Determination of Key Mortality Factor of Mexican Beetle, Zygogramma Bicolorata Pallister

Life tables were constructed under Delhi conditions for Zygogramma bicolorata in order to determine the key mortality factor acting on the species. The pupal stage was found to be the key mortality stage that contributed most to the overall mortality followed by egg stage. Pupal malformation, failure to lay eggs and infertility were prominent mortality factors. The main cause of mortality of older larvae was their inability to burrow into hard and dry soil for pupation. Besides, weather factors in general were found to have an effect on all developmental stages of Z. bicolorata. The sex ratio was biased towards females with their proportion being 0.6-0.7. The generation trend index was very high (272.21) during July followed by October (231.07) and August (199.40). The generation mortality was low during June-October while it was high during January, May and December.