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Over 70 per cent of wild bee species, crucial for pollinating food crops, face alarming risks from pesticide residues in soil, a new study has revealed.
The research highlighted that the current regulations and pesticide risk assessments fail to account for the impacts on wild bees and one of the reasons for that was the reliance on the western honey bee (Apis mellifera), by pesticide regulatory authorities worldwide, as the model species to assess risks to all bees.
“This specific focus is problematic owing to substantial differences in life history traits, exposure routes and vulnerabilities among bee species. For example, whereas most of the world’s over 20,000 bee species are solitary, honey bees live in large colonies that benefit from social detoxification strategies, which buffer pesticide impacts,” said the study’s lead author Sabrina Rondeau, a Natural Sciences and Engineering Research Council of Canada postdoctoral fellow in the department of biology at the University of Ottawa.
Current pesticide environmental risk assessments overlook soil pesticide residues as a threat to pollinators because honey bees rarely interact with soil. In contrast, over 80 per cent of bee species nest or overwinter underground, which exposes them to these residues, the study found.
“The very pesticides designed to protect our crops endanger essential pollinators that sustain their productivity,” said Rondeau.
The study, Digging below the surface: Hidden risks for ground-nesting bees, published in the journal Science, used two agriculturally relevant model species: The common eastern bumble bee, Bombus impatiens, and the hoary squash bee, Xenoglossa pruinose, to study wild ground-dwelling bees.
It aimed to find out if bumble bee queens can detect and avoid pesticide-contaminated soils, or whether they might be attracted to them and it was found that they were seemingly attracted to pesticide-contaminated soils.
“This apparent preference increases their likelihood of exposure to and potential risk from pesticide residues while they overwinter underground,” the study revealed.
Further, it also found that exposure to certain pesticides in soil, particularly cyantraniliprole, used to control a variety of pests on crops, reduced survival and reproductive success in bumble bee queens, potentially impacting future generations.