Effect of neemarin on life table indices of Plutella xylostella (L.)

The effects of neemarin at 5, 10, 15 and 20 mg l⁻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⁻¹ compared 85% in the control. Mortality (d_x) of 1st instars was higher than the other instars in both exposed and unexposed individuals. Life expectancy (e_x) was high in the untreated control and reduced at 20 mg l⁻¹. Development times of immatures were prolonged to 32 days at 20 mg l⁻¹ as compared to 18.6 days in the untreated control. Neemarin significantly reduced the emergence of adults. Potential fecundity (P_f) was 34 females/female/generation at 20 mg l⁻¹ and 92 in the control. The net reproductive rate (R₀) was significantly reduced with the increase in concentration. The intrinsic rate of increase (r_m) and finite rate of increase (λ) were significantly decreased at 20 mg l⁻¹ as compared to other concentrations tested and in the control. Mean generation time (T_c) and corrected generation time (τ) were prolonged at 20 mg l⁻¹ and significantly differed to those of the untreated control. Doubling time (DT) was significantly extended to 28.4 days at 20 mg l⁻¹ as compared to 6.1 days in the control.