INSECTICIDAL EFFECTS OF THE ETHANOLIC EXTRACT OF PSEUDOCEDRELA KOTSCHYI AGAINST DERMESTES MACULATUS (COLEOPTERA: DERMESTIDAE) ON TREATED DRIED CATFISH (CLARIAS GARIEPINUS)

Résumé

This research work was carried out to assess the insecticidal properties of the ethanol extract of Pseudocedrela kotschyi in the control of Dermestes maculatus infesting dried fish (Clarias gariepinus) in storage. Ethanol extract of P.kotschyi was administered in different concentrations to dried fish infested with larvae and adult stages of D.maculatus. 96 gram of dried fish sample was divided into 12 groups of 8 g each and each group was subdivided into three (3) replicates of 2.7g of dried fish in each treatment. For the bioassay test, groups 1-6 were infested with 10 larvae of D. maculatus each and treated with 0.1, 0.5, 1.5, 3.0, 6.0, and 9.0g of plant extract respectively. Groups 7 and 8 were infested with 10 adult D.maculatus and treated with 3.0 and 9.0g of plant extract respectively. Groups 9 and 10 were infested with 10 larvae and adult D.maculatus respectively and treated with 9.0g of standard insecticide each. Groups 11 and 12 were infested with 10 larvae and adult D. maculatus respectively but not treated with either the plant extract or pestox (standard insecticide) but as controls. The set-up was monitored daily for seven days. In the groups treated with the plant extract, the highest mortality rate was observed in smoked fish treated with 0.1g (2.23%) plant extract while the mortality rate of 1.1 % each was recorded in smoked fish treated with 1.5g and 9.0g plant extracts, compared 4.44 % recorded in the untreated (control). The extract had no significant (P>0.05) effect on the mortality of the insects. The groups treated with 9 g pestox (standard insecticide)recorded the highest mortality 25 (27. 78 %) compared to the groups treated with the plant extract. The ethanol stem bark extract of P.kotschyi reduced the activities of D.maculatus larvae and adults.