Vespa velutina, or Asian yellow-legged hornet, was accidentally introduced from China to other parts of the world: South Korea in 2003, Europe in 2004, and Japan in 2012. V. velutina represents a serious threat to native pollinators. It is known to be a fierce predator of honey bees, but can also hunt wild bees, native wasps, and other flying insects. When V. velutina colonies are developed, many hornets capture foraging bees which are coming back to their hives, causing an increase in homing failure and paralysis of foraging thus leading to colony collapse. The hornets may enter weak beehives to prey on brood and pillage honey. Unlike Apis cerana, Apis mellifera is unable to cope with the predation pressure of V. velutina. Monitoring the spread of an invasive alien species is crucial to plan appropriate management actions and activities to limit the expansion of the species. In addition, an early detection of V. velutina in areas far away from the expansion front allows a rapid response aimed to remove these isolated populations before the settlement of the species. Where V. velutina is now established, control measures to prevent colony losses must be implemented with an integrated pest management approach.

The introduction and expansion of the Asian yellow-legged hornet (Vespa velutina nigrithorax) in Europe poses concern for multiple reasons, including biodiversity conservation. In addition to the predation of native insects (e.g., bees and wasps), this species may compete with native hornets due to an overlap of their climatic and trophic niches. The aim of this study is to investigate the realised climatic niche of V. v. nigrithorax and its response to climatic conditions and to evaluate the degree of overlap with the niches of the two native Vespa species present in Europe, Vespa crabro and Vespa orientalis. The niches of both native species partially overlap with the niche of the invasive species (Schoener’s D, 0.43 for V. crabro and 0.28 for V. orientalis), although some differences can be detected. V. crabro appears to be more adapted to cold and dry conditions than the invasive species, and V. orientalis is more adapted to arid climates. These differences may provide a competitive advantage to both native species in areas with a lower environmental suitability for V. v. nigrithorax, in the probable event that this species continues to spread, reaching all areas predicted to be suitable in Europe and in the Mediterranean basin.

Invasive alien species could generate a multitude of impacts towards native species. The introduction and spread of Vespa velutina in Europe is raising concern for the conservation of insect’s biodiversity, including wasps due to predation, competition or a combination of these two mechanisms. Nevertheless, most evidence for negative effects on other wasps are based on laboratory experiments, direct observations, and on considerations about the biology and ecology of Vespidae. No field study in Europe explored how the abundance of V. velutina could affect the population of native Vespidae, as expected in case of competition and predation. We analysed how the abundance of V. velutina influenced that of Vespa crabro, 4 years after the arrival and establishment of V. velutina in our study area, in Italy. Moreover, we compared the abundances of three native Vespidae (V. crabro, Vespula vulgaris, Vespula germanica), between our study area and an adjacent uninvaded area with similar environmental conditions. Bayesian Generalized Linear Models revealed that the abundance of V. velutina and V. crabro was positively associated, where V. velutina was scarce. Covariation disappeared only at those trapping sites where V. velutina was extremely abundant. Moreover, abundances of native wasps were similar between the invaded and the uninvaded areas. Implications for insect conservation: The wide-scale monitoring activity performed to investigate the effects of V. velutina on native wasps has not detected any negative effects in relation to the presence of the invasive species. More effort is however requested for understanding if V. velutina could really affect native Vespidae at the population-level.

Megachile sculpturalis (Smith, 1853) is the first exotic bee species in Europe. Its remarkably fast expansion across this continent is leading to a growing concern on the extent of negative impacts to the native fauna. To evaluate the interactions of exotic bees with local wild bees, we set up trap nests for above-ground nesting bees on a semi-urban area of north-western Italy. We aimed to investigate the interaction in artificial traps between the exotic and native wild bees and to assess offspring traits accounting for exotic bee fitness: progeny sex ratio and incidence of natural enemies. We found that the tunnels occupied by exotic bees were already cohabited by O. cornuta, and thus the cells of later nesting alien bees may block the native bee emergence for the next year. The progeny sex ratio of M. sculpturalis was strongly unbalanced toward males, indicating a temporary adverse population trend in the local invaded area. In addition, we documented the presence of three native natural enemies affecting the brood of the exotic bee. Our results bring out new insights on how the M. sculpturalis indirectly competes with native species and on its performance in new locations.

The global challenge to increase agricultural production goes along with the need of decreasing pesticide risks. The European Union (EU) therefore evaluates and controls the risks posed by pesticides by regulating their authorisation through the science-based Risk Assessment process. Member States can however act in derogation to this process and grant the Emergency Authorisation (EA) of pesticides that are currently non-authorised. To protect the health of humans and the environment, Emergency Authorisations are only permitted in exceptional circumstances of agricultural emergency: their use should be limited (i.e., cannot exceed 120 days and one growing season) and concurrent research on alternative strategies must be enforced. Here, we assessed the impact of the Emergency Authorisations process to human and environmental health. Bees, bioindicators of environmental health, were used as model species. Our research demonstrates that i) Emergency Authorisations are widely used throughout EU Member States (annually granted Emergency Authorisations_{min-max, 2017-2021} = 593-660); ii) 12 % of Emergency Authorisations granted the use of pesticides for longer than prescribed by EU regulations; iii) 37 % of Emergency Authorisations were repeatedly granted over time by the same Member State for the same agricultural purpose (i.e., to control the same pest on the same crop); iv) 21 % of Emergency Authorisations granted the use of Active Substances non-approved by risk assessment (EA-ASs Type3) which consequently contaminate the environment (44 % of environmental biomonitoring studies found EA-AS Type3) while being significantly more toxic to pollinators than regularly approved ASs. To facilitate the implementation of sustainable control strategies towards a safer environment for humans and other animals, we identified the most frequent agricultural emergencies and the key research needs. This first quantitative assessment of the Emergency Authorisation process unveils an enduring state of agricultural emergency that acts in derogation of the EU Regulation, leading to broad human, animal, and environmental implications.