D3059: How do fungicides and pesticides influence bee's susceptibility to parasitic infections?

Some of the most abundant pesticides found in bee products are fungicides, which were once thought of as less toxic toward insects compared to other pesticides. For example, among 24 other predictors, fungicide usage was the strongest predictor for bumble bee colony failure, especially in declining species.

In the local apple orchards in New York state, wild bee abundance and diversity are strongly impacted by the usage of fungicide especially before and during bloom. Pesticide exposure in these orchards can be intense. Toxicology surveys across 23 states during 2007 - 2008 growing season showed 121 types of pesticide/metabolites compounds were found from 887 wax, pollen, bee, and hive related samples.

Because exposure to multiple insecticides and fungicides is likely to make wild bees more vulnerable to parasites and pathogens, I hypothesize that infection prevalence will correspond to insecticide/fungicide exposure. I predict that samples from orchards that are exposed to insecticide/fungicide during blooms will have a higher infection prevalence. I also predict the type of infection will correspond to the historical relationship between pathogen and host species. So far, our pesticide preliminary data from 30 apple orchards showed that difenoconazole, cyprodinil, trifloxystrobin, metolachlor, and atrazine are ubiquitous in honeybee pollen, bumblebee wax, and mason bee pollen while tebuthiuron presents in honeybee pollen, honeybee nectar, and bumblebee wax but not in mason bee pollen.