Effect of food and temperature on the development and silk production of Bombyx mori Linnaeus (Lepidoptera: Bombycidae).

Abstract

Larvae of Bambyx mari Linnaeus were reared on food of different qualities at different temperatures. - It was found that although the rate of development was highest at 30°C and lowest at 20°C, mature larvae and pupae weighed more at 25°C. Water content of pupae reared at 20°C was higher than that at the other two temperatures. Larvae reared on leaves from seedling varieties of mulbeny developed more quickly than those reared on leaves from grafted varieties. The pupal period, however, was longer on the former than on the latter food. The lower rate of larval development on grafted varieties was associated with decreased larval and pupal weights. Irrespective of temperature and quality of food, larvae and pupae of females were always heavier than those of males. The rate of survival among caterpillars was lower at 30°C than at 20°C or 25°C. It was also lower on grafted M. alba than on any other food. Silk production by caterpillars was highest at 25°C and lowest at 30°C. When larvae were reared on leaves from seedling varieties of mulberry, they produced more silk than those reared on leaves from graf ted varieties. Female caterpillars always produced heavier green cocoons than males. Silk shells from heavier female cocoons, however, did not weigh more chan those from lighter male cocoons, except at the unfavourable temperature of 30°C on seedling foods. Insects laid the highest number of eggs when reared at 25°C and the smallest number at 30°C. There was no difference in larval and pupal weights at 20°C and 30°C, but lower fecundity at 30°C than at 20°C was definitely associated with the fact that the life of the moths was shorter at the former than at the latter temperature. Insects reared on leaves from seedling mulberry laid significantly more eggs than those reared on leaves from grafted varieties. Adult life was shorter on grafted M. alba than on any other food. Generally the males lived longer than the females.