Abstract

Two semi-synthetic diets were studied with reference to their effect on the develo pment of the pro-imaginal stages of gram pod borer, Heliothis armigera. Incubation period was not at all influenced while the larval period was found to be reduced by 50 to 60 per cent from that on lab-lab. The number of instars in the larval stage was reduced to five in the second generation on diet-A, while in the others it was only six in both the generations. Increase in length and weight of larvae was evidenced conso- quent to intake of semi-synthetic diet. While the prepupal period was shorter on natural hosts, the total period was markedly shorter and pupal weight distinctly greater on arti- ficial diets. The total life-cycle as such was also found to be shortened, especially in the second generation in all the diets.

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