THE SYSTEMIC INSECTICIDAL ACTION OF SODIUM FLUOROACETATE AND OF THREE PHOSPHORUS COMPOUNDS ON THE EGGS AND LARVAE OF PIERIS BRASSICAE L.

Abstract

Four compounds, bisdimethylaminophosphonous anhydride (anhydride), bis(dimethylamino)fluorophosphine oxide (oxide), diethyl paranitrophenyl phosphate (E600) and sodium fluoroacetate (acetate), previously shown to have systemic insecticidal activity against aphids, have now been tested against the eggs and larvae of Pieris brassicae L.The anhydride proved to have very little toxic action on Pieris, but the other three compounds showed both contact toxicity and systemic insecticidal action when taken up by the roots of cabbage plants from solution and from soil. The acetate, but more especially the E600, also showed systemic action following application to the leaves.In all cases the order of decreasing toxicity was E600 > acetate > oxide > anhydride. E600 is the only compound which is outstandingly toxic to Pieris eggs and larvae. It has the added interest that when watered on to the roots of cabbage plants it kills larvae in egg batches on the leaves. Death takes place at the stage when the larvae are biting through the shells. The oxide and acetate proved to be surprisingly innocuous.Unless it is felt to be too poisonous E600 is worthy of consideration as an insecticide against Pieris eggs and larvae, since it is highly effective as a contact insecticide and also has some systemic action.