NERVOUS AND HORMANAL FACTORS AFFECTING THE REPRODUCTIVE EFFICIENCY OF Spodoptera littoralis FEMALE MOTHS

Abstract

Mating process in Spodoptera littoralis female moths started 2 – 3 hrs after light off and the peak of mating was noticed 6.30 – 7.30 hrs after starting the scotophase period. Most of allatectomized females were observed to mate successfully with normal males. In virgin moths, 3 day old normal female laid an average of 371.84 eggs and found a mean of 11.76 eggs in its ovarioles, with a total number of 383.60 eggs/ female as fecundity. The relatively same numbers were found in case of sham operated females. . The reduction in total number of eggs in sham operated virgin females was only 3.97%. The opposite was, however, true in case of allatectomized females. Few number of eggs was produced by allatectomized females as compared with those of non-operated females. Mean of 12.26 eggs were laid and 15.56 eggs were found in the ovarioles with a total number of 27.82 eggs per allatectomized female, representing a reduction rate of 92.75% as compared with the fecundity of non-operated females. Transection of the ventral nerve cord (VNC) of females did not affect mating success. Transected VNC of females at emergence and mated 24 hrs later exhibited mating-induced stimulation of egg production. The mating signal, in this case, may not be transmitted through the VNC, but it may be due to the release of chemical factor into the haemolymph that activates the brain to release an allatotrophic hormone which affects corpora allata to secrete the juvenile hormone. Such hormone. Such hormone causes the physiological changes of mated females.