EFFECT OF DIFFERENT FOOD LEAVES ON REARING PERFORMANCE IN INDIAN TROPICAL TASAR SILKWORM, ANTHERAEA MYLITTA DRURY (LEPIDOPTERA : SATURNIIDAE)

摘要

An attempt was made to rear the ecorace Daba (Bivoltine, domesticated) of tropical tasar silkworm (Antheraea mylitta D) on leaves of Terminalia tomentosa W&A, Lagerstroemia parviflora Roxb. and in their combinations to evaluate the food associated traits. The larval span (days), spinning period (h) were lowest if the caterpillars were fed on T. tomentosa. The effective rate of rearing per cent, cocoon yield/dfl, Single Cocoon Weight (g), Single Shell Weight (g) and absolute silk yield (g) remained significantly higher on T. tomentosa over L. parviflora and its combinations with T. tomentosa. The productivity of cocoons from a single disease free laying remained 36.60 cocoons on L. parviflora. However, there was no difference in the yield/dfl if thecaterpillars are reared on F_2 (L. parviflora) and F_3 (rearing on T. tomentosa upto 3rd stage and subsequent rearing on L. parviflora from 4th to 5th stage). The yield on L. parviflora can be increased if this food plant is used in the middle of fifth instar of larvae after five days of fifth instar feeding on T. tomentosa (F5), with 45.2 cocoons and 52.800 grams of absolute silk from a single disease free laying. The relation between independent associate cocoon weight (g) with dependent associate shell weight (g) was significant (P<0.05, df 13) in all the food combinations except F3 i.e. rearing on T. tomentosa up to 3rd stage and subsequent rearing on L. parviflora from 4th to 5th stages (P>0.05 df: 13). Food in combinations of F2 and F4 presentedpositive association of the shells with their cocoons. However, there was a negative intercept in F2 and F_4 in the regression function. Thus, the association of a combination of feed empowered the silk insect larvae to acquire the tolerance against stress associated with absence of food of prime choice with better cocoon and shell association due to relative presence of certain free amino acids in the fourth and fifth instar larvae reared on interchange of food plants. Thus, L. parviflora can be utilized for tasar silkworm rearing in the fifth instar where the food of prime choice T. tomentosa is in scarce and L. parviflora is in abundance in the vicinity of farmer's hamlet.