Competition between the native and the introduced hornets Vespa crabro and Vespa velutina: a comparison of potentially relevant life‐history traits

Abstract

1. Invasive alien species are a major threat to biodiversity. In addition to predation and parasitism, native species might suffer from competition when invasive alien species occupy a similar ecological niche.2. This study focused on the potential interspecific interaction between two hornets: the Asian yellow-legged hornet, Vespa velutina, a high-concern invasive alien species recently arrived in Europe; and the native European hornet, Vespa crabro. The two species share a similar ecological niche and V. velutina is rapidly expanding across Europe, which suggests that V. crabro might suffer from competition.3. Under laboratory-controlled conditions, two life-history traits that might cause the two species to compete were investigated: (i) the ability of workers to find food sources and their flexibility in exploiting them (through individual food item choice tests and exploration assays); and (ii) the worker resistance to pathogens (through immune challenge tests).4. The results show that trophic preference of both species highly overlaps, with a marked dietary preference for honeybees compared with other insect prey and non-prey protein items. No differences were observed in the exploratory behaviour of both species. Finally, constitutive antibacterial activity was greater in workers of the native species than in workers of the invasive hornet.5. This laboratory study provides a first assessment under controlled conditions of the factors affecting competition between workers of two hornet species and proposes a framework to assess, in wild contexts, the magnitude of the competition and the impact of the introduced V. velutina on the native V. crabro.

A molecular approach to studying Hymenoptera diets using polistine wasps

“…We hope that this method will be applied to study the ecology of other nest building Hymenoptera, including native and invasive species such as Asian hornets (Vespa velutina Lepeletier). Regarding the latter, better knowledge of their diet is essential to measure the ecological impact of their invasion and to ensure the conservation of native invertebrate biodiversity and the ecosystem services they provide (Wycke et al 2018;Cini et al 2018). University of Auckland provided financial support for JRB.…”

Assessing immunocompetence in red palm weevil adult and immature stages in response to bacterial challenge and entomopathogenic nematode infection

“…Our first immune challenge was aimed at investigating the immunocompetence of weevils of different stages (larvae, pupae, adults) and sex (only in the adults) with respect to a generic bacterial pathogen. To evaluate the ability of RPW to remove bacterial cells from their hemolymph (i.e., bacterial clearance), individuals were injected with the Gram-negative bacteria Escherichia coli, a common immune elicitor when testing insects' immunity (Daborn et al, 2002;Yang & Cox-Foster, 2005;Tian et al, 2009;Manfredini et al, 2010;Gätschenberger et al, 2013;Cappa et al, 2015;Cini et al, 2018). We chose to measure bacterial clearance as a good proxy of individual immunocompetence since different parameters linked to antimicrobial immune response (e.g., number of hemocytes, phagocytosis, nodule formation, PO activity, en-capsulation response) appear correlated in insects' immunity (Gillespie et al, 1997;Cotter & Wilson, 2002;Lambrechts et al, 2004;Schimd-Hempel, 2005).…”

Interspecific hierarchies from aggressiveness and body size among the invasive alien hornet,Vespa velutina nigrithorax, and five native hornets in South Korea

“…In Europe, where V. velutina invaded in 2004, there was only native hornet species, V. crabro, so that the two species were in close competition because of their similar ecological niche, due overlaps in food preference, nesting sites, and life history [25,26]. However, in Korea, where there are nine native hornets, V. velutina clearly differ in their ecological niche.…”

“…In general, the initial incubation period is determined according to the presence or absence of competing species after the invasion of alien species, and after a certain period of time, when the alien species have a firm ecological niche, the population expands and spreads rapidly [47]. Thus, in Europe where the only competition was V. crabro at the beginning of the invasion [25,26], the annual spread rate was 60-80 km/year [48,49]. In Korea, however, the rate of spread is slower than that of Europe at 10-20 km/year, because 63% of the land is forested, and nine Vespa species already inhabit forests [14,50,51].…”

“…In addition, due to its high density in urban areas, V. velutina has public health impacts such as stinging urban residents, and even causing death [14,15,24]. This species also causes ecosystem disturbance through competition and interference with other Vespa species in nature [25][26][27].…”