Effects of low temperatures on adult survival and reproduction of Rhyzopertha dominica

Laboratory trials were carried out on the influence of low temperatures on adult survival, reproduction and egg hatch of the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera Bostrichidae). Temperatures of 3, 7, 12, 17 and 27 °C were studied. Results show the lethal time (LT) required for killing 5%, 50% and 95% of the tested insects was significantly affected by temperature but not adult age. Beetles died sooner at 27 °C than at the lower temperatures. In fact the LT5 at 27 and 3 °C was 1.12 days and 2.27 respectively. On the contrary, the mortality rate of 95% was reached most quickly at 3 °C (12.57 days) and the time increased as temperature went up. The females of the lesser grain borer were able to oviposit at temperatures between 27 and 7 °C; but after 50 days of incubation at 27 °C only the eggs laid at 27 °C were able to hatch.