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Abstract
The objectives of this work were to evaluate toxicity of certain insecticides including the biocide Bioguard in
addition to some chinaberry Fruit extracts against the greater sugar cane borer,sesamia crelica.Changes in the
activity of acetylcholinestrase, phenoloxidase and total soluble protein as a result of insecticide treatment were
also investigated.The results showed that all tested insecticides resulted in Si~l:;t!~:::r;etductions of S.crelica
infestation in maize under open field condition. Such percent reduction was time-dependent for all treatments to
reach95% ,93%, 90.9% and 82% after 3 weeks for methoinyl, carbaryl, chlorpyrifos and Bioguard respectively.
-Based on LC50values for tested extracts and insecticides against the 3’d instar larvae after 3 days from
application of treated artificial diet, methanol extract showed. LC50 value of(6 rng/ L)and was the most effective
among tested substances follwed by acetone extract (7mg/ L) .chlorpyrifos (4ImgIL), carbaryl (86mgIL)
.rnethomyl (145mg IL ) ,Bioguard (298mg/L), and petrolurn ether extract ( 3349m!!fL ) .
-The resalts clearly showed that chloropyrrifos, carbaryl and rnethomyl ;1: LLL) revel caused inhibition of
acetylcholinesterase activity and such inhibitory power values were seeming equal and correlated to the toxic
effect of tested insecticides.
-The results also revealed that all treatments except Bioguard at LC25level caused decreases in protein
content.The highest reduction (95% ) of protein was found in methanonl extract - treated 3’d instar larvae.
However, Bioguard - treated larvae showed 95% increase in protein content. This may indicate that the mode
of action of such extracts are completely different from that of Bioguard . Moreovcr.chinaberry fruit extracts •
resulted in elevation of phenoloxidase activity. Methanol extract caused the highest increase (93.6%) in
phenoloxidase activity. However, Bioguard caused a great inhibition (72.3%) of the enzyme activity. Such
profound effects of these extracts and Bioguard offer an alternative safe substances that can be used through an
integrated pest management program for the control of corn borers such as S cretica.