Tuesday, March 22, 2016

U of MN researchers seeking soybean growers to cooperate on study of impacts of seed treatments on soybean aphid and parasitic wasps

by Jonathan Dregni (Scientist), Robert Koch (Assistant Professor & Extension Entomologist), and George Heimpel (Professor)

Insecticidal seed treatments are used widely in soybean production. As with any new pest control technology we need to examine the potential for unintended consequences (see more at 
The Effectiveness of Neonicotinoid Seed Treatments in Soybean). University of Minnesota entomologists are looking for farmer collaborators willing to help study insecticidal seed treatments by allowing researchers to monitor populations of aphids and parasitic wasps in soybean fields planted with insecticide-treated and untreated seeds. Please contact Jonathan Dregni, U of MN scientist, if you or a neighbor would like to be involved, dreg0005@umn.edu or 651-207-3539.

Parasitic wasps are an important part of aphid pest control, because they feed on aphids and only on aphids. These tiny, stingless wasps pose no risk to humans or livestock, and no risk to anything other than aphids. Parasitic wasps are imported for biological control programs to reduce pest insects and current regulations require years of research to ensure the risks of adverse consequences are minimal. By monitoring wasps and aphids in treated and untreated fields, researchers will learn about their seasonal population patterns and the effect of insecticide seed treatments on the natural enemies of aphids.

Adult female parasitic wasps inject eggs inside aphids. Larvae that hatch from the eggs devour the aphids from within, and then make cocoons inside the dead aphids, which are called aphid “mummies.” The next generation of adult wasps emerges from these tan to black mummies. When managing soybean aphid, use of scouting and the economic threshold (250 aphids per plant) will help reduce insecticide inputs and conserve these aphid-killing wasps.

In 2005 a very successful parasitoid of soybean aphid was found in North America and by 2011 this Asian wasp, Aphelinus certus, was found in Minnesota. Near the Twin Cities we have studied and released a close relative, Aphelinus glycinis, in a biological control program with the hopes of providing better aphid control with fewer ecological concerns. Finally a third parasitic wasp, Lysiphlebus testaceipes, which is a North American native species, has begun feeding on soybean aphid. To determine the extent of these and other parasitic wasp species in different regions of Minnesota, scientists at the University of Minnesota and Minnesota Department of Agriculture continue to conduct surveys throughout the region (find more here).