Factors affecting the distribution of Vespa velutina reported nests: a management approach

Abstract

Vespa velutina nigritorax Buysson, 1905, is considered one of the most harmful invasive species in Europe. Since its introduction, it has caused numerous instances of human, economic, and ecosystem damage. To address its rapid spread, monitoring programmes have been implemented, many relying on citizen-reported data, however, the invaded range continues to expand. In this study, we aimed to improve the knowledge about V. velutina spatial preferences and activity periods to support the development of more effective management measures. We analysed the extent to which citizen-reported nests could be explained by human population density, land cover and altitude in Galicia (NW Spain). In 2021, we conducted an intensive assessment of nest density in a Galician coniferous forest, and we compared it with nest density obtained by citizen reports. We also monitored hornet activity at nests from October to December 2021 in their natural environment. Our analysis revealed that higher human population density, urban land cover, and altitude were the main factors that explained nest notifications in Galicia. Reported nests in coniferous forests underestimate at least five-fold the densities found in this study. Finally, nest activity declined late in the season, and observation times need to be extended during such periods of low activity to ensure representative sampling. These findings can help to implement appropriate management measures focusing more attention on nests in forest areas and extending the nest removal period.