The Potency of Three Botanical Powders in Preventing Cowpea Infestation by Weevil (Callosobruchus maculatus)
Callosobruchus maculatus is the main bruchid species attacking stored cowpea (Vigna unguiculata (L.) Walp) in West Africa causing high losses that leads to its subsidiary position in farming systems and the use of synthetic insecticides which are noxious to man and livestock and pollute the environment is presently being discouraged. Therefore, this research was mainly conducted to study the effectiveness of three indigenous medicinal plant powders viz., Bitter leaf (Vernonia amygdalina), Cashew (Anacardium occidentale) and Rose imperial (Cochlospermum tinctorium) as alternative at controlling the weevils. Twenty grame cowpea was treated with two different dosages i.e. 1g/20g and 4g/20g of different botanical powder and pirimiphose methyl (0.1 and 0.4g). Ten adult pairs (males and females) of C. maculatus were introduced in to each of the treatments and a control at 0, 5, 10, 15 and 20 weeks after treatments had been added. Three replication of each treatment were made and observations were recorded for 11 days. Data on the mortality, the number of eggs laid, daily adult emerged, developmental period and number of seeds damage were recorded. The results showed that the mean number of dead, number of eggs laid, adult C. maculatus emerged, developmental period and number of seeds damage were significantly (P<0.05) lower in all cowpea treated with botanical powder than untreated cowpea. Amongst the treated cowpea, mean values of the above four parameters assessed were all lower at higher dose (4g/20g). The results indicated that higher dosage of botanical powder were highly effective against C. maculatus infestation and damaged. Of all the botanical powder used, C. tinctorium give the highest check on the infestation while V. amygdalina was least effective. Since these botanicals are indigenous, readily available to small scale farmers, biodegradable and minimized environmental pollution, their use as insecticidal against C. maculatus should be encouraged.