Effects of Garlic Oils on the Fecundity and Hatchability of Callosobruchus maculatus L. (Coleoptera: Bruchidae)

Abstract

Laboratory experiments were conducted to evaluate the efficacy of the three types of garlic oils; Sudanese, Chinese and Egyptian on the eggs of cowpea beetle Callosobruchus maculatus. Volatile oils from Sudanese and Chinese garlic were obtained by steam distillation and Soxhlet extraction using ethanol correspondingly, whereas Egyptian garlic oil was bought as a ready-made product. The oils were tested at concentrations of 0.01%, 0.1%, 1%, 5% and 10%, at exposure periods ranging from 24-72 hrs. Respective average number of eggs laid after exposure to the lowest concentration of Sudanese, Chinese and Egyptian oils were; 5.4, 4.0, 4.1 after 24 hrs; 0.7, 0.1, 0.1 after 48 hrs 0.2, 0.5, 0.5 after 72 hrs. The oils from the three garlic cultivars significantly reduced number of eggs laid with the highest dose (10%) caused complete inhibition of egg laying. Average number of eggs hatched when exposed to the lowest concentration (0.01%) were; 0.25 after one day and 1.00 after 7 days of exposure to Sudanese oil vapours, 0.00 after one day and 0.75 after 7 days of exposure to Chinese oil vapour and 0.00 after one day and 0.75 after 7 days of exposure to Egyptian oil vapour.