Damage of Diabrotica virgifera to maize following soybean in USA
In late June 1987, severe damage caused by larvae of Diabrotica virgifera (EPPO A2 quarantine pest) were observed on maize grown for seed production, in Illinois (USA). This damage occurred in 6 fields which had been planted the year before with soybeans. These soybean crops were free from weeds and grown for seed production. Damage in first year maize crops was observed again in the same area in 1988 and to varying degrees during the following years. Laboratory studies and field studies were conducted to try to explain the possible causes of this new problem. Results demonstrated that eggs of D. virgifera from populations found in this area did not present a prolonged diapause trait (i.e. eggs which could enter into diapause for 2 winters or more). Field studies showed that a small number of D. virgifera eggs were laid in soybean fields. It was noted that pyrethroid insecticides are routinely used in maize crops grown for seed production to control Helicoverpa zea. In the laboratory, it was demonstrated that permethrin acted as a repellent for D. virgifera females. The authors felt that the use of permethrin in maize fields probably incite females to lay eggs in untreated soybeans situated nearby. They concluded that the occurrence of damage on first year maize following soybean is probably due to the use of pyrethroid during the previous summer in adjacent maize fields.
Levine, E.; Oloumi-Sadeghi, H. (1996) Western corn rootworm (Coleoptera: Chrysomelidae) larval injury to corn grown for seed production following soybeans grown for seed production.
Journal of Economic Entomology, 89(4), 1010-1016.