The diamondback moth, Plutella xylostella (L.), is an important international pest of cruciferous vegetables. The effects of the new diamide insecticide chlorantraniliprole, at a lethal concentration inducing only 25% mortality (LC25), were assessed on the development and reproductive parameters of P. xylostella under laboratory conditions. In addition, effects on development time, pupation rate, larval and pupae weight, fertility, and survival in the parent and F1 generations were assessed. When 4th instar P. xylostella larvae were exposed to LC25 of chlorantraniliprole on a cabbage (Brassica oleracea var. capitata L.) leaf for 96 h, we observed increased developmental time for 4th instar larval to pupa period (4.27 days vs. 3.34 days in the control), lower pupal weight (3.58 mg vs. 4.17 mg in the control) and decreased adult fecundity (by 42%). F1 generation underwent transgenerational effects, i.e. higher developmental time from egg to pre-pupae and lower egg hatching rate occurred. Demographic growth parameters, such as the net reproductive rate (R-0), the intrinsic rate of increase (r(m)), and finite rate of increase (lambda) were significantly lower for the LC25 chlorantraniliprole treated group than for the untreated control. Our results suggest that exposure to LC25 of chlorantraniliprole may have negative effects both on exposed individuals and on subsequent generations in P. xylostella.