Abstract
The effects of neemarin at 5, 10, 15 and 20 mg l super(-1) on the life table indices of Plutella xylostella (L.) were studied on cauliflower in the laboratory. Survivorship was increased with increasing concentrations. A total of 69% eggs hatched at 20 mg l super(-1) compared 85% in the control. Mortality (dx) of 1st instars was higher than the other instars in both exposed and unexposed individuals. Life expectancy (ex) was high in the untreated control and reduced at 20 mg l super(-1). Development times of immatures were prolonged to 32 days at 20 mg l super(-1) as compared to 18.6 days in the untreated control. Neemarin significantly reduced the emergence of adults. Potential fecundity (Pf) was 34 females/female/generation at 20 mg l super(-1) and 92 in the control. The net reproductive rate (R0) was significantly reduced with the increase in concentration. The intrinsic rate of increase (rm) and finite rate of increase ( lambda ) were significantly decreased at 20 mg l super(-1) as compared to other concentrations tested and in the control. Mean generation time (Tc) and corrected generation time (I) were prolonged at 20 mg l super(-1) and significantly differed to those of the untreated control. Doubling time (DT) was significantly extended to 28.4 days at 20 mg l super(-1) as compared to 6.1 days in the control.