INSECTICIDAL ACTIVITY OF GARLIC (Alium sativum (L.)) OIL ON Callosobruchus maculatus (F.) IN POST-HARVEST COWPEA (Vigna unguiculata (L.) WALP.)

Abstract

Studies were conducted to determine the effect of garlic oil on Callosobruchus maculatus (F.) in three cowpea varieties (Borno brown, Mubi white and Iron beans).  Ten grams in 3 replicates for untreated (check) and 4 levels of garlic Alium sativum (L.) seed oil treatments (0.1, 0.2,0.4 and 0.6 ml) were infested with 3 pairs of 0 - 3 days old C. maculatus for pre and post oviposition.  Experiments were conducted under ambient conditions of 25- 30oC and 27 - 56% relative humidity.  Data on number of eggs laid and progeny emergence were subjected to analysis of variance (ANOVA).  Significantly different means were separated using the Least Significant difference at 5% level of probability.  Result showed that the number of eggs laid and adults that emerged from untreated grains of the varieties were each significantly  (p<0.05) different from the number of eggs that were laid and adults that emerged from all treated grain of the varieties.  The study also showed that cowpea grains infested with 1 - 5 day old eggs of C. maculatus can be prevented from damage by the bruchid.  Grain treatment with garlic oil before oviposition drastically suppressed oviposition, egg-hatch and development by the cowpea bruchid consequently the emergence of few to zero adults.  Both pre and post oviposition grain treatments were effective in the management of the beetle. However, treatment before oviposition appeared to be more effective in protecting cowpea grains against infestation and damage.

 

Key words: Damage, C. maculatus, garlic oil, varieties, pre-oviposition, post-ovipotion