Impacts of the invasive hornet Vespa velutina on native wasp species: a first effort to understand population-level effects in an invaded area of Europe

Abstract

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.

Invasion potential of hornets (Hymenoptera: Vespidae: Vespa spp.)

“…Peripheral populations in the Iberian Peninsula, northwestern Italy, and the United Kingdom have even further reduced genetic diversity compared to the population in France from which they are derived, indicating there have been no additional gynes introduced from Asia ( 125 , 139 ), yet the species continues to expand its distribution in Europe. It is not yet clear which aspects of its biology have enabled its dramatic success there ( 241 , 242 ), although a contributing factor may be its larger colonies and greater production of gynes compared to endemic V. crabro colonies ( 78 ). The invasion of South Korea has proceeded more slowly than that of France ( 12 , 62 , 90 , 243 ).…”

“…Vespa velutina preys extensively on honey bees (especially A. mellifera L.), syrphid flies, social wasps, and other pollinators ( 17 , 22 , 182 , 187 , 241 , 245 , 246 , 250 – 253 ). In some instances, intense predation by V. velutina workers foraging on insects at flowers can diminish overall pollination of plants ( 254 ).…”

“…Recent studies have provided insights into differences in the ecology and behavior of V. crabro relative to the invasive V. velutina in northwestern Italy, in an attempt to better understand the very different abundances and impacts of these two species. One study detected no evidence of competition between V. crabro and V. velutina ( 241 ), perhaps because their niches and preferred habitats only partially overlap. Another found no substantial differences in behavioral traits (e.g., boldness, exploratory tendency, durations of foraging-related variables) ( 242 ).…”

Comparison of Effectiveness and Selectiveness of Baited Traps for the Capture of the Invasive Hornet Vespa velutina

“…During the invasion process of V. velutina , baited traps have been used with different purposes, such as a sampling method for testing scientific hypotheses or as part of surveillance and control strategies against the invasive species. In the first case, for example, these have been used to assess the abundance of the invasive population of V. velutina across seasons and/or sites within regions [ 1 , 13 , 46 ], study the environmental conditions associated with the invasion [ 30 ], or assess causal effects over native populations [ 47 ]. In the second case, these have been successfully employed in order to detect the arrival of the species into new regions [ 48 ], to monitor the expansion of or decline in the population [ 21 , 49 ], or as a part of the eradication strategy during the establishing period in a Mediterranean island [ 21 ].…”

Host Range Expansion of Nest-Parasitic Moths Pyralis regalis and Hypsopygia mauritialis in Social Wasp Nests: New Findings and Implications for Biological Control

“…The invasive alien hornet, V. velutina nigrithorax, which was introduced to the Republic of Korea from China in 2003, has spread throughout the Republic of Korea [18,44] and Europe, causing negative impacts [45]. Only few natural enemies of this hornet were ever documented in Europe and the Republic of Korea, where the conopid fly [46], nematode [47], and marten [48] have been studied as predators.…”