Vicilins (7S storage globulins) of cowpea (Vigna unguiculata) seeds bind to chitinous structures of the midgut of Callosobruchus maculatus (Coleoptera : Bruchidae) larvae

The presence of chitin in midgut structures of Callosobruchus maculatus lar vae was shown by chemical and immunocytochemical methods. Detection by West ern blotting of cowpea (Vigna unguiculata) seed vicilins (7S storage protei ns) bound to these structures suggested that C, maculatus-susceptible vicil ins presented less staining when compared to C. maculatus-resistant vicilin s. Storage proteins present in the microvilli in the larval midgut of the b ruchid were recognized by immunolabeling of vicilins in the appropriate sec tions with immunogold conjugates. These labeling sites coincided with the s ites labeled by an anti-chitin antibody. These results, taken together with those previously published showing that the lower rates of hydrolysis of v ariant vicilins from C, maculatus-resistant seeds by the insect's midgut pr oteinases and those showing that vicilins bind to chitin matrices, may expl ain the detrimental effects of variant vicilins on the development of C. ma culatus larvae.