Low and high temperatures for the control of cowpea beetle, callosobruchus maculatus (F.) (coleoptera: Bruchidae) in chickpeas

Chickpea (Cicer arietinum L.; Leguminasae) is an important pulse crop grown, around the world. The whole grain of chickpea is damaged by the cowpea seed beetle, Callosobruchus maculatus (Coleoptera: Bruchidae), which is the most important field-carry-over storage pest of pulses. The management of this insect in storage using chemicals leads to insecticide residues in grains and insecticide resistance development in insects. Thermal disinfestation is one of the means of physical insect control. Eggs, larvae, pupae and adults were held at 42 or 0 °C for varying durations. Pupae and adults were equally heat tolerant. The lethal time to reduce survival by 50% (LT50) at 42 °C for eggs, larvae, pupae and adults were 18, 57, 78 and 71 h, respectively. Pupa was the most cold-tolerant stage. The LT50 at 0 °C for eggs, larvae, pupae and adults were 3, 8, 10 and 4 d, respectively. The LT50 for pupae were 4907, 4262, 336, 36 and 13 min at the grain temperature of 42, 45, 50, 55 and 60 °C, respectively. The LT50 of pupae at 0,−5,−10 and −15 °C were 274, 122, 7 and 2 h, respectively.