International Journal of Agricultural Science Research Vol. 4(1), pp. 013-020, January 2015 ISSN 2327-3321 ©2015 Academe Research Journals

Full Length Research Paper

Insecticidal activity of botanical pesticides on Callosobrunchus chinensis (L.) (Coleoptera: Bruchidae) in stored green gram, Vigna radiata (L)

Costancia Peter Rugumamu

Department of Zoology and Wildlife Conservation, University of Dar es Salaam, P.O. Box 35064 Dar es Salaam, Tanzania. E-mail: wrugu@udsm.ac.tz. Tel: +255 784 324382/ +255 754 610242.

Accepted 19 December, 2014

Abstract

Callosobrunchus chinensis is a pest of pulses including green gram, Vigna radiata, which is a good source of plant protein. Farmers in rural Tanzania apply botanical pesticides to protect green gram from insect pests. The botanicals used in Bubinza and Ngh’anya villages in Magu District were Azadirachta indica, Agave sisalana ash, Eucalyptus camaldulensis, Cymbopogon citratus and Tegetes minuta. Laboratory experiments investigated insecticidal activity of the botanicals against C. chinensis at different doses of 2.5%wxw; 5.0%wxw and 7.5%wxw during varying experimental periods. The findings revealed varying percentage mortality of C. chinensis as follows: Azadirachta indica > Agave sisalana ash > Eucalyptus camaldulais > Cymbopogon citratus >Tagetes minuta and the efficiency of the botanicals was reflected by the mortality of the insects that reached up to 100% in various doses while the LC₅₀ (C. chinensis) occurred at or below 2.5% during 1 – 7 days period. ANOVA showed significant differences, P < 0.0001 in the percentage mortality of C. chinensis among the botanicals at each dose. It was concluded that the botanicals possess high insecticidal activity against C. chinensis and hence could be employed in the management of C. chinensis infesting green gram.

Key words: Botanical pesticides, Callosobruchus chinensis, Bruchidae, green gram, insecticidal activity, mortality.