Impact of temperature on some biological traits of Habrobracon hebetor (Hymenoptera: Braconidae)

Life history attributes of Habrobracon hebetor Say were investigated at six thermal regimes (20, 22.5, 25, 27.5, 30 and 32.5 ºC, 65±5 % RH and a photoperiod of 16:8 h L:D) using Galleria mellonella L. larvae as lab host. About 80-250 fresh eggs of the parasitoid (Cohort) were reared under different thermal treatments. Incubation period of male and female eggs reduced significantly from 4.12 and 3.45 days at 20 ºC to 1.25 and 1.06 days at 27.5 ºC, respectively. Larval development was 7.00 and 6.81days for male and female larvae at 20 ºC and decremented to 2.43 and 2.47 days at 32.5 ºC, respectively. Similarly, the longest and the shortest male and female pupal duration was observed at 20 ºC (16.12 and 18.27 days) and 32.5 ºC (5.05 and 5.02 days), respectively. Adult male and female longevity was longest (42.83 and 58.44 days) at 20 ºC and shortest (16.05 and 14.02 days) at 32.5 ºC, respectively. Population parameters including R0, r, and λ ranged between 4.98-28.81 offspring, 0.0378-0.2001 d-1 and 1.0351-1.2065 d-1, respectively, when temperature increased from 20 to 27.5 ºC, proving about 5 folds enhancement in r. Generation time was 42.50 days at 20 ºC and decreased to 15.16 days at 32.5 ºC, respectively. Female wasp required at least 2.62 days at 27.5 ºC and maximum 8.18 days at 20 ºC to start oviposition. It is concluded that the population characteristics of H. hebetor were statistically superior at 27.5 ºC compared with those in other treatments and considering economy of rearing, 27.5 ºC along with 65±5 and 16:8 L:D h would be the optimum conditions for its propagation on G. mellonella larvae.