The cysteine protease inhibitor soyacystatin (scN), a defense protein from soybean, negatively impacts growth and development of the cowpea bruchid, Callosobruchus maculatus [Koiwa et al. (1998) Plant J. 14: 371-379]. Continuous monitoring of the feeding behavior of the bruchids reared on artificial cowpea seeds with a relatively low dose of scN incorporated indicated that developmental delay and feeding inhibition caused by dietary scN occurred during the early developmental stages of cowpea bruchid, as the 4th instar larvae reared on scN-incorporated artificial seeds showed feeding and development comparable to those reared on control artificial seeds. To uncover insect countermeasures against such plant defense proteins, we examined the involvement of cysteine proteases in cowpea bruchid protein digestion, the differential regulation of the target proteases by dietary scN, and their possible functions in minimizing the effect of scN. Our results indicate that qualitative and quantitative modulation of cysteine protease genes, as well as hydrolysis of plant defensive proteins, are strategies utilized by cowpea bruchids to cope with plant defense.
Species 1: Coleoptera Bruchidae Callosobruchus maculatus (cowpea bruchid)
Keywords: counter defense, gene regulation
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