Full Length Research Paper

Biological effect of ethanolic extract fractions of Ricinodendron heudelotii (Baill) Pierre ex Pax against Sitophilus zeamais Motschulsky and Callosobruchus maculatus Fabricius on stored grains

I. O. Udo¹ and T. T. Epidi²*

¹Department of Crop Science, University of Uyo, P.M.B.1017, Uyo, Nigeria.

²Department of Crop Production Technology, Niger Delta University, Wilberforce Island, P.M.B. 071, Yenagoa, Bayelsa State, Nigeria.

*Corresponding author. E-mail: tepidi@yahoo.com.  Tel.: +2347031013839.

Accepted 3 August, 2009

   Abstract

Ethanolic extract of dried leaves of Ricinodendron heudelotii was partitioned between equal volumes of hexane, ethylacetate, chloroform, butanol and water to obtain the various fractions. These fractions were assessed in the laboratory against Sitophilus zeamais and Callosobruchus maculatus on stored maize and cowpea, respectively. 100 g each of maize and cowpea grains were treated with the extract fractions to test for contact toxicity, damage assessment and progeny production. Furthermore, contact toxicity on filter paper and toxicity by topical application as well as repellency test were also carried out. Results obtained showed a significant (P < 0.05) insect mortality when the fractions were applied topically and by grain treatment. There was also a significant reduction in damage caused while progeny development was very low. The extract fractions significantly repelled the 2 insect species with an overall repellency of 48%. This work recommends the incorporation of R. heudeotii into storage pest management systems.

Key words: Ricinodendron heudelotii, toxicity, repellency, stored grains, Callosobruchus maculatus, Sitophillus zeamais.