A body of evidence from over 100 individual experiments included in 23 combined studies reveals that pesticides are dumbing down bees. A new study analyzed years of bee evidence and found 23 studies related to bees and pesticides. The studies showed that even if pesticides are not killing bees, they may still negatively impact bee colony health and survival.
Bees require a high degree of intelligence to navigate and discover the most effective routes to forage food and bring it back to the colony. The changing nature of weather and seasons means bees need to be able to use learning and memory skills to re-establish foraging routes, Popular Science writes. Bees can even memorize which plants they have already visited so that they don’t waste time revisiting the same flower.
Pesticides Negatively Impact Bee Intelligence
In the experiments, lab scientists exposed bees to equivalents of pesticide doses they might come across in the natural world. Regardless of whether the bees were exposed to large levels of pesticides all at once or little doses over a long period, pesticides “had significant negative effects on learning and memory.” The results were the same whether the bees were exposed to neonicotinoids, a pesticide more regulated in recent years, or other pesticides.
Pesticide use is currently regulated to protect against lethal dosage levels. However, the study shows that sublethal pesticide exposure could still be negatively affecting bee colony health by reducing their ability to find food. This finding could reflect an important and necessary shift needed in animal conservation towards acknowledging the importance of sublethal doses of chemicals on animals.
“Regulation and policy should move toward addressing the sub-lethal effects of pesticides,” said study author Harry Siviter, a graduate student at the Royal Holloway University of London.
Can Pesticides Be Used Safely Around Bees?
While the study focused on bee colony health, it didn’t take into account the effect of pesticides on other types of bees. According to Guelph scientist Elizabeth Bates, many wild bees live solo, and pesticide exposure may be even more harmful to them.
“Many wild bees do not live in colonies,” she says, “and if their learning or memory are affected, there are no other bees to help out or pick up the slack.”
Ohio State University entomologist Reed Johnson and University of Ottawa bee conservationist Jeremy Kerr warned Popular Science that the effects of pesticides on bees need to be taken seriously.
“Can pesticides ever be used safely around bees?” This study “suggests that the answer is ‘no,’” Johnson wrote.
“The lesson that emerges is that honeybees begin to lose their ability to learn and to remember when they are exposed to neonicotinoids,” Kerr told Popular Science.
When a third of the U.S.’ honeybee population died between April 2016 and April 2017, understanding pesticide exposure on bees is paramount in combatting the decade-long decline of the bee population.