The Asian vinegar fly Drosophila suzukii (spotted wing Drosophila [SWD]) has emerged as a major invasive insect pest of small and stone fruits in both the Americas and Europe since the late 2000s. While research efforts have rapidly progressed in Asia, North America, and Europe over the past 5 years, important new insights may be gained in comparing and contrasting findings across the regions affected by SWD. In this review, we explore common themes in the invasion biology of SWD by examining (1) its biology and current pest status in endemic and recently invaded regions; (2) current efforts and future research needs for the development of predictive models for its geographic expansion; and (3) prospects for both natural and classical (=importation) biological control of SWD in invaded habitats, with emphasis on the role of hymenopteran parasitoids. We conclude that particularly fruitful areas of research should include fundamental studies of its overwintering, host-use, and dispersal capabilities; as well as applied studies of alternative, cost-effective management techniques to complement insecticide use within the integrated pest management framework. Finally, we emphasize that outreach efforts are critical to effective SWD management by highlighting successful Communicated by M. Traugott. Electronic supplementary materialThe online version of this article (strategies and insights gained from various geographic regions.Keywords Biological control Á Drosophila Á Frugivore Á Integrated pest management Á Invasion biology Key message• Spotted wing Drosophila (SWD) is a major invasive pest of soft fruits in the Americas and Europe. • We review the current global distribution and economic impacts of SWD, develop models for predicting its further spread, and discuss the prospects for biological control of this pest. • The following research areas into SWD biology appear particularly promising: its biology at low temperatures, the dispersal and migratory abilities of adults, and exploration in Asian regions for potential classical biological control agents.

Abstract. The impact of non-native plant invasions on ecosystems has been controversial because obvious local effects have not yet led to the global extinction of any native plant species on continents and large islands. We suggest that extinction is not the appropriate measure of impact on ecosystem function and present evidence that non-native plant invasions or the replacement of native plants with non-native ornamentals results in significant bottom-up reductions of energy available for local food webs. Using replicated common gardens we compared Lepidoptera species richness and abundance on native plants, non-native congeners of those natives, and non-native species with no close relatives in the study area. Non-native plants supported significantly fewer caterpillars of significantly fewer specialist and generalist species even when the non-natives were close relatives of native host plants. However, the effect size was smaller in the latter category indicating phylogenetic similarity to local natives may positively impact herbivory. Cluster analysis revealed that a non-native plant congener often supports a lepidopteran community that is a subset of the similar, but more diverse community found on its native congener. The proportion of the Lepidoptera community consisting of specialist species was about five times larger across native species within sites compared to non-native plant species. In addition, species accumulation trajectories suggested that in a fully sampled community the differences between the Lepidoptera supported by native and non-native plants may be even greater than presented here.

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Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), has become the most destructive insect pest of cruciferous vegetables (Brassica oleracea L.) worldwide, and is a continuing problem especially in the southern United States. Because of inconsistencies in individual control methods, inefficiencies and time demands of scouting, and the lack of clear thresholds, current management practices emphasize the prophylactic use of insecticides. Numerous other methods are available for the management of P. xylostella including host plant resistance, biological controls, cultural controls, behavioral management, and judicious use of insecticides. Past experience has shown that alone, none of these strategies will work sufficiently and insecticide misuse and resistance issues will likely continue. However, when used together, these tactics can complement each other and lead to a more sustainable system. Recent research focused on the molecular genetics and genomics of P. xylostella has dramatically increased our understanding of specific mechanisms controlling P. xylostella physiology and its interactions with plants. This has the potential to revolutionize the way we manage this pest. Here we summarize the natural history and ecology of diamondback moth and present options for its sampling and management. Additionally, we highlight recent research that may lead to a more integrated approach to managing this pest and the suite of other insect pests of Brassica crops.

Plant defenses often mediate whether competing chewing and sucking herbivores indirectly benefit or harm one another. Dual-guild herbivory also can muddle plant signals used by specialist natural enemies to locate prey, further complicating the net impact of herbivore-herbivore interactions in naturally diverse settings. While dual-guild herbivore communities are common in nature, consequences for top-down processes are unclear, as chemically mediated tri-trophic interactions are rarely evaluated in field environments. Combining observational and experimental approaches in the open field, we test a prediction that chewing herbivores interfere with top-down suppression of phloem feeders on Brassica oleracea across broad landscapes. In a two-year survey of 52 working farm sites, we found that parasitoid and aphid densities on broccoli plants positively correlated at farms where aphids and caterpillars rarely co-occurred, but this relationship disappeared at farms where caterpillars commonly co-occurred. In a follow-up experiment, we compared single and dual-guild herbivore communities at four local farm sites and found that caterpillars (P. rapae) caused a 30% reduction in aphid parasitism (primarily by Diaeretiella rapae), and increased aphid colony (Brevicoryne brassicae) growth at some sites. Notably, in the absence of predators, caterpillars indirectly suppressed, rather than enhanced, aphid growth. Amid considerable ecological noise, our study reveals a pattern of apparent commensalism: herbivore-herbivore facilitation via relaxed top-down suppression. This work suggests that enemy-mediated apparent commensalism may override constraints to growth induced by competing herbivores in field environments, and emphasizes the value of placing chemically mediated interactions within their broader environmental and community contexts.