EFFECTIVENESS OF HIGH TEMPERATURES AGAINST CALLOSOBRUCHUS MACULATUS (Coleoptera: Bruchidae) ADULTS

Abstract

Pulse beetle, Callosobruchus maculatus is a worldwide severe pests of pulse grains in the storage conditions. Considering the negative consequences of synthetic chemicals used against C. maculatus, effectiveness of various high temperatures were evaluated against it under lab conditions. The Classic® 1080 series laboratory oven (HT Company (Ilford) Ltd. UK) was used to get the desired temperatures of 40, 45, 50, 55, and 60ºC. Five pairs of freshly emerged C. maculatus adults were placed with twenty cowpea seeds in a petri dish were used for each temperature regime for five exposure times i.e., 10, 20, 30, 40, and 50 minutes. Data on adult mortality was observed after 24-hours. Results confirmed the effective of high temperatures against adult C. maculatus as 100% mortality of the targeted adults was recorded within 10 minutes at 60°C, whereas it took 40- and 50-minutes to kill 100% of the adults at 55 and 50°C, respectively. The LT50 values of required temperature against C. maculatus at various exposure timings ranged between 43.544°C at 50 minutes exposure to 48.994°C at 10 minutes exposure, whereas overall minimum and maximum fiducial limits for LT50 temperatures were ranged between 42.845 to 49.655°C. No negative impact of high temperatures was also recorded on the germination percentage of cowpea seeds as germination success recorded at various high temperatures was not significantly different from the control cowpea seeds.