Physiological changes in reproduction of Spodoptera litura (fabricius) on exposure to pyriproxyfen

Effects of sub-lethal dose of pyriproxyfen on the reproduction of second instar Spodoptera litura larvae as reported. At LC30 and LC50 concentrations, pyriproxyfen influenced the pre-oviposition period (4.7 d as compared to 1.4 d in control), oviposition period (2.2 d as compared to 5.2 d in control), post-oviposition period (2.1 d as compared to 1.0 d in control), fecundity (144.9 eggs as compared to 805.8 in control), egg size (0.012 mm3 as compared to 0.027 mm3 in control), reproductive effort (1.76 as compared to 21.76 in control), egg hatchability (76% as compared to 92% in control) and survival of newly emerged larvae (66% as compared to 92% in control). Ultrastructural studies revealed reduced dimensions (0.0004 ± 0.0002 mm3) of the ovarioles in the treated females. The observed effects of pyriproxyfen on the reproductive physiology of the insect suggest that it can be used as a control tool for the management of S. litura populations.