VOLATILES EMITTED BY DIFFERENT COTTON VARIETIES DAMAGED BY FEEDING BEET ARMYWORM LARVAE

Volatile compounds elicited by insect herbivore feeding damage in five cotton cultivars and one naturalized cotton variety were examined by allowing beet armyworm larvae to feed overnight on leaves and collecti ng volatiles from the plants in situ. Of 23 compounds identified from larval damaged leaves, terpenes and lipoxygenase-hydroperoxide lyase-d erived volatiles predominated. No pronounced differences in the levels of volatile emission were noted from leaves of undamaged plants of th e different varieties. However, average volatile emission from damaged leaves of the naturalized variety was almost sevenfold higher than fr om damaged leaves of the commercial cultivars. This was despite the fa ct that larvae preferred feeding on the leaves of commercial cultivars over those of the naturalized variety in choice tests.