Ground-nesting bee conservation in lowbush blueberry agroecosystems

点击翻译按钮获取中文摘要

The economic value of pollination services provided by bees for Canadian food crops has been conservatively estimated at $1.2 billion annually, and the contributions of wild species to certain key crops are increasingly recognized. Most of these wild bees are ground nesters, and information on their population dynamics, life histories, and nesting habitats remains sparse. Many small fruit species, such as lowbush blueberry (Vaccinium angustifolium), are economically significant crops in Canada and heavily depend on insects for achieving adequate yields. Lowbush blueberry is pollinated by diverse communities of wild bees, including specialist bees that nest in acidic soil and forage almost entirely on a single plant genus or a small group of plant species. However, these bee communities and specialist species are threatened by land-use change and increasing applications of pesticides. The overall objective of this research program is to better understand the population dynamics of ground-nesting bees in agroecosystems to enhance bee conservation and pollination services. As it harbors diverse bee communities and heavily relies on insect mediated pollination, we use the lowbush blueberry agroecosystem as a model crop system. One important gap in our knowledge of ground-nesting bees is an understanding of why and how female bees decide to establish their nest in a given location. Specific objectives of this research are: 1) to examine the population dynamics and nesting habits of ground-nesting bees; 2) to determine the impact of pesticides in soil on ground-nesting bees, particularly in the context of combatting the blueberry maggot and spotted wing drosophila in Quebec's Lac-St-Jean region; and 3) to test various habitat enhancement strategies in order to increase the abundance of ground-nesting bees. For each of these specific objectives, particular attention will be paid to the blueberry specialist Andrena carolina. Scientific approaches will consist of in-field manipulations using emergence traps and in-situ assays. Understanding the characteristics that make a location suitable or not for nesting has important management implications, such as enhancing farm practices or landscape to favour ground-nesting bees. We aim to provide a much-needed quantitative and comparative analysis of nesting site selection for a whole community of ground-nesting bees in an agroecosystem. This will enable us to provide growers with new tools and policies to enhance their on-farm wild bee communities, thus increasing wild bee biodiversity, ensuring pollination services autonomy and reducing dependence on rented honey bee hives.