Both landscape and local scale factors matter for the parental investment strategies of the pollinator Osmia caerulescens

Abstract

Bees are important pollinators that use resources from both cropped and natural habitats in agroecosystems, and the amount of extant resources have proven to be critical in the adoption of parental investment decisions. Thus, the mixed effects that resource distribution and the organisms’ foraging and dispersal movements have on parental decisions cannot be adequately evaluated without the use of different spatial scales. We assess the effects of the landscape context and the local habitat type on the offspring traits of Osmia caerulescens L. Bees were obtained from standardized trap-nests established in Mediterranean crops. We analyzed the effects that the percentage of semi-natural habitats, the local habitat type, and the nest hole diameter have on offspring weight, the number of emergent progeny and offspring sex ratio. Both landscape and local scale factors affected the offspring traits in significant and interactive ways, and landscape-scale effects varied depending on local factors. Considering our results and taking into account the implications that offspring traits have on the population persistence, we stress the need to introduce these parameters in future studies. Maintaining agricultural landscape heterogeneity, with high crop diversity and the presence of semi-natural habitats is essential for the persistence of Osmia caerulescens populations.