Laboratory studies on the effects of triphenyltin acetate and triphenyltin hydroxide on the stages in the life-cycle of Spodoptera littoralis (Bois.).

Spodoptera littoralis (Bois). were reared in the laboratory and the effects of triphenyltin acetate (TPTA) and triphenyltin hydroxide (TPTH) were studied on the various stages o f the life-cycle. First, second and third instar larvae were very susceptible to TPTA and TPTH at the dosage rates tested when applied as a cover spray to maize leaf sections, which were used as food for the larvae. Fourth instar larvae showed a certain amount of tolerance to these compounds but were also very susceptible. Fifth and sixth instar larvae were more tolerant although a high percentage did succumb due to the antifeedant effect of these compounds. Treated pupae showed a marked sensitivity to the higher concentrations of these compounds tested and the reproductive potential of the adults developing from treated pupae showed a marked decrease in respect of both production and hatching ability of the eggs. The same tendencies were followed by adults receiving an oral dose of the compounds. Eggs of S. littoralis were inclined to be sensitive to treatments by these compounds but only at high dosages. Throughout, TPTA and TPTH exhibited a toxic effect on the individuals, as well as an antifeeding effect on the larvae and a reproduction inhibition effect on adults