Bumblebee Queen shows the complex effects of pesticide exposure on pollinator health

According to a team of researchers at Pennsylvania’s Agricultural Sciences, a team of researchers from the University of Agricultural Sciences, which recently published an article on the topic of biology, the effects of pesticide exposure on pollinator health were initially considered. It can be more complicated than it was.

In this study, the researchers examined the effects of imidacloprid, a common insecticide, on bumblebees. They found that pesticide exposure is associated with shorter lifespans and reduced reproduction, while lower doses are also associated with new queens who survive longer at dormant.

This phenomenon of homosis is well understood when low doses of fatal toxins actually benefit insects, according to Etia Amsalem, an associate professor of entomology at Pennsylvania State University and its lead author. These short-term benefits are often at a cost. About the research.

“If homosis is not recognized, it could lead to the false conclusion that certain pesticides will benefit honeybees,” Amsalem said. “This misconception is dangerous given the trade-offs between the short-term profits with long-term fitness, given the well-documented negative effects of imidacloprid and the trade-offs associated with hormonal responses.”

Amsalem added that a useful analogy for formosis is caffeine. Smaller doses can be beneficial, but higher doses can be toxic.

“Even low doses can have unintended effects, such as destroying sleep,” she said. “Just as coffee drinkers should recognize multiple effects, researchers and policymakers must explain formosis when assessing the effects of pesticides to pollinators.”

Researchers say that Pennsylvania’s native Bumblebee Queen is particularly vulnerable to external pressures, such as severe winters. Bumblebee Queens need to survive until spring when they can start new colonies, in a dormant stage that allows insects to withstand harsh environmental conditions.

Over 75% of the Queen Bumblebee’s lifespan can be spent dormant. This is a considerable amount of time when honeybees face extreme temperatures, infections, and starvation. And if she does not survive this period, she will not be able to establish a new colony of bumblebees. This means that the world could lose up to hundreds of potential pollinators in all dying queens.

“But dormancy is not very understood,” Amsalem said. “And despite the fact that most pollinators are in winter dormant, pesticide risk assessments usually focus on the active seasons of bees and overlook a significant portion of the bee life cycle. It’s there.”

During active seasons, pesticides are known to have harmful effects on pollinators, Amsalem said. Many pesticides are soluble in water. There, plants can absorb and transport them to pollen and nectar. When this occurs, pesticide residues can be picked up by beneficial insects, such as honeybees and other pollinators. This pesticide exposure can cause immediate death or reduced life expectancy and may not be able to reproduce.

To assess the effects of imidacloprid, one of the most widely used neonicotinoid pesticides, in both active seasons and dormant, researchers mixed imidacloprid with sugar water and ingested the solution . The total life expectancy of men, workers and queens was then assessed and the female reproductive output was measured.

“The results were simple. The higher the concentration, the shorter the lifespan and the less typical and expected responses of honeybees to neonicotinoids,” Amsalem said. .

Amsalem said that what came next was a little more surprising.

“In the second experiment, it was fed to Queen’s Sabrasa concentrations of imidacloprid, which was then placed in refrigerated storage to induce dormancy and monitor survival weekly,” she said. “Amazingly, we found that subtal imidacloprid exposure actually improves Queens’ survival.”

Researchers found that these queens were unexpectedly resilient to harsh winter conditions after pesticide exposure.

Amsalem recommended that these findings be integrated into bumblebee risk assessment and conservation management strategies. She also argued that further studies of these hormonal responses would be necessary to assess why these reactions occurred. Knowing the mechanisms may give scientists a more broad understanding of insect responses to pesticides, she said.

“Most importantly, we must strive to implement subtle science that provides a holistic understanding of how stressors affect pollinators.

The paper was co-authors of postdoctoral scholar Nathan Delstyn and Pennsylvania undergraduate research assistant, Cameron Murray.