Credit: Ian Grettenberger

An insecticide banned in some areas for its effect on bees not only fails to kill certain pests, but also harms the predators that feed on them.

Neonicotinoid insecticides are used on many crops, including soya-bean plants, on which pest slugs (Deroceras reticulatum) feed. Margaret Douglas at the Pennsylvania State University in University Park and her colleagues exposed the slugs in the lab to soya-bean plants grown from seeds coated with the neonicotinoid thiamethoxam. They found that the slugs were unaffected, but that more than 60% of ground beetles (Chlaenius tricolor, pictured), which feed on the slugs, died or suffered impairments such as paralysis. In field studies, thiamethoxam also lowered the number of predators on slugs, and reduced soya-bean yields by 5%.

The results indicate unintended indirect effects of neonicotinoids on non-target species in addition to known direct effects, the authors say.

J. Appl. Ecol. http://doi.org/xqr (2014)