<i>ANNONA</i> SPECIES AS INSECTICIDES

Abstract

By extraction and precipitation from several solvents the toxic principle present in Annona reticulata and A. squamosa seeds and roots has been concentrated up to one hundred‐fold. A preliminary chemical examination of this concentrate is described, leading to the conclusion that the toxicity is due to a glyceride or glycerides of a hydroxylated unsaturated acid or acids of high molecular weight. These extracts have been examined for contact and stomach poison and ovicidal properties in a variety of media. When used as a contact insecticide against Aphis fabae, Macrosiphoniella sanborni and Macronphum solanifolii , the concentrate exhibited a toxicity of the same order as that of rotenone, but against Oryzaephilus surinamensis the toxicity was considerably less. As a stomach poison the ether extract was both toxic and repellent to Plutella maculipennis larvae, but was neither toxic nor repellent to Diataraxia oleracea larvae. Ovicidal tests against the eggs of Plutella maculipennis and of Ephestia kühniella were inconclusive. The potency of this concentrate is therefore of a limited nature and although of roughly the same order as that of rotenone to certain aphides, it has neither the intensity of effect nor the range of insecticidal action of that compound.