Biological studies on the Eri silkworm Attacus ricini Boisd. (Lepidoptera — Saturinidae)
1973
Gomaa, A. A.
An increase in temperature or relative humidity shortened the incubation period of eggs of Attacus ricini. At high temperature (30° C) and low humidity, (30%), all eggs failed to hatch. Data show an obvious increase in the percentage loss in weight of eggs with rise of temperature and decrease of humidity. The percentage of hatched eggs seems to be much affected by high temperature and low humidity. 25° C and 90% R.H. could be regarded as the optimum conditions for hatching. The larva passes through five instars, the first is the shortest, the last one being the longest. The prepupal stage occupies nearly the second half of the fifth larval instar. The duration of the larval stage is shortened by high temperatures. The pupal duration is much affected by temperature, but no apparent effect could be related to humidity or sex. Under conditions of low humidity and high temperature, pupae lose much weight. The moth longevity was increased by decreasing the tempereature, and female moths lived longer than males. The preoviposition, the oviposition and the postoviposition periods as well as the total number of eggs laid per female were increased by decreasing temperature.
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