Effects of sublethal dose of Bacillus thuringiensis H-14 exposure on Aedes albopictus (Diptera: Culicidae)

Abstract:
Sublethal effects were studied at the parental and offspring stages which has been exposed to Bti at the larval stage (parental) in comparison to the control untreated group. Biological aspects inclusive of blood-engorgement rate and fecundity (number of eggs produced) of the parental stage were studied. For the offsprings, study variables include offspring survival rate and developmental period (number of days required at every life stage). Late third/early fourth instar larvae (parental) were exposed to Bti at LC50 (16.75 ITU/L). Larvae that survived from treatment were further cultured to study the sublethal effects of Bti compared to the control untreated group. Aedes albopictus larva, pupa and adult survival rate was significantly reduced (p=0.05) either at the parental stage or at the offspring stage after treatment with Bti at a dosage of LC50 compared to control. Lower blood-engorgement rate was recorded by the treated group compared to control. Aedes albopictus treated with Bti at the sublethal dose (LC50) in this study demonstrated lesser egg production compared to the control group. The offsprings took a longer time to develop from egg to adult. Reduction in the number of eggs produced and increased immature developmental period, are added advantages that makes Bti suitable for the control of mosquitoes.