Acute oral toxicity of pesticides for the control of the invasive yellow-legged hornet Vespa velutina nigrithorax (Hymenoptera: Vespidae): a step towards effective management

Abstract The yellow-legged hornet, Vespa velutina subs. nigrithorax Buysson, 1905, is an invasive species in Europe, posing substantial ecological and economic threats. Its biology and behaviour, marked by rapid reproduction and aggressive predation, endangers native insects. This has negative impacts on agriculture, biodiversity, and human safety. Effective control is therefore essential to prevent and minimize their spread and ecological impact. This study assessed the acute oral toxicity on V. v. nigrithorax workers of four commercial insecticide formulations containing acetamiprid, spinosad, cypermethrin, and natural pyrethrins mix as active ingredients. Our findings indicate that acetamiprid and spinosad are the most promising compounds, with acetamiprid inducing rapid mortality at low doses and spinosad causing both lethal and sublethal effects that could disrupt hornet behaviour and colony viability. Given that oral exposure generally resulted in higher toxicity than contact exposure, pest control strategies should incorporate multiple exposure pathways. Further investigations are necessary to confirm efficacy under field conditions and to evaluate potential ecological risks to non-target species. Overall, this study provides critical data to enhance V. v. nigrithorax control and supports the development of more effective and environmentally sustainable control approaches against this invasive species.