INSECTICIDAL AND TOXICOLOGICAL STUDY OF Dennettia tripetala (G. Baker) FRUIT OIL EXTRACT USED AS COWPEA GRAINS PROTECTANT AGAINST Callosobruchus maculatus (Fab) (COLEOPTERA: CHRYSOMELIDAE) INFESTATION

Abstract

Dennettia tripetala fruit ethanolic oil extract was investigated for its insecticidal property. Bioassay was conducted at 0.2, 0.4, 0.6, 0.8 and 1.0ml/20 g of susceptible cowpea. Results indicated that 1.0 ml dosage was the most effective as it evoked 100% beetle mortality within 24 h of application and its effect was significantly (p<0.05) different from other treatments except the positive control that recorded up to 94% mortality of the beetles. All dosages displayed significant lethal effects on the insect as compared with the untreated check. Insect mortality was dosage dependent. Probit analysis showed that, fruit oil extract required 2.46 and 6.66ul to achieve 50 and 95% highest insect mortality within 24 hours. Treated seeds with highest dose of 1.0 ml D. tripetala extract prevented oviposition, adult emergence as well as ability of the insect to cause damage and weight loss, hence reduced infestation and subsequent damage of treated cowpea seeds. Thus, Dennettia tripetala extract could be a potential toxicant and of great importance in storage protection of stored cowpea against the bruchids. The bilirubin, GGT and Uric acid were high as the dosages increased. Positive control showed significantly higher concentration of Bilirubin - 69.11g/dl, GGT - 38.02g/dl Uric acid - 50.25g/dl while Total protein was at its least (0.06g/dl) when compared to other groups. The low values of AST (Aspartate Aminotransferase), ALP (Alkaline Phosphate), ALT (Alanine Aminotransferase) and Creatine concentrations recorded at 1.0ml of 2% concentration of D. tripetala oil extract has no hepatotoxic effect on animals.