Effect of crude phenolic extracts of Nerium oleander L. leaveson the biological performance of Bemisia tabaci(Genn.)(Homoptera: Aleyrodida)
Abstract
Laboratory bioassays were done to determine the toxicity of crude phenolic extracts of
Nerium oleander leaves to whitefly Bemisia tabaci . Crude phenolics applied at
concentrations of 0.1 , 0. 2 , 0.5 , 1 , 2 % . The egg was generally the least susceptible
stage to all test treatments .The results indicated that the concentration of 2 % was the
most effective . At this concentration eggs mortality reached 45.02%, in crude phenolic
differences in nymphal mortality according to age was observed at all concentrations of
phenolic extract , both first and third nymphal instars had higher mortality with phenolic
extract at concentrations of 1% and 2% than second nymphal instar . Pupal and adults
mortality reached 82.63% and 60.45% when treated with crude phenolics at concentration
of 2% respectively . Cumulative mortality reached 100 % at concentration of 1% and 2 %
in second nymphal instar and adults respectively when treated with crude
phenolic.Development time of immature stages of B.tabaci also , affected by the
application of crude phenolic extracts of N. oleander leaves , generally development
period prolonged in all treatments of phenolics as compared with control treatment
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