Criblage de pesticides homologués contre Tuta absoluta au Burkina Faso

The South American tomato pinworm, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is a leafminer species currently considered as one of the major pests of fresh tomatoes around the world. The species settled in north Africa in 2007, before being observed in the entire continent. Widespread insecticide use has led to the emergence of resistant populations in South America and Europe, but no large-scale insecticide resistance assessment has been performed in Sub-Saharan Africa so far. In this study, we collected T. absoluta larvae (extraction of larvae from infested tomato leaves followed by their deposition on leaves of live tomato plants placed in a cage) in vegetable growing sites of Burkina Faso where the pest was first detected in 2016. These sites are Ouahigouya (northern region), Goué and Loumbila (central plateau) and Pindga (central-southern region). Acute toxicity of the all-available molecules in Burkina Faso was evaluated in the laboratory on F1 individuals, including acetamiprid, abamectin, spinosad, cypermethrin, chlorpyrifos, λ-cyhalothrin, deltamethrin, and Bacillus thuringiensis. No LC50 differences among T. absoluta populations were highlighted, except for Bacillus thuringiensis. Insects were still highly susceptible to abamectin [LC50 < 0.4 mg/L; Control failure likelihood (CFL) =−25%], spinosad (LC50 < 0.6 mg/L; CFL = -25%) and chlorpyrifos-ethyl (LC50 between 254 and 458 mg/L; CFL =−15%), but were less susceptible to acetamiprid (CFL ranging from 72% to 91%), cypermethrin (CFL = 80%), λ-cyhalothrin (CFL =79%), and deltamethrin (CFL ranging from 51% to 66%), with LC50 values for these insecticides ranging between 100 and 525 mg/L. Pending a proper communication strategy, we hope this work could help producers avoiding the most inefficient active substances.