 days and their lifetime fecundity varies from 400. Oviposition is consistently high in raspberry hosts and fruits with lower penetration force, and the presence of Wolbachia endosymbionts can lower fertility. Drosophila suzukii exhibit seasonal variation with a darker winter morph that is more cold tolerant. Also, D. suzukii likely undergo reproductive diapause in the fall, with colder temperatures and shorter day lengths influencing reproduction. To develop viable IPM programs for D. suzukii, knowledge of abiotic and biotic conditions that impact D. suzukii life history parameters and population dynamics is critical, and gaps in the current knowledge are discussed.

Spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is originally from Asia, and in the last decade it has become a global economic pest of small fruits and cherries. Growers have expressed strong interest in biological control and other sustainable tactics to reduce reliance on insecticides. Biological control of spotted-wing drosophila has been studied intensively, with over 75 research publications. Here, we are reporting current information on predators, parasitoids, pathogens (fungi, nematodes, bacteria, endosymbiotic bacteria, and viruses), and competitors of spotted-wing drosophila. When relevant for the natural enemy group, the discussion focuses on the impact each natural enemy has been observed to have in the field, how to optimize control, the efficacy of commercial products available, and options that may be available in the near future. Studies are summarized in tables that can be sorted by species, spotted-wing drosophila life stage targeted, outcomes, lab/field trials, and studies that examined residual activity, dose-dependent responses, or other effects.

Life history parameters are used to estimate population dynamics, mortality, and reproduction in insects relative to their surrounding environment. For Drosophila suzukii Matsumura (Diptera: Drosophilidae), an invasive agricultural pest, previous studies have estimated net reproductive rate (Ro), generation time (T), and intrinsic rate of population increase (rm). A main limitation is that these estimates were measured under relatively favorable settings, and do not reflect environmental conditions and physiological states encountered during dormancy periods. Therefore, this study investigated the impacts of 1) low temperatures and 2) dietary protein: carbohydrate ratios (P:C) on both survival and fecundity parameters of D. suzukii summer morphs (SM) and postoverwintering winter morphs (WM) over physiological age (degree-days, DD). In both morphs, reproductive rates were higher and lifespan was longer when flies were exposed to low protein (P:C 1:4) or carbohydrate-only diets (P:C 0:1) compared with high protein diets (P:C 1:1). WM had higher reproductive rates and longer generation times than SM on optimal 1:4 diet in all trialed temperatures, but at the lowest temperatures, SM had higher reproductive rates than WM in carbohydrate-only and high protein diets. This likely reflected delayed oogenesis and hindered reproduction after an overwintering period in WM receiving suboptimal diets. Oviposition for SM and WM receiving 1:4 diet commenced from 0 to 100 DD, and peaked between 400 and 500 DD, earlier than flies receiving 0:1 diet. These results suggest that dietary protein has a crucial role in early oogenesis, particularly for postoverwintering WM. The parameters developed here reflect the population dynamics of D. suzukii before and after the crop growing season, an essential time for population buildup, survival, and early and late host infestation.

Halyomorpha halys (St&aring, l), or brown marmorated stink bug (BMSB), has become a major pest and nuisance for both agricultural growers and homeowners since its arrival in North America and Europe. The nutritional ecology of BMSB is important for understanding its life history and rearing requirements. However, little is known about the nutritional status of wild populations, especially in the U.S. This research monitored the nutrient status of nymphal and adult BMSB collected from English holly in western Oregon. We measured their weight, nutrient index (weight/(prothorax &times, width)3), lipid, glycogen and sugar levels and egg load from May&ndash, September/October. First, glycogen and sugar levels of adults were often lowest sometime in June-August with a general increase by September. Meanwhile, their lipid levels varied without a discernible trend. Second, adult females had few eggs in May, with the highest egg load in June and July, and no eggs by September. Lastly, first and second nymphal instars were found in June, and fourth and fifth instars in September. Because nothing is known about the nutrient levels of nymphs, the reported values from this survey can assist future research on physiological responses of BMSB to treatments or environmental impacts in the field.

Previous studies have demonstrated various combinations of non-nutritive erythritol and sucrose having detrimental effects on Drosophila suzukii (Matsumura). Fly mortality is likely caused by 1) starvation from feeding on non-metabolizable erythritol; and 2) physiological imbalance with abnormally high osmotic pressure in the hemolymph. While erythritol kills D. suzukii in controlled environments, flies in the field can access naturally-occurring sugar sources. We evaluated fly mortality in the presence or absence of wounded fruits, and an erythritol mixture of 2.0 M erythritol:0.5 M sucrose (E+S), or erythritol- and sucrose-only controls. When provided E+S, survival was consistently lower than sucrose controls with/out wounded fruit, suggesting that this mixture still has a detrimental effect in the presence of competing sugar sources. Our second study examined the effects of diet on fecundity and egg load of female D. suzukii. Females laid fewer eggs on blueberries when fed E+S or erythritol-only than sucrose. Unexpectedly, females fed E+S had more ovarial eggs than sucrose-fed females, suggesting that erythritol might inhibit D. suzukii laying eggs. Lastly, we evaluated honey bee survivorship by enclosing bees with one of four diets in a cage. The erythritol mixture had no discernible impact on adult survivorship during 7 d.

Viruses vectored by the aphid Amphorophora agathonica cause decline in black raspberry plant health resulting in a shortened life and poor fruit quality of the infected plantings. New aphid resistant cultivars could increase the longevity of plantings providing growers and processors with consistent fruit production. Recent exploration of the native range of black raspberry identified three sources of aphid resistance: Ag4 from Ontario (ON), Canada, Ag5 from Maine (ME), and a third source from Michigan (MI) with no formal designation. The objectives of this study were to assess segregation of these three sources of aphid resistance in populations with single and combined sources and develop markers that can identify each source of resistance. A genetic linkage map constructed for ORUS 4305 placed the ON aphid resistance locus on Rubus linkage group (RLG) 6. Segregation ratios in populations with single and combined sources, and linkage mapping in two populations (ORUS 4304 and ORUS 4812) segregating for the Ag5 and MI sources, respectively, indicated that these three sources of resistance are each conferred by single dominant genes/alleles that are linked on RLG6. Confirmation of marker association in 16 validation populations identified four markers that could be used to predict resistance; however, none could distinguish between the ON and MI sources. These four markers may be useful for screening populations to enrich the field-planted progeny for aphid resistance. Fine mapping of the resistance loci is needed to develop functional markers at each of the resistance loci to enable pyramiding and durable aphid resistance.

Drosophila suzukii (Matsumura) is an economic pest of small fruits and cherries that attacks intact ripening fruits. Host susceptibility may be influenced by characteristics such as flesh firmness, penetration force of the skin, total soluble solids (TSS, also known as °Brix), and pH. Improved knowledge of factors affecting fruit susceptibility is needed for developing thresholds and risk prediction models for IPM. A combination of laboratory and field studies was conducted to develop prediction and potential management tools. First, a direct bioassay was used to calculate the probability of oviposition in a given fruit based on various characteristics as determined across laboratory and field trials in Oregon and North Carolina, US. When multiple characteristics were evaluated simultaneously, oviposition probability consistently increased as penetration force decreased and pH increased. Oviposition probability sometimes increased as TSS increased. Second, raspberries and blueberries in unsprayed fields had substantially lower infestation in ripening fruit compared to ripe fruit. There was no or minimal infestation in green fruit. Third, given that skin penetration force influences oviposition, practices used to improve fruit quality were examined in laboratory no-choice cages for potential reduction of oviposition. Blueberry fruit sprayed with calcium silicate in the field had greater penetration force and firmness and reduced number of eggs laid by D. suzukii compared to untreated fruit. Other calcium-based treatments increased Ca content and firmness of fruit relative to untreated fruit. Timing of insecticide spray for D. suzukii might be delayed until fruit become susceptible.

Host plant resistance is a practical and cost-effective approach for growers to manage insect pests. Recently, three new sources of resistance in black raspberry (Rubus occidentalis; selections ORUS 3778-1, ORUS 3817-1, and ORUS 4109-1) against the large raspberry aphid, Amphorophora agathonica, were identified. We studied stages of host plant acceptance: host plant attraction, parturition (deposition of nymphs), nymph survival, and adult feeding behavior (using the electrical penetration graph [EPG]) to identify the location of the plant resistance. Aphids were more attracted to the susceptible cultivar ‘Munger’ (control) than the resistant selections. Parturition occurred on the resistant selections, but fewer nymphs were deposited on resistant lines relative to the susceptible control. Nymphs survived only an average of 3.3–3.6 days on resistant selections, whereas 94 % were still alive after 11 days on ‘Munger.’ There were differences in feeding behavior between the susceptible control and the resistant selections, but no differences between the three resistant selections. The tissues responsible for resistance appear to be the mesophyll and phloem sieve elements. Aphids had a reduced probability of salivation into the phloem sieve elements of resistant selections, and only one aphid each on ORUS 3778-1 and ORUS 4109-1 successfully ingested from the phloem. Because feeding behavior of A. agathonica did not differ between resistant selections, independent confirmation that resistance is conferred by unique genes should be obtained before pyramiding these sources together.

Temperature and humidity affect insect physiology, survival, fecundity, reproductive status and behaviour. Complementing previous work investigating the effects of temperature on adult survival and fecundity of the invasive frugivorous pest, Drosophila suzukii (Matsumura), this study was conducted to determine the effect of humidity on D. suzukii larval development, adult survival, fecundity and reproductive status using blueberry as a host substrate. The five constant humidity levels in laboratory bioassays were 20, 33, 71, 82 and 94% RH at 20.6 0.2°C. As RH increased, fecundity and longevity increased. At the higher humidity levels, RH had limited impact on mean generation times (T), larval development and eclosion times. The highest net reproductive rate (Ro = 68) and highest intrinsic rate of population increase (rm = 0.17) were both recorded at 94% RH. The reproductive status of females, as indicated by the number of mature oocytes per female, was significantly greater at 82 and 94% RH, compared to 71% RH. In addition to the laboratory procedures, we correlated field trap captures over an 81-day summer period to relative humidity (RH) levels in close proximity to those traps. In the field, low ambient humidity levels resulted in decreased trap captures. A humidity-dependent population model predicted lower densities of D. suzukii relative to populations at higher humidity. This study supports the hypothesis that cultural practices that minimize lower humidity levels in crops can contribute to the management of D. suzukii. Such methods may include open pruning, drip irrigation and field floor management.

Spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), may utilize wild ‘Himalaya’ blackberry (HB) Rubus armeniacus Focke or other non-crop plants as refugia and possibly exploit adjacent field margins before colonizing cultivated fruiting crops. Studies were conducted to determine the role of field margins containing HB and their effect on D. suzukii activity, density and distribution in an adjacent commercial red raspberry crop. One-ha plots adjacent to field margins containing HB or known non-host (NH) grass crops were established in 2011 and 2012 and replicated three times. Each plot contained two transects with monitoring traps for D. suzukii in the field margin (0 m) and spaced approximately 10 (crop boundary), 40, 70 and 100 m into the adjacent crop (n = 10 traps/plot). Field margin vegetation was treated with a 10% chicken egg white mark solution weekly from pre-harvest until the end of harvest using a cannon sprayer. Adult D. suzukii were collected from traps weekly and analysed for the presence of the egg white mark using an egg white-specific enzyme-linked immunosorbent assay (ELISA). During both years, marked flies and total flies were captured in higher numbers in HB field margins, whereas virtually no flies were captured in field margins containing no known alternative host. Similarly, more flies were captured in the crop near HB than near NH. Spatial Analysis by Distance IndicEs (SADIE) and mean D. suzukii trap captures additionally displayed significantly higher fly densities in the raspberry field near HB than near NH. These results suggest that HB may contribute to elevated D. suzukii populations and pest pressure in comparison with field margins containing no known alternate host vegetation for D. suzukii. Having closely adjacent non-crop alternate host landscapes may result in increased D. suzukii pest pressure.