Biotechnologie, Agronomie, Société et Environnement (Jan 2013)
Réduction des doses efficaces d'insecticides contre les larves de criquet pèlerin (Schistocerca gregaria Forskål, 1775 : Orthoptera, Acrididae) par utilisation de quantités réduites de phénylacétonitrile
Abstract
Reduction of effective doses of insecticide against desert locust (Schistocerca gregaria Forskål, 1775: Orthoptera, Acrididae) nymphs using phenylacetonitrile. In order to reduce the amount of insecticides used during a locust upsurge, phenylacetonitrile (PAN) was tested in 2007 and 2008, in the Niamey area (Niger). PAN was used, on the one hand, in topical applications on third stage nymphs (L3) of the desert locust, alone or in combination with reduced amounts of various insecticides (lambda-cyhalothrin, malathion, chlorpyrifos-ethyl). In addition, experiments were carried out in semi-natural conditions, in field enclosures, and also on third stage nymphs of the desert locust. Insecticides were each applied at the recommended dose and at half of that dose with the addition or not of phenylacetonitrile. All topical applications of insecticides led to the total mortality of the nymphs within 1 to 24 h; the use of PAN alone caused a mortality rate of no higher than 18% within 120 h. In the field enclosures, mortality rates for the desert locust nymphs were the same both with the recommended doses and with half of the dose with the addition of 10 ml of PAN·ha-1. Results indicate that the addition of small quantities of phenylacetonitrile could make it possible to decrease by half the quantities of insecticides used in the control of desert locust nymphs, while preserving the same effectiveness.
