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.

Spotted wing drosophila, Drosophila suzukii, is a globally invasive pest of soft-skinned fruit. Females oviposit into ripening fruit and larvae cause direct destruction of tissues. As many plant essential oils are permitted food additives, they may provide a safe means of protecting fruit from D. suzukii infestation in both conventional and organic production systems. Twelve oils and potassium metabisulfite (KMS) were screened in the laboratory as repellents for D. suzukii flies. Most essential oils deterred D. suzukii flies from cotton wicks containing attractive raspberry juice. Peppermint oil was particularly effective, preventing almost all flies from contacting treated wicks and remaining 100% repellent for 6 d post-application. Thyme oil was unique because it caused high male mortality and reduced the number of responding flies compared to other oils. KMS was not found to be repellent to D. suzukii, but may have fumigant properties, particularly at high concentrations. Peppermint oil appears to be the best candidate for field testing to determine the effectiveness and feasibility of using essential oils as part of a push-pull management strategy against D. suzukii. This is the first time that essential oils have been evaluated and proven effective in preventing fruit-infesting flies from contacting attractive stimuli.

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Drosophila suzukii Matsumura is an economically important pest of soft and small fruit crops. Unlike other drosophilid flies, D. suzukii is capable of infesting ripe and partially ripe fruit, which poses a significant pest management challenge, as there is no tolerance for infested or damaged fruit in the marketplace. As a result, producers in many regions rely on calendar-scheduled insecticide applications for D. suzukii management. In order to develop an integrated pest management approach, better tools for monitoring adult fly populations are needed. Over two growing seasons in southern Ontario, we evaluated three commercial (Pherocon SWD dual-lure, Suzukii Trap, and Scentry Lure) and two homemade baits (apple cider vinegar and yeast + sugar water) for their ability to capture D. suzukii in raspberry and highbush blueberry fields. In general, commercial attractants captured D. suzukii earlier in the growing season and in greater numbers, with fewer nontarget captures, compared with homemade baits. Scentry Lure tended to perform better than other attractants, capturing D. suzukii earlier and in larger numbers during peak harvest. Pherocon SWD dual-lure was highly specific to D. suzukii. The combination of Scentry Lure with Suzukii Trap had possible synergistic effects, as numbers of D. suzukii captured to the combined treatment were more than additive. Using commercial attractants improves D. suzukii monitoring and will allow growers to improve the timing of insecticide applications with D. suzukii activity in the field.

Drosophila suzukii (Matsumura) is a recent invasive pest of soft fruits in North and South America and Europe. Control relies on frequent applications of synthetic insecticides. Additional tactics are needed for development of an effective integrated pest management program. Study objectives were to evaluate the repellency and oviposition deterrent capability of compounds in plant essential oils and the effect of select compounds on infestation rates in strawberries, using laminate polymer flakes as a carrier. Of 14 compounds from 5 essential oils, thymol was the most repellent to adult D. suzukii males and females for up to 24 h in the laboratory. Citronellol, geraniol and menthol were moderately repellent. In a choice assay, thymol on cotton wicks adjacent to ripe raspberries reduced female fly landings and larval infestation levels. In a no-choice assay, thymol reduced female fly landings by 60%, larval infestation by 50% and increased fly mortality compared to controls. Neither citronellol alone nor a blend of four repellent compounds was as effective as thymol alone at reducing fly landing, larval infestation, or increasing fly mortality. In a choice assay using polymer flakes, larval infestation was greater in raspberries near untreated flakes than in raspberries near flakes treated with thymol or peppermint oil. In the field, thymol and peppermint flakes reduced larval infestation levels by 25% in strawberries at 4, but not 7, days after application, compared to untreated flakes. With future improvements in application strategies, deterrent compounds may have a role in improving the management of D. suzukii.

Biological control of insects by predators may be indirectly influenced by management practices that change the invertebrate community in agroecosystems. In this study we examined effects that mulching and weeding have on predatory beetles (Carabidae and Staphylinidae) and their potential prey in a highbush blueberry field. We compared beetle communities in unweeded control plots to those that were weeded and/or received a single application of compost or pine needle mulch. Compost mulch and weeding significantly affected the carabid community while the staphylinid community responded to compost and pine needle mulches. Effects because of mulch tended to intensify in the year after mulch application for both families. Estimates of species richness and diversity for Carabidae and Staphylinidae were similar in all plot types, but rarefaction curves suggested higher Carabidae richness in unmulched plots despite fewer individuals captured. Carnivorous Carabidae, dominated by Pterostichus melanarius, were most frequently captured in compost plots both years, and omnivores were most frequently captured in unweeded compost. Density of millipedes, the most abundant potential prey, was generally greater in mulched plots, whereas seasonal abundance of small earthworms varied among mulch types. Our results have potential implications for biological control in mulched highbush blueberries depending on beetle consumption rates for key pests and how rates are affected by alternative prey.

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The twospotted spider mite (Tetranychus urticae) is a serious pest of strawberries. The objectives of this study were to determine incidence and severity of twospotted spider mite infestations on transplants and the potential for steam to eliminate them. Mites occurred on transplants of Florida cultivars from each of eight North American nurseries from which samples were obtained, but levels were usually low (59% of samples had zero mites). Estimated complete mortality of twospotted spider mite adult females and eggs on leaf discs using steam at 48°C was 2.7 and 1.9 h, respectively; 44°C and 46°C for up to 4 h killed 20% and 60% of the mites, respectively. Based on these results, eliminating twospotted spider mites on transplants is feasible and may be valuable for improving their management in fruit-production fields.