Temperature impacts on the eggplant shoot and fruit borer Leucinodes orbonalis: a life table approach

Abstract

The eggplant shoot and fruit borer (ESFB), Leucinodes orbonalis Guenee (Lepidoptera: Pyralidae) is a notorious insect pest that causes havoc across all eggplant cultivation areas in Bangladesh. Remarkably, its relationship with environmental factors such as temperature is not clearly defined. We measured the effects of a range of temperatures (22, 24, 26, 28, and 30 °C) on the population growth parameters of ESFB under laboratory conditions (60 ± 5% relative humidity and 16 L:8 D photoperiod), developing an age-stage, two-sex life table. Results indicate that temperature significantly reduced development times and adult total lifespan and affected ESFB life table parameters (P < 0.05). Specifically, the egg hatching time reduced from 5 days at 22 °C to 3 days at 30 °C, while larval and pupal duration reduced from 12 to 8 days and 10 to 7 days respectively. Thus, the generation time (T) was longer (29 days) at 22 °C and shorter (22 days) at 30 °C; meanwhile, the highest fecundity (61 eggs per female) was recorded at 28 °C and the net reproduction rate (Ro) was higher at 24–30 °C, being (18–24) offspring/individual. Consequently, the ESFB population reared at 28 °C and 30 °C had higher finite rates (λ = 1.15 and 1.14 respectively) and intrinsic rates of natural increase (r = 0.14 and 0.13 respectively), testifying the most suitable temperatures for their growth and reproduction. Our findings contribute to understanding ESFB bionomics and occurrences, and thus, might enhance implemented management strategies, particularly in developing pesticide application schedules.