Insecticides aimed at controlling early-season crop pests, such as soil-dwelling grubs and maggots, can increase slug populations, thus reducing crop yields, according to researchers at Penn State and the University of South Florida.
“Neonicotinoids are the most widely used insecticides in the world,” said Margaret Douglas, graduate student in entomology, Penn State. “Seed applications of neonicotinoids are often viewed as cheap insurance against pest problems, but our results suggest that they can sometimes worsen pest problems and should be used with care.”
According to John Tooker, associate professor of entomology, Penn State, recent research links neonicotinoids with negative effects on pollinators and pollution of surface water in agricultural ecosystems, and even with cascading negative effects on aquatic invertebrates and insect-eating birds. However, the effects of these common seed-applied insecticides on soil-dwelling creatures have been little explored.
“Our research suggests that neonicotinoids can have unintended costs, even within crop production,” he said.
The researchers conducted laboratory and field experiments. In the lab, they exposed slugs to three types of soybeans — untreated soybeans, soybeans whose seeds were treated with fungicide, and soybeans treated with fungicide and seed-applied thiamethoxam, a very common neonicotinoid. The team then tracked slug weight and survival. Next, the scientists presented slugs from the treatments to a ground beetle species that eats slugs. They then tracked slug mortality and symptoms of beetle poisoning. Continue reading “Insecticides foster ‘toxic’ slugs, reduce crop yields”