Posted: June 16, 2017

Neonicotinoids and honey bee health

Beneficial insects can be affected by neonicotinoids.

Neonicotinoids--the most widely used class of insecticides--significantly reduce populations of beneficial predatory insects when used as seed coatings, according to researchers in the college. The team's research challenges the previously held belief that neonicotinoid seed coatings have little to no effect on predatory insect populations.

"Beneficial predatory insects contribute billions of dollars a year to agriculture through the elimination of crop pest insects," says Margaret Douglas, postdoctoral researcher in entomology at Penn State. "We have found that neonicotinoid seed coatings reduce populations of these natural enemies 10 to 20 percent."

According to John Tooker, associate professor of entomology at Penn State, the use of neonicotinoids has risen dramatically in recent years, especially for large-acreage crop species like corn, soybeans, and cotton. The insecticide is most often applied to seeds as a prophylactic coating. When the seeds are planted, the insecticide enters the soil where some of it is taken up by plant roots. The chemical then runs systemically through the plant, protecting young seedlings from insect pests. The results appear in the online journal PeerJ.

Honey bee health may be curbed by a common chemical.

A chemical thought to be safe, and therefore widely used on crops--such as almonds, wine grapes, and tree fruits--to boost the performance of pesticides, makes honey bee larvae significantly more susceptible to a deadly virus, according to Chris Mullin, professor of entomology, and colleagues. This finding is described in the January 16 issue of Scientific Reports.

"In the lab, we found that the commonly used organosilicone adjuvant Sylgard 309 negatively impacts the health of honey bee larvae by increasing their susceptibility to a common bee pathogen, the Black Queen Cell Virus," says Julia Fine, a graduate student in entomology.

--Sara LaJeunesse