All That Glitters Is Not Gold: The Other Insects That Fall into the Asian Yellow-Legged Hornet Vespa velutina ‘Specific’ Traps

Simple Summary The recent spreading of the invasive Asian hornet (Vespa velutina) to the Iberian Peninsula has led to the application of management measures to control and mitigate its impact on receiving environments. Among the most used control methods are capture traps, which use a sugary attractant to catch the invasive wasps. However, although the used V. velutina traps are presumably specific, they do not only attract V. velutina specimens, but also a large number of non-target species that are also captured. In the present work, the species of insects that unintentionally fall into the capture traps of V. velutina have been specifically identified, as well as their implications for ecosystem and for human activities. A total of 74 non-target taxa of insects were caught by the V. velutina trapping in northern Spain. Most of them were flies, mosquitoes, wasps and moths, being all highly important groups from the biological, ecological and economical points of view. Surprisingly, the most abundant trapped species was the invasive fly, Drosophila suzukii that represented the 36.07% of the total catches. Furthermore, we reported the first record of ectoparasitic mites of the genus Varroa on V. velutina, constituting a newly recorded symbiotic association. Abstract The introduction of invasive species is considered one of the major threats to the biodiversity conservation worldwide. In recent years, an Asian invasive species of wasp has set off alarms in Europe and elsewhere in the world, Vespa velutina. The Asian wasp was accidentally introduced in France around 2004 and shortly thereafter it was able to colonise practically all of Europe, including the Iberian Peninsula. The ecological and economic implications of V. velutina invasion and its high colonisation ability have triggered widespread trapping campaigns, usually supported by beekeepers and local governments, with the aim of diminishing its population and its negative impacts. Among the most used control methods are the capture traps, which use a sugary attractant to catch the invasive wasps. However, the species-specific selectivity and efficiency of these traps has been little studied. In this paper, we have analysed the specific identity of the unintentionally trapped insect species from northern Spain (covering one-year period), as well as we have assessed the provided ecosystem services by them. A total of 74 non-target taxa of insects were caught by the V. velutina studied traps, most of them correspond to the orders Diptera, Hymenoptera and Lepidoptera, the dipterans being the most abundant group. Surprisingly, the most abundant trapped species was the invasive fly, Drosophila suzukii that represented the 36.07% of the total catches. Furthermore, we reported the first record of ectoparasitic mites of the genus Varroa on V. velutina, constituting a newly recorded symbiotic association. Hopefully, the provided information helps to develop new protocols and management tools to control this invasive species in the Iberian Peninsula and other temperate areas of western Europe and the Mediterranean basin.