Biological effect of methanol extracts of Candlewood <i>Zanthoxylum xanthoxyloides</i> (Lam.) against infestation of stored maize and cowpea by three stored product beetles

Abstract

Methanol extract of dried leaf (DLE), dried bark (DBE), dried root (DRE), fresh bark (FBE) and fresh root (FRE) of Zanthoxylum xanthoxyloides (Lam.) was assessed in the laboratory against infestation of Sitophilus zeamais, Callosobruchus maculatus and Tribolium castaneum in stored maize and cowpea. One hundred grams each of maize and cowpea were treated with 2 ml of each extract to test for contact toxicity, damage assessment, progeny production, effect on immature and developmental stages of S. zeamais and C. maculatus. Furthermore, contact toxicity by topical application and repellency test using a choice bioassay method were carried out on the three insect species. Results obtained showed that FBE and DBE applied topically caused significant (P<0.001) mortality of the three insects. Fresh bark extract also significantly (P<0.001) reduced grain damage and completely inhibited progeny production and development of eggs within grain kernels. All the extracts evoked a strong repellent action against T. castaneum but were moderately repellent to S. zeamais and C. maculatus. The potentials of using extracts of Z. xanthoxyloides as grain protectant against infestation by storage pests is being discussed.


KEY WORDS: Zanthoxylum, Extract, Stored product, Beetles, infestation.


Global Jnl Pure & Applied Sciences Vol.10(2) 2004: 227-234