Effects of nonnutritional sugars on lipid and carbohydrate content, physiological uptake, and excretion in Drosophila suzukii.

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.

Attracting Chrysopidae With Plant Volatiles for Lace Bug (Hemiptera: Tingidae) Control in Rhododendrons and Azaleas.

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.

Survival and Fecundity Parameters of Two Drosophila suzukii (Diptera: Drosophilidae) Morphs on Variable Diet Under Suboptimal Temperatures.

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.

Flourishing with sugars - following the fate of parasitoids in the field.

When flowers, plants bearing extrafloral nectaries, or sugar sprays are added to agroecosystems, parasitoids are expected to feed, thereby improving biological control. This paper reviews studies where sugar-feeding of field-collected parasitoids were monitored via biochemical assays. When examined, trends in parasitoid abundance, energetic reserves, longevity, and per capita fecundity are also followed. Starved parasitoids readily feed on sugar sources in the field, and more individuals collected near sugar sources are categorized as 'fed' when sugar is otherwise limited in the agroecosystem. When sugar is not limited (i.e. honeydew prevalent), trends are not as clear. Some studies show improved fecundity and parasitism, while other studies show inconsistent trends between parasitoid feeding, abundance, longevity, and parasitism, with some responses improved but not others. Future research could address the dispersal or resting behavior of wasps following feeding since it can influence eventual biological control, and consider whether field sampling methods might over-/underestimate feeding.

An Effective Fluorescent Marker for Tracking the Dispersal of Small Insects with Field Evidence of Mark-Release-Recapture of Trissolcus japonicus.

Understanding insect dispersal helps us predict the spread of insect pests and their natural enemies. Dispersal can be studied by marking, releasing, and recapturing insects, known as mark-release-recapture (MRR). MRR techniques should be convenient, economical, and persistent. Currently, there are limited options for marking small parasitoids that do not impact their fitness and dispersal ability. We evaluated commercially available fluorescent markers used in forensics. These fluorophores can easily be detected by ultraviolet (UV) light, requiring minimal costs and labor to process the marked specimens. This fluorophore marking technique was evaluated with the pest Drosophila suzukii and three parasitoids: Trissolcus japonicus, Pachycrepoideus vindemiae, Ganaspis brasiliensis (=G. kimorum). We evaluated the persistence of the marks on all the insects over time and examined the parasitoids for impacts on longevity, parasitism, locomotor activity, and flight take-off. The green fluorophore marker persisted for over 20 days on all four species. Marking generally did not consistently reduce the survival, parasitism rate, locomotor activity, or take-off of the parasitoids tested. Marked T. japonicus were recaptured in the field up to 100 m away from the release point and three weeks after release, indicating that this technique is a viable method for studying parasitoid dispersal.

Silicon supplementation can reduce infestation by azalea lace bug-(Hemiptera: Tingidae).

The azalea lace bug (ALB), Stephanitis pyrioides (Scott) (Hemiptera: Tingidae), is a pest of azaleas and rhododendrons. The application of silicon (Si) to plants has been shown to accumulate in other plants and enhance defense to other plant pests. We evaluated whether Si applications decreased ALB infestation on rhododendron leaves and increased Si accumulation in leaves. Potted plants were treated with 4 or 8 weekly applications of calcium silicate and calcium carbonate (calcium control, Ca) via foliar or soil application. In 3 out of 4 choice studies, plants treated with calcium silicate or calcium carbonate had less frass deposition and oviposition by ALB compared to controls, but treated plants did not consistently have fewer ALB adults. Leaf damage was quantified in one study and leaves with more frass as an indicator of feeding had more visible damage. In no-choice studies, there were no differences between treatments in one study, but oviposition was greater on foliar/soil Si-treated plants than controls in another study. Since rhododendron aphids (Illinoia lambersi) appeared in the greenhouse during or after studies, we compared their colonization on previously treated rhododendrons. Infestation of new leaf rosettes or random leaves by I. lambersi was lower on plants sprayed with foliar silicon or calcium applied via soil in 2 studies. Treated rhododendrons did not accumulate extra Si or Ca in leaves compared to controls. In general, silicon or calcium application protected rhododendrons from ALB oviposition and aphid colonization in free-choice conditions, and may be part of an integrated pest management program.

Compatibility of Entomopathogenic Nematodes with Chemical Insecticides for the Control of Drosophila suzukii (Diptera: Drosophilidae).

The spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is a pest that reduces the productivity of small fruits. Entomopathogenic nematodes (EPNs) and chemical insecticides can suppress this pest, but the compatibility of the two approaches together requires further examination. This laboratory study evaluated the compatibility of Steinernema brazilense IBCBn 06, S. carpocapsae IBCBn 02, Heterorhabditis amazonensis IBCBn 24, and H. bacteriophora HB with ten chemical insecticides registered for managing D. suzukii pupae. In the first study, most insecticides at the recommended rate did not reduce the viability (% of living infective juveniles (IJs)) of S. braziliense and both Heterorhabditis species. The viability of S. carpocapsae was lowered by exposure to spinetoram, malathion, abamectin, azadirachtin, deltamethrin, lambda-cyhalothrin, malathion, and spinetoram after 48 h. During infectivity bioassays, phosmet was compatible with all the EPNs, causing minimal changes in infectivity (% pupal mortality) and efficiency relative to EPN-only controls, whereas lambda-cyhalothrin generally reduced infectivity of EPNs on D. suzukii pupae the most, with a 53, 75, 57, and 13% reduction in infectivity efficiency among H. bacteriophora, H. amazonensis, S. carpocapsae, and S. brazilense, respectively. The second study compared pupal mortality caused by the two most compatible nematode species and five insecticides in various combinations. Both Heterorhabditis species caused 78-79% mortality among D. suzukii pupae when used alone, and were tested in combination with spinetoram, malathion, azadirachtin, phosmet, or novaluron at a one-quarter rate. Notably, H. bacteriophora caused 79% mortality on D. suzukii pupae when used alone, and 89% mortality when combined with spinetoram, showing an additive effect. Novaluron drastically reduced the number of progeny IJs when combined with H. amazonensis by 270 IJs and H. bacteriophora by 218. Any adult flies that emerged from EPN-insecticide-treated pupae had a shorter lifespan than from untreated pupae. The combined use of Heterorhabditis and compatible chemical insecticides was promising, except for novaluron.

Susceptibility of cranberries to Drosophila suzukii (Diptera: Drosophilidae).

Drosophila suzukii Matsumura (Diptera: Drosophilidae), commonly referred to as the spotted wing drosophila, is an exotic species that has proven a troublesome pest of fruit production in the United States. The fly targets small fruit and thus represents a concern for the U.S. cranberry industry. Two studies were conducted to assess whether cranberries may serve as hosts for D. suzukii. In the first study, the suitability of ripe, unripe, and over-ripe cranberries were assayed by examining adult oviposition and larval development in no-choice trials. In the second study, wounded and unwounded fruit were examined as potential hosts in choice and no-choice trials. Our first study showed that ripe, unripe, and over-ripe cranberries were unsuitable hosts (few eggs were laid, with no surviving puparia). In the wounded and unwounded berry study, no larvae survived to adulthood among unwounded berries. Within wounded fruit, D. suzukii readily fed and developed into adults. Together, these results suggest that unwounded cranberries--whether ripe, unripe, or over-ripe--are unsuitable as hosts for D. suzukii. Wounded rotting cranberries, however, can serve as hosts. Across the landscape, cranberry marshes with rotting fruit may contribute to D. suzukii source-sink dynamics.

Erythritol sprays reduce Drosophila suzukii infestation without impacting honey bee visitation nor fruit quality.

BACKGROUND: Spotted-wing drosophila, Drosophila suzukii, is an economic pest of small fruits and cherries. Insecticides primarily control this pest while alternative controls are in development. Laboratory studies show that erythritol is insecticidal to D. suzukii and other pests while approved for human consumption. Moreover, erythritol combined with sucrose or non-caloric sucralose can stimulate feeding and quicken mortality. Before growers can use erythritol, the impact on crop protection, non-target insects, and fruit quality need evaluation. RESULTS: In three blueberry and cherry field cage trials, oviposition on fruit sprayed with erythritol:sucrose or erythritol:sucralose formulations was lowered by 59%-81% compared with unsprayed controls. Fly infestation (larval or adult counts from fruit) was 90% lower in a greenhouse blueberry trial, and 49% lower in an open field blueberry trial with 2 m erythritol : 0.5 m sucrose. Infestation was also 57% lower in an open field cherry trial with 1.5 m erythritol:0.5 m sucrose. Other field trials with very low pest pressure or frequent rains revealed no differences from controls. Field trials consistently revealed that honey bees did not preferentially visit plants sprayed with either erythritol formulation, although yellow jackets visited plants sprayed with erythritol:sucrose more frequently. Erythritol formulations consistently led to more leaf spotting, but there was no reduction in the quality of treated blueberries or cherries in terms of mold development, firmness, diameter, epidermal penetration force, and Brix° (total soluble solids) at harvest. CONCLUSION: Eleven trials conducted over four years show that erythritol formulations can reduce D. suzukii pressure without attracting foraging honey bees nor negatively impacting fruit quality. © 2023 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Insecticidal Properties of Erythritol on Four Tropical Tephritid Fruit Flies, Zeugodacus cucurbitae, Ceratitis capitata, Bactrocera dorsalis, and B. latifrons (Diptera: Tephritidae).

Tephritid fruit flies are among the most destructive agricultural pests of fruits and vegetables worldwide and can impose trade barriers against the movement of fresh tropical commodities. Primary pre-harvest control methods for these flies rely on the spraying of conventional chemical insecticides or bait sprays. However, resistance to these control methods has been reported in fruit flies. Erythritol is a non-nutritive sugar alternative for human consumption, which has been tested and confirmed for its insecticidal properties against various insect pest species. In this study, using laboratory bioassays, we evaluated the insecticidal effect of erythritol alone or various erythritol formulations containing sucrose and/or protein on four tropical fruit fly species established in Hawaii (e.g., melon fly, Mediterranean fruit fly, oriental fruit fly, and Malaysian fruit fly). In addition, the effects of other non-nutritive hexose and pentose sugar alcohols, such as sorbitol, mannitol, and xylitol, were tested. Among the different standalone and combinatory treatments tested, 1M erythritol and a combinatory formulation of 2M erythritol + 0.5M sucrose appeared to be the most detrimental to the survival of all four species of tested flies, suggesting the potential of using erythritol as a non-toxic management tool for the control of tropical tephritid fruit flies.

Nonnutritive Sugars for Spotted-Wing Drosophila (Diptera: Drosophilidae) Control Have Minimal Nontarget Effects on Honey Bee Larvae, a Pupal Parasitoid, and Yellow Jackets.

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.

Transmission biology of Raspberry latent virus, the first aphid-borne reovirus.

Raspberry latent virus (RpLV) is a newly characterized reovirus found in commercial raspberry fields in the Pacific Northwest (PNW). Thus far, all members of the plant reoviruses are transmitted in a replicative, persistent manner by several species of leafhoppers or planthoppers. After several failed attempts to transmit RpLV using leafhoppers, the large raspberry aphid, commonly found in the PNW, was tested as a vector of the virus. The virus was transmitted to new, healthy raspberry plants when inoculated with groups of at least 50 viruliferous aphids, suggesting that aphids are vectors of RpLV, albeit inefficient ones. Using absolute and relative quantification methods, it was shown that the virus titer in aphids continued to increase after the acquisition period even when aphids were serially transferred onto fresh, healthy plants on a daily basis. Transmission experiments determined that RpLV has a 6-day latent period in the aphid before it becomes transmissible; however, it was not transmitted transovarially to the next generation. To our knowledge, this is the first report of a plant reovirus transmitted by an aphid. Phylogenetic analyses showed that RpLV is related most closely to but distinct from Rice ragged stunt virus (RRSV), the type member of the genus Oryzavirus. Moreover, the conserved nucleotide termini of the genomic segments of RpLV did not match those of RRSV or other plant reoviruses, allowing us to suggest that RpLV is probably the type member of a new genus in the Reoviridae comprising aphid-transmitted reoviruses.

Evaluation of monitoring traps for Drosophila suzukii (Diptera: Drosophilidae) in North America.

Drosophila suzukii Matsumura (Diptera: Drosophilidae), a recent invasive pest of small and stone fruits, has been detected in more than half of the U.S. states, and in Canada, Mexico, and Europe. Upon discovery, several different trap designs were recommended for monitoring. This study compared the trap designs across seven states/provinces in North America and nine crop types. Between May and November 2011, we compared a clear cup with 10 side holes (clear); a commercial trap with two side holes (commercial); a Rubbermaid container with mesh lid and rain tent (Haviland), and with 10 side holes and no tent (modified Haviland); a red cup with 10 side holes (red); and a white container with mesh lid and rain tent (Van Steenwyk). Although fly catches among traps varied per site, overall, the Haviland trap caught the most D. suzukii, followed by the red, Van Steenwyk, and clear trap. The modified Haviland and commercial trap had low captures. Among five crop types in Oregon, a clear cup with mesh sides (Dreves) also was tested and caught the most flies. Traps with greater entry areas, found in mesh traps, caught more flies than traps with smaller entry areas. In terms of sensitivity and selectivity, traps that caught more flies likewise caught flies earlier, and all traps caught 26-31% D. suzukii out of the total Drosophila captured. Future trap improvements should incorporate more entry points and focus on selective baits to improve efficiency and selectivity with regard to the seasonal behavior of D. suzukii.

Efficacy and Tolerability of HydraFacial Clarifying Treatment Series in the Treatment of Active Acne Vulgaris.

Objective: This 12-week, multicenter, open-label study investigated the efficacy and tolerability of the HydraFacial Clarifying Treatment for improving skin appearance in patients who present with acne vulgaris. Methods: Twenty eligible adult patients with mild-to-moderate acne were enrolled at one of two treatment sites in the United States and were to undergo six HydraFacial Clarifying Treatments, one every two weeks for 12 weeks. Treatment occurs in three steps: cleansing and peeling; suction to extract dead skin cells, sebum, and debris; and application of blue LED light. Acne severity was graded by investigators and by patients using the Global Acne Severity Score (GASS). Results: The proportion of patients with no acne or almost clear skin (GASS ≤1) at baseline versus final treatment increased from 20 to 65 percent per investigator assessment (p=0.0027), and from 5 to 55 percent per patient self-report (p=0.0016). At final treatment, more than 80 to 100 percent of both investigators and patients agreed or strongly agreed there was an improvement in skin appearance across multiple assessment parameters. Treatments were generally well tolerated. Limitations: Due to the nature of the treatment, blinding of neither investigators nor patients was feasible. Conclusion: The results presented here suggest that a series of six HydraFacial Clarifying Treatments improves overall skin appearance in patients with active acne.

A Coordinated Sampling and Identification Methodology for Larval Parasitoids of Spotted-Wing Drosophila.

We provide recommendations for sampling and identification of introduced larval parasitoids of spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). These parasitoids are either under consideration for importation (aka classical) biological control introductions, or their adventive (presumed to have been accidentally introduced) populations have recently been discovered in North America and Europe. Within the context of the ecology of D. suzukii and its parasitoids, we discuss advantages and disadvantages of estimating larval parasitism levels using different methods, including naturally collected fruit samples and sentinel baits. For most situations, we recommend repeated sampling of naturally occurring fruit rather than using sentinel baits to monitor seasonal dynamics of host plant-Drosophila-parasitoid associations. We describe how to separate Drosophilidae puparia from host fruit material in order to accurately estimate parasitism levels and establish host-parasitoid associations. We provide instructions for identification of emerging parasitoids and include a key to the common families of parasitoids of D. suzukii. We anticipate that the guidelines for methodology and interpretation of results that we provide here will form the basis for a large, multi-research team sampling effort in the coming years to characterize the biological control and nontarget impacts of accidentally and intentionally introduced larval parasitoids of D. suzukii in several regions of the world.

Evaluating invasion risk and population dynamics of the brown marmorated stink bug across the contiguous United States.

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.

Leptographium tereforme sp. nov. and other Ophiostomatales isolated from the root-feeding bark beetle Hylurgus ligniperda in California.

The redhaired pine bark beetle Hylurgus ligniperda (F.) is native to Europe but was discovered in Los Angeles, California, in 2003. This root-and stump-feeding beetle is a common vector of Ophiostomatales, which are potential tree pathogens or causes of blue stain of conifer sapwood. In this study Ophiostomatales were isolated on a cycloheximide-amended medium from 118 adult H. ligniperda collected from infested logs of Pinus halepensis and P. pinea at two sites in California. In total eight species of Ophiostomatales were identified and seven species that occasionally were isolated were unidentified. The most frequently isolated species were Ophiostoma ips and Grosmannia galeiforme, which were isolated respectively from 31% and 23% of the 118 beetles. The other species isolated included O. piceae (isolated from 9% of the beetles), O. querci (8%) and Leptographium tereforme sp. nov. (6%). Grosmannia huntii, L. serpens, three Sporothrix species, O. floccosum, O. stenoceras, two unidentified Hyalorhinocladiella sp. and a sterile fungus each were isolated from fewer then 5% of beetles. Most of the identified species already were known in USA and have been found in association with H. ligniperda in other countries. However the new species, L. tereforme, and G. galeiforme were recorded from USA for the first time, and this is the first report of L. serpens from western North America.

Drosophila suzukii (Diptera: Drosophilidae): A Decade of Research Towards a Sustainable Integrated Pest Management Program.

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.

Fatty Acid Profile as an Indicator of Larval Host for Adult Drosophila suzukii.

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.

Floral Resources for Trissolcus japonicus, a Parasitoid of Halyomorpha halys.

The egg parasitoid Trissolcus japonicus is the main candidate for classical biocontrol of the invasive agricultural pest Halyomorpha halys. The efficacy of classical biocontrol depends on the parasitoid's survival and conservation in the agroecosystem. Most parasitoid species rely on floral nectar as a food source, thus identifying nectar sources for T. japonicus is critical. We evaluated the impact of eight flowering plant species on T. japonicus survival in the lab by exposing unfed wasps to flowers inside vials. We also measured the wasps' nutrient levels to confirm feeding and energy storage using anthrone and vanillin assays adapted for T. japonicus. Buckwheat, cilantro, and dill provided the best nectar sources for T. japonicus by improving median survival by 15, 3.5, and 17.5 days compared to water. These three nectar sources increased wasps' sugar levels, and cilantro and dill also increased glycogen levels. Sweet alyssum, marigold, crimson clover, yellow mustard, and phacelia did not improve wasp survival or nutrient reserves. Further research is needed to determine if these flowers maintain their benefits in the field and whether they will increase the parasitism rate of H. halys.