Did northern corn rootworms lay eggs in soybeans?
During the summer of 2005, adult northern corn rootworms were abundant throughout Iowa. They were common in gardens during the midsummer, they frequented lights around buildings at night, and they were still common on early fall flowers such as thistle. But most surprising was the frequency at which large numbers were found in soybean fields. This apparent increase in corn rootworms has created questions concerning the potential for injury, especially to rotated corn. With the spread of the extended-diapause northern corn rootworm (Diabrotica barberi) throughout Iowa, some of the concerns are justified. Our intensive, annual rotation of corn with soybeans has resulted in the selection of a northern corn rootworm strain that has a two-year life cycle. Some eggs laid in corn don’t hatch the following growing season, but remain in diapause (a state of dormancy) throughout another summer and winter to hatch when corn is planted in the field nearly two years later (but see the exception bel
