Combined influence of gamma Radiation and low Temperatures on Reproduction of the cotton Leaf worm Adults, Spodoptera Littoralis (Boisd.)

The present study dealt with the effect of three low temperatures (4, 10, and 20 degree) and/or a sub sterilizing dose of gamma radiation 100 Gy on the adult cotton leaf worm, Spodoptera littoralis among P1 and F1 generations. Different biological aspects as mating ability, average number of spermatophores per mated female, percentage of mated female with sperm, average number of eggs and egg hatch were studied. Generally, low temperature did not affect either mating ability or average number of spermatophores. Also, the percentage of mated female with sperms was varied and did not follow a certain trend. The average number of eggs was significantly decreased by lowering the temperature used, while egg hatch percentage was significantly different from control and other temperatures tested especially at 4 degree. The same tread was observed among F1 generation except when TM crossed with TF where the percentage of mated female with sperms was clearly reduced than in the other treatments. In the combined treatment, the mating percentage was clearly reduced among P1 generation while it was slightly reduced in F1 treated female. The average number of spermatophores was around the control value at P1 and F1 generation, where mated female with sperm was sharply reduced. Average numbers of deposited eggs were not significantly different among treatments but it was only significantly different than in control through P1 and F1 generation except at P1 TM. Egg hatch percentage was significantly different in treatments compared with control. Generally, 4 degree was the most effective temperature