“No Pollinator is Safe”—New Evidence of Neonicotinoids Harming Wild, Ground Nesting Bees

April 13, 2021 | A study is making it increasingly clear that current laws are not protecting wild, ground nesting bees from the hazards of neonicotinoid insecticides. According to research conducted under a grant from the U.S. Department of Agriculture’s Sustainable Agriculture Research and Education (SARE) projects, Blue Orchard Mason Bees (Osima spp) are at particular risk from pesticide-contaminated soil they use to create their nest. Authors of the study note that with honeybees already in decline, pollination services provided by wild managed bees like Mason bees are growing in importance. “Wild bees such as Osmia are becoming increasingly popular as managed pollinators in many systems, as there is growing concern that honeybees may not be able to continue to meet the increasing demands of agricultural pollination if these trends continue,” the study reads. The study found no trend to the mason bee’s ability to distinguish between contaminated and uncontaminated soil. Embryos appeared to be resilient to the effects of pesticide exposure. However, female mason bees were harmed by soil contact exposure, with effects on fitness noted at each exposure level. At the highest exposure rate, researchers observed a 66% decline in nesting activity as females produced 40% fewer offspring overall. Nesting activity was similarly reduced by 42% in the medium exposed group. For the lowest exposures at 50 ppb (the equivalent of adding 50 drops of pesticide in a 10,000 gallon swimming pool), the sex ratio for offspring was skewed toward male bees. This group had 50% fewer female bees than the unexposed control group. [Fortuin, Christine. Effects of Imidacloprid Soil Drench Applications on Nesting Blue Orchard Mason Bees (Osmia lignaria). Sustainable Agriculture and Education Projects, 2021.]