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.

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

斑翅果蝇(Drosophila suzukii Matsumura)传播速度快,危害多种水果,已经引起广泛重视。其形态鉴别特征是雄虫翅翼边缘末端以第1翅脉为中心有一块清晰的黑斑,雌虫产卵器为坚硬的锯齿状,可将卵直接产于成熟或即将成熟的果实内。斑翅果蝇繁殖速度快,1 a可繁殖3~10代,雌蝇终生产卵200~600粒。糖醋液诱捕监测以及果园清洁处理是害虫防治的必要措施。有机磷、拟除虫菊酯、多杀霉素等农药都有很好的局部触杀和残留杀虫活性。

斑翅果蝇(Drosophila suzukii)研究现状

After its initial discovery in California in 2008, Drosophila suzukii Matsumura has become one of the most important invasive agricultural pest insects across climate zones in much of Asia, Europe, North America, and South America. Populations of D. suzukii have demonstrated notable behavioral and physiological plasticity, adapting to diverse environmental and climatic conditions, interspecific competition, novel food sources, and potential predators. This adaptability and plasticity have enabled rapid range expansion and diversified niche use by D. suzukii, making it a species particularly suited to changing habitats and conditions. This article reviews factors and evidence that influence plasticity in D. suzukii and promotes this species' invasiveness.

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Plasticity Is Key to Success of Drosophila suzukii (Diptera: Drosophilidae) Invasion.

Spotted wing drosophila, Drosophila suzukii Matsumura, is a major pest of small fruit worldwide in temperate and subtropical growing regions. In Northern climates, D. suzukii likely overwinters locally under leaf litter and snow pack, but our understanding of the factors affecting thermal susceptibility is limited. While previous investigations of thermal susceptibility in this species have employed conventional static acclimation protocols, we aimed to determine whether gradual cooling, or dynamic acclimation, may extend the limits of known thermal tolerance by more closely approximating naturally occurring shifts in temperature. First, we assessed survival among adult and pupal D. suzukii using static acclimation. Then, we re-assessed survival using a novel dynamic acclimation method. We found that while static acclimation was sufficient to induce cold tolerance, dynamic acclimation significantly improved survival at temperatures as low as −7.5 °C. Following static acclimation, the lower lethal limit of adult D. suzukii was −1.1 °C in winter morphotype (WM) adults compared to 1.7 °C in non-acclimated summer morphotype (SM) adults. Dynamic acclimation reduced the lower limit to −5 °C in SM flies. At the end of our study 50% of WM flies survived 72 h at −7.5 °C. Below 0 °C pupal survival declined significantly regardless of acclimation procedure. However, pupal acclimation improved survival outcomes significantly compared to non-acclimated pupae, suggesting that while juvenile diapause is unlikely, cold hardening likely benefits those flies which may develop into the overwintering WM population. These data suggest that the degree of cold hardening is proportional to the thermal environment, a finding previously unrecognized in this species. Given the economic impact of this pest, these data may have important implications for offseason population monitoring and management. We discuss how phenotypic plasticity may drive geographical range expansion, and the impact of climate change on the spread of this species.

Phenotypic Plasticity Promotes Overwintering Survival in A Globally Invasive Crop Pest, Drosophila suzukii.

The mechanisms allowing the widespread invasive pest Drosophila suzukii to survive from early spring until the availability of the first fruit crops are still unclear. Seasonal biology and population dynamics of D. suzukii were investigated in order to better understand the contribution of the early spring hosts to the infestation of the first fruit crops of the season. We identified hosts available to D. suzukii in early spring and assessed their suitability for the pest oviposition and reproductive success under field and laboratory conditions. The natural infestation rate of one of these hosts, Aucuba japonica, was assessed over springtime and the morphology of the flies that emerged from infested A. japonica fruits was characterized under field conditions. Then, these findings were correlated with long-term monitoring data on seasonal reproductive biology and morphology of the pest, using a cumulative degree-days (DD) analysis. Field sampling revealed that overwintered D. suzukii females were physiologically able to lay eggs at 87 DD which coincided with the detection of the first infested early spring hosts. The latter were continuously and increasingly infested by D. suzukii eggs in nature from early spring until the end of May, in particular Aucuba japonica. Individuals emerged from most of these hosts were characterized by a poor fitness and a rather low success of emergence. In the field, only few summer morphs emerged from naturally infested A. japonica fruits around the end of May-beginning of June. However, field monitoring in orchards revealed that D. suzukii individuals consisted solely of winter morphs until mid-June. These observations indicate that overwintered D. suzukii females are the predominant source for the infestations in the first available fruit crops of the season. We discuss these findings in the context of possible pest control strategies.

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Overwintered Drosophila suzukii Are the Main Source for Infestations of the First Fruit Crops of the Season

Spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), was monitored from 2010 to 2014 in 314-828 sites located in interior fruit-growing regions of OR and WA, United States, and BC, Canada, using traps baited with apple cider vinegar or sugar-water-yeast. Seasonal population dynamics and sex ratios were summarized for berry, cherry, stone fruit, grape, non-crop host plants, non-host sites, and for conventional IPM, certified organic, backyard, and feral sites, by region and year. Overwintering was detected in all regions and years, despite winter temperatures below -17°C. A spatial analysis was conducted using a Geographic Information System (GIS), daily weather data, geomorphometric measures of terrain, distance to water, and other variables, at each site. Overwintering success at a site, measured as Julian week of first capture of D. suzukii, was significantly related (R2 = 0.49) in cherry habitats to year, agronomic treatment, and number of winter days with temperatures >-5°C. In berry, cherry, stone fruit and grape habitats, 2011-2014, it was significantly related (R2 = 0.42) to year, agronomic treatment, the logarithm of peak population of D. suzukii in the prior autumn, latitude, elevation, and topographic wetness index. The results show that D. suzukii has adapted to exploit a succession of irrigated crops and feral habitats in mixed landscapes of a semi-arid region with cold winters and hot dry summers, and are shaping strategies for pest management and for biological control.

Spatial Analysis of Seasonal Dynamics and Overwintering of Drosophila suzukii (Diptera: Drosophilidae) in the Okanagan-Columbia Basin, 2010–2014

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), was first detected in 2009 in the Okanagan Basin, British Columbia, Canada. During 2010–2016, 94 570 fruits of 35 non-crop species, from 12 plant families, were collected from 101 sites where adult D. suzukii flies were trapped, and incubated in a controlled environment. In total, 450 adult D. suzukii emerged from 62 of 929 fruit collections, and from 10 host plant species in five families, of which six species are native to the region. Five plant species are reported for the first time as hosts of D. suzukii, and 11 species for the first time as non-hosts. Measures of fly occurrence and infestation reveal it to be relatively abundant in five hosts and low in others. The fly reproduced in a succession of host plants, with first infestation of each from mid-July through mid-September, and was present until mid-October, but overwintering stages were not found. Degree-day accumulations for the infested period suggest that three to five generations of D. suzukii developed on non-crop plants and formed a large contribution to the annual increases observed in trap counts in a semi-arid cold winter climate, with implications for many strategies of pest management.

Brigitte M Rozema

Papers

Spatial Analysis of Seasonal Dynamics and Overwintering of Drosophila suzukii (Diptera: Drosophilidae) in the Okanagan-Columbia Basin, 2010–2014

Infestation and timing of use of non-crop plants by Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) in the Okanagan Basin, Canada