Characterization of a novel activity for western corn rootworm (Diabrotica virgifera virgifera) management

Improved strategies for management of western corn rootworm (WCR), Diabrotica virgifera virgifera, including transgenic technology would be highly beneficial for crop protection. To obtain protein toxins with novel activity against WCR, we surveyed microbial cultures using a high throughput in vitro WCR bioassay. Cultures from strain 182-05 tested in these assays resulted in significant activity against WCR. The activity from 182-05 was located in the culture supernatant and found to be heat sensitive. Culture supernatants from 182-05 were fractionated by anion exchange chromatography and WCR active fractions were obtained. The active component(s) in these fractions resulted in 100% mortality of WCR in our in vitro assays. Partially purified material from the anion exchange column was further fractionated on gel filtration columns and the activity eluted in the 10-15kD size range. The active material from the gel filtration column was found to be heat sensitive but resistant to proteases suggesting that the active component(s) are non proteinaceous small molecules. Further characterization of these WCR active molecules could enable the development of a method for control of these pests in the fields.