Genes Foil Hessian Flies' Feeding on Wheat
Comis April 5, 2007
Resistant wheat varieties are known to stress Hessian fly
(Mayetiola destructor) larvae to death within six days. How this happens
is a mystery researchers need to solve to better control the most destructive
pest of wheat worldwide.
The recent identification by Agricultural Research Service (ARS) scientists and cooperators of six
antioxidant genes in Hessian fly larvae is a step toward solving this mystery.
The antioxidants produced by these genes help prevent oxidative damage to the
larvae's cell membranes from peroxides, which can be produced both by the wheat
plant and by the stresses the larvae suffer.
Shukle, an entomologist in the ARS
Production and Pest Control Research Unit at West Lafayette, Ind., and
Purdue University entomologists Omprakash
Mittapalli and Jonathan Neal identified these genes. They found that the genes
produce more antioxidants in larvae trying to feed on resistant wheat plants
than in larvae feeding on non-resistant wheat plants. The increase in
protective antioxidants is an indicator of stress, and too great a level of
stress may kill the larvae.
The stress could be caused by a one-two punch to the larvae. The first
blow might be the peroxide poisons that resistant wheat plants emit in their
juice, or sap--if larvae are able to extract it. The second blow could be the
starvation that results if the larvae fail to extract sap from resistant
plants. The only thing for certain is that the masses of larvae failing to feed
on resistant wheats soon weaken and die at the base of the plants.
Understanding all the ways that resistant wheat plants stress out
Hessian fly larvae should also help scientists better control other insect
pests of other crops. This is because peroxides and other toxic oxygen
compounds are used by many plants in defending against insects that hunger for
A paper on this study was published in February in the journal Proceedings of the National Academy of
ARS is the U.S. Department of
Agriculture's chief in-house scientific research agency.