Niveau de sensibilité de la mineuse de la tomate (Tuta absoluta) à divers biopesticides

The tomato leafminer Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is a worldwide invasive pest of tomatoes that reached West Africa in 2010. Synthetic insecticides remain the most widely used method of control, but several biological alternatives are being developed.
In this work, we evaluated nine biopesticides (HN, 11.5 ml/l ; Piol, 13.61 ml/l ; Limosain, 6.8 ml/l ; Biopoder, 12.6 ml/l ; HNN+, 7.56 ml/l ; HNN++, 7.56 ml/l ; Bangr-pougo (BP), 200 ml/l ; Bangr-kièta (BK), 200 ml/l ; Bangr-pougo (BP) formulated in powder, 10 g/l), available in the West African market, for their ability to control T. absoluta. We followed the IRAC022 (Insecticide Resistance Action Committee) methodology, consisting in leaf/egg dip bioassay, to compare both the ovicidal and the larvicidal activity of these biopesticides, at various concentrations of active ingredients.
We found, for each tested biopesticides, the larva lethal concentrations (LC) (8.2 - 41.14 ml/l) to be lower than those necessary to stop egg hatching (26.7 - 409.7 ml/l). Two products, both based on Azadirachta indica extracts and bark of Khaya senegalensis, showed high efficacy in reducing egg hatchability, at their recommended doses (200 ml/l and 10 g/l), with a calculated control failure likelihood (CFL) reaching 0%. These two products, together with a third one based on Mitracarpus scaber extracts, also showed the strongest larvicidal effects (CFL = 0%). All other tested biological insecticides showed significant efficiency but were found to be less effective at their recommended doses.
Because the leafminer has developed resistance to most of the synthetic insecticide available on the market, we recommend that a proper communication is made toward West African tomato producers to encourage them to use the most efficient biological products available.