Using Insecticides that Conserve Good Bugs

On this page, you will find a summary and detail for recent research projects by Principal Investigator, Dr. Vera Krischik, and her research staff on beneficial insect and pollinator conservation including biocontrol, land management best practices, and pesticide effects on pollinators and beneficial insects.

Effects of Chronic Insecticide Exposure on Bumblebees

Declines in bee populations around the world have been attributed to various factors, one of which is pesticide use. The purpose of this project was to examine the toxicity of several insecticides to bumble bees (Bombus impatiens). We found that chlorantraniliprole (4 ppm), an insecticide commonly used for Japanese beetle control, was less toxic to bees than the neonicotinoid clothianidin (0.02 ppm). Also, clothianidin resulted in a decrease in brood production and movement. 

Published:  Scholer, J. and V. Krischik. 2014. Chronic exposure of imidacloprid and clothianidin reduce queen survival, foraging, and nectar storing in colonies of Bombus impatiens. PLoS ONE 9(3): e91573. doi:10.1371/journal.pone.0091573

Summary:  Papers on sublethal effects of neonicotinoid insecticides on native bee behavior, compiled by Krischik Lab, 2020.

Effects of Acute Insecticide Exposure on Butterflies

The purpose of this study was to examine the lethal effects of four insecticides on monarch butterflies (Danaus plexippus) and painted lady butterflies (Vanessa cardui). Acute exposure bioassays were carried out to determine LC50 values for monarch and painted lady larvae exposed to bifenthrin (pyrethroid), chlorantraniliprole (ryanoid), clothianidin (neonicotinoid), and imidacloprid (neonicotinoid), and painted lady adults exposed to clothianidin. We found that chlorantraniliprole was the most toxic insecticide for both species; for monarch larvae, the LC50 for chlorantraniliprole was 5-20x lower than that of the other insecticides, while for painted lady larvae it was 20-9000x lower. Additionally, although painted lady larvae were more sensitive than monarchs to chlorantraniliprole, monarch larvae were substantially more sensitive to the other three insecticides.

Effects of Chronic Insecticide Exposure on Butterflies

Chronic exposure bioassays were carried out to evaluate sublethal effects of clothianidin (neonicotinoid) on monarch (Danaus plexippus) and painted lady (Vanessa cardui) butterflies. Butterfly larvae were fed treated (0-40 ppb) foliage from third instar to pupation. We found that 40 ppb clothianidin significantly reduced the number of larvae that pupate for both monarchs and painted ladies. In addition, 40 ppb clothianidin resulted in greater mean days to pupation for monarch larvae, while there was no significant effect for painted lady larvae.

Pesticide Residues in Wildflowers Near Crops

Pesticide drift from agricultural applications can be a source of harmful pesticide exposure for pollinators. In this project, we sampled wildflowers on the margins of potato, soybean, and corn fields. For wildflower samples collected on habitat near potato fields in MN, we found that 100% of 36 samples had at least one pesticide and as many as 15 different pesticides.