MANHATTAN -- Examining if and how corn borer resistance to Bacillus thuringiensis (Bt) toxins develop so farmer-friendly resistance management plans can be identified, is the focus of a genetic study done by a team of entomology researchers at Kansas State University. Their findings appear in the May 7 issue of Science, the weekly journal of the American Association for the Advancement of Science.
In the past, pests such as the European and Southwestern corn borers have inflicted hundreds of millions of dollars worth of damage to crops. Farmers were forced to either chemically spray the pests with insecticides or suffer the losses. A current method for combating pests like these corn borer is to genetically engineer maize and other crops to produce a toxin inside the plant that will kill them.
The method is safe, with no harm to the environment and the economic return can be enormous in years when these pest populations are high, provided the pests do not develop resistance to the toxin.
Randall Higgins, a research entomologist with K-State research and extension; Fangneng Huang, a research associate and post-doctoral student; Larry Buschman, a research entomologist; and William McGaughey, a professor emeritus of entomology, say the strategy for this resistance plan hinges on several assumptions, one being that the genes that make the borer resistant to the toxin are recessive. When these pests reproduce, their offspring must inherit the resistant gene from both parents to be able to survive exposure to the toxin.
In lab studies where the researchers mixed certain forms of the Bt toxin into the pests' diet, the European corn borers' resistance appears to be inherited as an incompletely dominant trait. Higgins said, though somewhat surprising, this does not mean this borer will exhibit resistance dominance to toxin genes inserted into transgenic corn in the field.
"The Bt toxins that we used are not identical to the material expressed in
'"/>
Contact: Randall Higgins
rah@ksu.edu
785-532-6154
Kansas State University
7-May-1999