Entomotoxic efficacy of cayenne pepper, sweet pepper and long cayenne pepper oil extracts against Sitophilus zeamais infesting maize grain

Abstract

The study was conducted to evaluate the efficacy of cayenne pepper, long cayenne pepper and sweet pepper as protectant of maize grain against Sitophilus zeamais . The oils were extracted with n-hexane and used for the treatment of maize grains at dosage of 0.5, 1.0, 2.0, 5.0 and 10.0ml. The experiment was divided into three parts, those that were infested immediately after treatment (initial), and those that were stored for three and six months before been infested with S. zeamais. At the initial storage, oil of cayenne and long-cayenne pepper achieved 100% insect mortality within 96h and also prevented the damage and weight loss of the treated grains at all dosages. The effect of these oils were significantly (p<0.05) different from sweet pepper which only achieved 60% insect mortality after 110h at 10.0ml dosage. The efficacy of the oil extracts of these peppers was greatly reduced as the period of storage of treated grains was increasing. The extract of sweet pepper was unable to achieve complete mortality of S. zeamais after 110h of exposure, yielding less than 60% mortality. After six months of storage, only the extract of cayenne pepper was able to achieve above 50% mortality at 10ml dosage. However, at all dosages, the oils did not affect the viability of the treated grains. These oils could be integrated into pest management strategy as they may increase the marketability of botanical base insecticides. Moreso, they are been eaten by consumers on daily basis.