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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 Mali. An oil‐based formulation of Metarhizium anisopliae (flavoviride) var. 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 fallows because they will die before reaching the farmers’ fields. However, if crops are infested by adults, the farmers can not wait for 6 to 10 days. An experiment was conducted in Mali using a mixture of a biopesticide and chemical pesticide. The mixture of lambda‐cyhalothrin (chemical insecticide) and Metarhizium anisopliae (flavoviride) var. acridum (biopesticide: oil‐based entomopathogenic fungus spore suspension) was applied to nymphs of Sahelian grasshoppers, using ultra low volume (ULV) sprayers. Both the mixture and lambda‐cyhalothrin alone gave quick mortality, with slightly higher mortality for the mixture. Mortality due to the Metarhizium treatments began 2 days after application and subsequently reached similar levels of mortality to the lambda‐cyhalothrin mixture treatments. The efficacy of the mixture was greater than Metarhizium alone. The efficacy of lambda‐cyhalothrin reached 80% on the day following application, but declined after 10 days, due probably to immigration of untreated grasshoppers.

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