Journal of Economic Entomology (2004) 97, 2095-2100

Bahagiawati Amirhusin, Richard E. Shade, Hisashi Koiwa, Paul M. Hasegawa, Ray A. Bressan, Larry L. Murdock and Keyan Zhu-Salzman (2004)
Soyacystatin N inhibits proteolysis of wheat alpha-amylase inhibitor and potentiates toxicity against cowpea weevil
Journal of Economic Entomology 97 (6), 2095-2100
Abstract: Genetic engineering may be used to introduce multiple insect resistance genes with different modes of action into crop plants. We explored the possible interactions of two differing gene products fed in the diet of cowpea weevil, Callosobruchus maculatus (F.), a stored grain pest. The soybean cysteine protease inhibitor soyacystatin N (scN) and alpha-amylase inhibitor (alphaAI) from wheat have defensive function against this coleopteran. When artificial seeds containing both scN and alpha(AI) were infested with eggs of C. maculatus, the delays in larval development were longer than was predicted by summing the developmental delays seen when larvae were fed a diet containing the individual proteins, indicating that the effects of scN and alpha(AI) are synergistic. alpha(AI) was readily hydrolyzed when incubated with insect gut extract. This proteolytic degradation was inhibited by scN, but not by Kunitz inhibitor (a serine protease inhibitor). Thus, degradation of alpha(AI) was due to proteolysis by insect digestive cysteine proteases. These data suggest that C. maculatus uses digestive enzymes not only to function in food protein digestion but also to defend the insects themselves by helping reduce the concentration of a toxic dietary protein.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Richard E. Shade, Larry L. Murdock

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Callosobruchus maculatus