Bio-insecticidal potency of five plant extracts against Cowpea Weevil,Callosobruchus maculatus (F.),on Stored Cowpea,Vigna unguiculata (L)

It is estimated that the global post-harvest grain losses caused by insect damage and other bio-agents ranged between 10 to 40%. small-scale farmers may lose up to 80% of their stock due to insect pest infestation after several months of storage. control measures are necessary; they are proactive,cost effective and safe. the present study was conducted to evaluate the insecticidal effect of ethanol extracts from five locally available aromatic plants,namely allium sativum l. (garlic),cordia millenii baker (manjack),monodora myristica (gaertn.) (nutmeg),xylopia aethiopica (dunal) (negropepper) and zingiber officinale roscoe (ginger) against callosobruchus maculatus (cowpea weevil) infesting cowpea seeds (vigna unguiculata l.). bioassay was done by a direct contact application of the extracts using three concentrations (50,75 and 100mg/ml) of each extract in 10g of previously disinfested cowpea seeds containing 10 adults of c. maculatus of 1-2 days old. the results revealed that all the plant species had lethal effects against the insect as compared with the untreated check. considering the lc50 of the extracts 96 hours post-treatment as a main index c. millenii appeared superior (lc50 = 36.3mg),followed by z. officinale (lc50 = 37.5mg),x. aethiopica (lc50 = 43.8mg),m. myristica (lc50 = 47.5mg) and a. sativum (lc50 = 55.0mg). all the tested plant species exhibited a toxic action against the cowpea weevils. these results have implications for cost effectiveness and safety that even the local farmers can use to protect stored cowpea seeds against the weevil. © 2017 jordan journal of biological sciences.