Contrasting patterns from two invasion fronts suggest a niche shift of an invasive predator of native bees

Abstract

Background The accuracy of predictions of invasive species ranges is dependent on niche similarity between invasive and native populations and on our ability to identify the niche characteristics. With this work we aimed to compare the niche dynamics of two genetically related invasive populations of Vespa velutina (an effective predator of honeybees and wild pollinators), in two distinct climatic regions, one in central Europe and another one in the north-western Iberian Peninsula, and hence to identify uninvaded regions susceptible to invasion. Methods Niche dynamics and shifts of V. velutina were assessed by comparing the environmental niches of the native and of the two invasive populations, using climatic, topographic and land use variables. We also ran reciprocal distribution models using different algorithms and records from both native and invasive ranges to compare model predictions and estimate which regions are at a greater risk of being invaded. Results An apparent niche shift was detected in the population of the NW of Iberian Peninsula, where the species is living under environmental conditions different from the native niche. In central Europe, large suitable areas remain unoccupied. The fact that both invasive populations are well established, despite occupying environmentally distinct regions indicates that V. velutina has a high ability to successfully invade different environmental envelopes from those existing in its native range. For example, in north-western Iberian Peninsula the species is now thriving out of its native niche limits. Moreover, the large extent of still unoccupied environmental space with similar conditions to those used by the species in its native range suggests that there is still a large area of central and eastern Europe that can be potentially invaded by the species.

On the Evidence of the European Bee-Eater (<em>Merops apiaster</em>) as a Predator of the Yellow-Legged Hornet (<em>Vespa velutina</em>) and its Potential Contribution as a Biological Control Agent

“…Yet, no matter how much YLH the EBE captures, this effort will only be effective in areas where both species, prey and predator, cohabit. Indeed, contrary to what happens with the European Honey-buzzard, a predator specialized in Vespidae and which in France, Spain and Portugal has already been confirmed to feed on combs from YLH nests [47][48][49][50], and whose distribution ranges in Europe, both in the present and in future predictions, seem to overlap reasonably [17,19,[65][66][67], the same does not seem to occur always with EBE.…”

“…The two species, the YLH and the EBE, seem to have somewhat different climate niches, with the YLH preferring wetter and fairly cooler regions [10,19,21,32,74,75], while the EBE, as a thermophilic species, prefers regions of greater aridity, that is, hotter and drier [56,58,76,77,78,79,80,81]. For this reason, on a country-wide scale, the current area of sympatry between the two species does not appear to be particularly large, namely in the Iberian Peninsula (IP), as illustrated in Figure 4, which, despite some flaws (e.g.…”

“…For this reason, on a country-wide scale, the current area of sympatry between the two species does not appear to be particularly large, namely in the Iberian Peninsula (IP), as illustrated in Figure 4, which, despite some flaws (e.g. in Eng- land), reasonably reflects the distribution of the invasive wasp [19,73,82] and the EBE [67] in Europe. Presently, in Portugal, the overlap between the areas of occurrence of the two species is not very large, as already mentioned, and in Spain the disjunction seems to be much more evident (cf.…”

“…Several researchers claim that it is now impossible or nearly impossible to eradicate the YLH [7,9,13], which will continue to spread in the countries where it is already present [10,14,15], and that in the long term or even in a few years it will very likely spread over most of the rest of Central, Eastern and Southeastern Europe [1,13,[16][17][18][19]. Even with the application of the current methods of destruction of the exotic hornet by the authorities and beekeepers (surveillance, use of baited traps, location and destruction of nests), the spread has been unstoppable [9,20,21].…”

“…However, the importance of predation also depends on other factors, such as the geographic coexistence between both species, predator and prey, and although the potential area of occurrence of YLH in Europe (see Verdasca et al [19] or GBIF Secretariat [65], among others), coincides very reasonably with the distribution range of the European Honey Buzzard [66,67], the same does not seem to happen with the EBE, at least in the present and in certain regions of Europe [67,68].…”