Abstract
Two synthetic pyrethroids, viz., cypermethrin (cymbush 25 EC) and fenvalerate (simicidin 20 EC); three organophosphate, viz., malathion (malathion 50 EC), acephate (starthene 75 SP) and monocrotophos (crotocal 36 EC); and one extract of neeem (ashirwaad) were evaluated for relative toxicity against the last instar larvae of Atteva fabriciella Swed., a defoliator of Ailanthus excels Roxb. of the six insecticides tested, the order of toxicity was cypermethrin > monocrotophos > acaaephate > malathion > neem extract. Cypermethrin was found to be the most effective and 17.965 times more toxic han malathion.
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