A preliminary study on the pesticidal potencies of sweet orange (Citrus sinensis) peels on beans and maize weevils

Abstract

Insects act as both pests and vectors of disease-causing organisms to man and animals, thereby exposing them to secondary attacks. As grain pests, weevils cause harm, damage, destruction, reduction in grain quality and great economic loss. The use of synthetic insecticides have, over the years resulted in development of physiological resistance in the insects, environmental hazards as well as health problems to man and animals alike. The purpose of the study is to investigate ways of preserving food grains in a natural condition that could improve food security, maintain grain quality for a longer post-harvest period and provide alternative storage measure safer and less harmful to the environment, man and animals. This study assessed the pesticidal potencies of sweet orange (Citrus sinensis) peels on beans and maize weevils. The phytochemical screening of C. sinensis fruit peels revealed the presence of tannins, terpenes, anthraquinones, glycosides, resins, steroids and flavonoids. The beans and maize weevils upon treatment with varying concentrations of both the fresh and dried peels extracts (100mg/kg, 200mg/kg and 400mg/kg) showed a dose dependent significance (p<0.05) in the toxic activity on the weevils. The tannins and anthraquinones abundant in the fruit peel extracts of C. sinensis are known to exhibit acaricidal properties. The observed toxic effects could also be attributed to combined effects of various phytochemicals. These findings validate the traditional claims pertaining the use of orange peels in beans and maize preservations.