https://www.eurekalert.org/pub_releases/2021-02/uoc--pto022621.php
News Release 26-Feb-2021
University of Guelph
An insecticide used to control pest infestations on squash and pumpkins significantly hinders the reproduction of ground-nesting bees -- valuable pollinators for many food crops, a new University of Guelph study has revealed.
This first-ever study of pesticide impacts on a ground-nesting bee in a real-world context found female hoary squash bees exposed to imidacloprid dug 85 per cent fewer nests, collected less pollen from crop flowers and produced 89 per cent fewer offspring than unexposed bees.
"Because they're not making nests and not collecting pollen, they cannot raise offspring," said Dr. Susan Willis Chan, a post-doc in the School of Environmental Sciences (SES), who conducted the study with Dr. Nigel Raine, holder of the Rebanks Family Chair in Pollinator Conservation in SES. "That means imidacloprid-exposed populations are going to decline."
Neonicotinoids (or neonics) are neurotoxic insecticides that kill insects by attacking their nervous systems, affecting learning, foraging and navigation in many kinds of bees. Farmers use the neonic imidacloprid to control cucumber beetles, the most damaging crop pest for squash and pumpkins.
Many species of ground-nesting bees, including the hoary squash bee, are responsible for pollination of numerous fruits, vegetables and oilseed crops in North America, said Chan.
"Solitary ground-nesting bees make up about 70 per cent of bee species. It's a really important ecological group and is also really important in crop pollination," she said.
However, these ground-dwellers are often overlooked when it comes to evaluating the impacts of pesticides on pollinators, she added.
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