Investigating the impact of habitat structure on queen and worker bumblebees in the field

点击翻译按钮获取中文摘要

This research will unravel fundamental aspects of bumblebee behaviour and ecology to show how habitat structure affects bumblebees at different stages in their colony cycle. Bumblebees are key pollinators of wildflowers and crops but their populations are declining worldwide. Although bumblebees have been well-studied in some respects, fundamental aspects of their ecology remain unknown. In this proposal we plan to fill some of these gaps so that we can implement the most effective measures to reverse declines. We have four specific objectives. First, little is known about the dispersal of nest-founding queens in spring, so we will determine the fine-scale spatial genetic structure and behaviour of nest-founding queens and relate this to the distribution of nesting and foraging habitats across an agricultural landscape. Second, although new genetic methods have permitted estimates of the foraging ranges of worker bees, we do not know how workers and colonies use space in relation to the fine-scale structure of their habitat; we will therefore quantify both workers' spatial distribution and habitat structure to determine this relationship. Third, some bumblebee species have long tongues and so are the most effective pollinators of wildflowers and crops in which the floral tube (corolla) is deep. The UK's longest-tongued bumblebee species, Bombus hortorum, remains common but the closely related B. ruderatus is scarce. We will compare the spatial genetic structure of these two species directly in the same landscape in order to elucidate the biological reasons for this difference. Fourth, because our study will take place at a site where targeted measures to provide forage for bumblebees (agri-environment schemes) have already been established, we will be able to use our results to model the impacts of these measures on bumblebee foraging range and nest density. To meet our objectives, we will study the five species B. lapidarius, B. pascuorum, B. terrestris B. hortorum and B. ruderatus, chosen to represent an appropriate range of ecological and behavioural differences. We will use a novel combination of genetic, ecological and modelling methods in a unique field setting: an agricultural landscape (2100ha) in England in which blocks of standardised agri-environment options targeted at insect pollinators have been established as part of an ongoing landscape-scale experiment. Our methods will consist of systematic nonlethal sampling of queens and workers for DNA, followed by microsatellite genotyping coupled with sibship reconstruction (grouping of individuals into families) to determine the spatial genetic distribution of queens and workers. We will also use advanced marking techniques (e.g. radio-frequency identification (RFID), pit-tags) to supplement our genetic investigations of queens and specifically to relate queen space use to the distribution of small mammals (whose nests queens are believed to exploit for nesting and which are already being monitored as part of ongoing studies). Finally, we have already characterized the study landscape using both high-resolution multi-spectral scanners and field surveys. The resulting detailed information on habitat composition and structure, when integrated with our data on bumblebee space use, will allow us accurately to model the impact of habitat structure on the bees. Overall, therefore, this project matches the requirements of the Insect Pollinators Initiative very well. First, because the study is taking place at a site where we have already characterized habitat structure and in which an experimental agri-environment scheme is established, it will serve to advance our understanding of the effects of agriculture and land-use change on bumblebee behaviour and colony dynamics. Second, it will use new tools and data analysis to discover fundamental aspects of bumblebee ecology relevant to pollinator declines from molecular to population levels.