Adding to growing evidence that pesticide use may be contributing to the decline of many bumblebee species across North America, a new study reveals that daily consumption of even small doses of a widely used class of insecticides known as neonicotinoids reduces the survival of queen and male bees, which are critical to the survival of wild populations. The study also found that exposure to the chemicals alters the expression of genes regulating biological functions such as locomotion, reproduction, immunity, and learning and memory, suggesting that neonicotinoids may be having a greater negative impact on the viability of wild bumblebee populations than previously thought.
The study (“One size does not fit all: Caste and sex differences in the response of bumblebees (Bombus impatiens) to chronic oral neonicotinoid exposure”), by Robert J. Gegear, assistant professor of biology and biotechnology at Worcester Polytechnic Institute (WPI), and Melissa Mobley '17 (PhD) (who worked on the research as a PhD candidate), was published in the open-access journal PLOS ONE. It is the first study to examine how oral exposure to field-realistic doses of neonicotinoids differentially affects queen, male, and worker bees at the individual level. Since each type of bee makes a separate, but vital, contribution to the stability of wild populations, understanding how each responds to neonicotinoids can help establish agricultural practices and regulations that can better protect native bees and other pollinators and preserve the critical role they play in maintaining ecosystem function and biodiversity, Gegear said.
“There are approximately 4,000 bee species native to North America,” he noted, “and many are in rapid decline. For example two of the 10 bumblebee species that were historically present in Massachusetts are now gone and a few more are headed in the same direction. As our bumblebees and other native pollinators disappear, so too will our native flowering plants and the animals that use them for food, shelter, and nesting sites.