Assessment of the Larvicidal Potency of Bacillus thuringiensis Against the Moth of Spoladea recurvalis on Amaranths Plant

The control of Spoladeare curvalis, a major pest of amaranth plant, has been through the use of synthetic pesticides which have been reported to have detrimental effects. This study was aimed at assessing the larvicidal potency of B. thuringiensis against the larvae of Spoladea recurvalis on amaranth plant. The assessment of the larvicidal potency of B. thuringiensis isolates from cow range land and refuse dump sites in Zaria metropolis habouringCry1 gene (CR2, CR4, RD1) was carried out by spraying spore crystal mixture of B. thuringiensis isolates on amaranth plants infested with Spoladea recurvalis larvae. The mortality of S. recurvalis larvae, under a screen house were assessed after 24, 48 and 72hours of exposure to the spore crystal mixture of B. thuringiensis isolates. Spore crystal mixtures of B. thuringiensis isolates were effective in causing larvae mortality with more than 60% mean mortality rate of S. recurvalis larvae after 72hours of exposure. The mortality rate of Spoladea rescurvalis increased with increase in exposure period. Spore crystal mixture of Bacillus thuringiensis isolates should be considered as an alternative to synthetic pesticides for the control of Spoladea recurvalis larvae on amaranth plant. Keywords: Bacillus thuringiensis; spore; larvae; amaranth; larvicidal.