Laboratory Evaluation of Insecticidal Activities of Some Botanicals against Four Insect Pests of Honey Bees (Apis mellifera L.)

Abstract

The study evaluated the effectiveness of methanol, n-hexane and aqueous leaf extracts of Ocimum gratissimum, Carica papaya, Tithonia diversifolia, Ageratum conyzoides and Azadirachta indica in the management of four insect pests of honeybees namely; acrobat ant (Crematogaster lineolata), small hive beetle (Aethina tumida), lesser wax moth (Achroia grisella) and greater wax moth (Galleria mellonella) in the laboratory. Test of contact toxicity of the extracts was conducted by topical application of 2 ml of treatments at 10% w/v on five insects using standard method. Repellency study of the extracts was conducted using an area of preference test. N-hexane extracts of all the plants caused 100% mortality of all the insects within 6 hour. Methanol extract caused between 90% and 100% mortality of all the insects except A. tumida. Aqueous extract of all the plants cause 100% mortality of C. lineolata, but induce no mortality of A. tumida. Mortality of other insects treated with aqueous extracts of the plants varied between 15% and 100%. The % repellence of A. grisella by plant extracts and cypermethrin varied between 45% and 90% and were not significantly (p>0.05) different from each other, while that of A. tumida varied between 35% and 78%. The n-hexane and methanol extracts of the five plants had repellence and insecticidal effects on the four insect pests of bees and could be considered as bioactive candidate for management of the insects.