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Evaluation of the invasion dynamics of non-native species and associated socio-ecological impacts : the case study of Vespa velutina
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Resumo(s)
Invasive species are considered one of the greatest threats to the conservation of biodiversity and ecosystem services, putting at risk human health and economic activities. An example of a successful invasive species is the yellow-legged hornet, Vespa velutina nigrithorax (hereafter V. velutina). Originally from China, this species was first found in Europe in 2004 in the Bordeaux region of France. Since then, it has been expanding, being now present in ten western European countries, including Portugal. Since 2016 V. velutina has been considered by the European Union an invasive that requires monitoring and control. Knowing the potential of V. velutina for further expansion and its probable dispersal routes is crucial to anticipate its arrival and define adequate management practices. This species readily adapts to urban and agricultural environments and, as a voracious predator of honeybees and wild pollinators, is causing serious impacts on human health, on beekeeping and agricultural economies, and on native biodiversity. Here, I intend to generate new knowledge about V. velutina and deliver novel recommendations for future action plans for this invasive. The main goals of this work were: (i) explore the niche dynamics and the potential for further expansion in Europe; (ii) explore the dispersal patterns in Portugal and assess which drivers have been influential for each; (iii) develop a new molecular method to identify the best sample to study predation on honeybees and other wild insects; (iv) assess the perception of Portuguese beekeepers about the impacts on their beekeeping activity; (v) assess whether V. velutina can have qualitatively different impacts at different densities as the invasion proceeds. In general, the results showed that V. velutina still has enormous potential for expansion in Europe, because a large area of the continent has favourable environmental conditions for the species, and that its dispersal is facilitated by human activities, namely along motorways. The results also confirmed V. velutina as an additional stress for native biodiversity and for beekeeping, agricultural and forestry activities. Indeed, metabarcoding analysis of V. velutina larvae faecal pellets revealed the presence of honeybee DNA in all analysed colonies, irrespective of their location. Moreover, at initial stages of invasion, V. velutina poses major risks more frequently in urban and rural areas; only later, when at high densities, it can become a risk to humans engaged with forestry activities (e.g., loggers). The results of this thesis have relevant implications for ongoing monitoring control actions that will help mitigate the impacts of V. velutina and hamper its ongoing expansion.
Descrição
Palavras-chave
Análise de dieta Dinâmica de invasão Dispersão Espécies invasoras Impactos socio-ecológicos Modelos de distribuição de espécies Vespa velutina Diet analysis Dispersion pathways Distribution models Invasion dynamics Invasive species Socio-ecological impacts