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Argentine ants harm nestlings of the blue tit

The consequences of ant invasions on ecosystems may only become apparent after long periods. In addition, predicting how sensitive native fauna will respond is only possible if the underlying proximate mechanisms of their impact are identified. The attraction of the native and invasive ant community to artificial bird nests was studied, together with reproduction of a wild native songbird over five consecutive breeding seasons in relation to the presence of an invasive ant species. Biometric, reproductive and individual blood parameters of great tits Parus major breeding in invaded as compared to uninvaded sites by Argentine ants Linepithema humile were analysed. Great tits bred preferably in uninvaded territories by the Argentine ant. Moreover, Argentine ants were more abundant at nests in invaded sites, than any native ant species were at uninvaded sites. Further, Argentine ants recruited at the artificial nests more intensively and responded to a larger variety of nest (intact eggs, cracked eggs, faeces, and cracked eggs plus faeces) contents than native species. Although breeding success and adult condition did not vary in relation to invasion status, offspring quality was negatively affected by the presence of Argentine ants. Nestlings reared in invaded sites were lighter, with lower wing/tarsus length ratio and had a reduced nutritional condition and altered oxidative stress balance as measured from several blood parameters. The interspersed distribution and small distance between invaded versus uninvaded territories suggest that ant presence affects nestling condition through direct interference at the nest. These results highlight the importance of evaluating the proximate effects like physiological parameters of the native fauna, when studying invasive ant-native bird interactions. informacion[at] Álvarez et al (2020) Breeding consequences for a songbird nesting in Argentine ant' invaded land. Biol Invasions
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Generalized hybridization between commercial and native individuals of bumble bees

Generalized hybridization between commercial and native individuals of bumble bees

Every year more than 1 million commercial bumblebee colonies are deployed in greenhouses worldwide for their pollination services. While commercial pollinators have been an enormous benefit for crop production, their use is emerging as an important threat. Commercial pollinators have been linked to pathogen spillover, and their introduction outside their native area has had devastating effects on native pollinators. A more pervasive but underappreciated threat is their potential impact on the genetic integrity of native pollinators. A sampling and genotyping?plus?phenotyping protocol was set up to evaluate the presence and extent of hybridization between commercial and native individuals of Bombus terrestris in south?western Spain, a region experiencing a huge propagule pressure of non?native genotypes due to the massive use of commercial colonies for crop pollination. Genomic data show clear evidence of generalized hybridization between native and introduced commercial bumblebee lineages in southern Spain. Only 19% of analysed individuals were assigned with high confidence to the pure native genetic cluster and >45% of sampled specimens were first?generation hybrids or backcrosses between native and commercial genotypes, indicating that genetic introgression is pervasive in southern Spain. Although the frequency of commercial genotypes sharply declined with the distance to greenhouses, non?native alleles have introgressed into native populations inhabiting protected natural parks >60 km away from commercial bumblebee release areas. As pollination services demand will increase in the coming years, only a more restrictive regulation of commercial lines could mitigate their negative impacts on the genetic integrity of native pollinators, avoid processes of genetic homogenization, and prevent the potential disruption of local adaptations. informacion[at] Bartomeus et al (2020) Safeguarding the genetic integrity of native pollinators requires stronger regulations on commercial lines. Ecological Solutions and Evidences. Doi 10.1002/2688-8319.12012