Effect of a mixture of lambda-cyhalothrin and spores of Metarhizium anisopliae (flavoviride) var. acridum Driver and Milner (biopesticide) applied tograsshopper larvae in Mali

A mixture of lambda-cyhalothrin (lambda-cyhalothrin: chemical insecticide) and Metarhizium anisopliae (flavoviride) var. acridum Driver and Milner. an entomopathogenic fungus (bioinsecticide) was used for grasshopper control in Mall. An oil-based formulation of Metarhizium anisoliae (flavoviride) va r. acridum Driver and Milner has been developed by LUBILOSA a collaborative project for locust and grasshoppers control. It takes 6 to 10 days for the biopesticide to kill the hosts, which is not a problem for larvae in fallo ws because they will die before reaching the farmers' fields. However, if c rops are infested by adults, the farmers can not wait for 6 to 10 days. An experiment was conducted in Mall using a mixture of a biopesticide and chem ical pesticide. The mixture of lambda-cyhalothrin (chemical insecticide) an d Metarhizium anisopliae (flavoviride) var. acridum (biopesticide: oil-base d entomopathogenic fungus spore suspension) was applied to nymphs of Saheli an grasshoppers, using ultra low volume (ULV) sprayers. Both the mixture an d lambda-cyhalothrin alone gave quick mortality, with slightly higher morta lity for the mixture. Mortality due to the Metarhizium treatments began 2 d ays after application and subsequently reached similar levels of mortality to the lambda-cyhalothrin mixture treatments. The efficacy of the mixture w as greater than Metarhizium alone. The efficacy of lambda-cyhalothrin reach ed 80% on the day following application, but declined after 10 days, due pr obably to immigration of untreated grasshoppers.