The tomato leafminer, Tuta absoluta, is one of the most destructive pests of tomato worldwide. Management of this pest is mainly based on chemical insecticides, but the reliance on insecticides is difficult to sustain. Thus, there is a need to develop pest management strategies that ensure at the same time both the production of high‐quality products and environmental sustainability with maximum consumer protection.
Scientists at Kuwait Institute for Scientific Research (Safat, Kuwait) have tested the efficacy of four biopesticides (Azadirachtin, Bacillus thuringiensis, Steinernema feltiae and Beauveria bassiana) individually and in combination against T. absoluta under laboratory and greenhouse conditions on tomato crop.
"When second instar larvae were exposed to tomato leaf discs treated with Azadirachtin (3 g/L), B. thuringiensis (0.5 g/L) or B. bassiana (1.5 g/L), 70%–86%, 55%–65%, and 45.5%–58.5% mortality was observed, respectively - the scientists explain - while Steinernema feltiae was the least effective biopesticide, with 26%–42% mortality".
In the greenhouse, pest infestation and fruits damaged were significantly lower on plants treated with Azadirachtin + B. thuringiensis or Azadirachtin + B. bassiana compared to plants treated with the same biopesticides alone. Azadirachtin + B. thuringiensis and Azadirachtin + B. bassiana resulted in 90% and 81% reduction in fruits damaged in the summer experiments, respectively, and 96% and 91% in winter. The most severe pest infestation was observed on plants treated with S. feltia.
"The results indicate that the biopesticides, except S. feltia, can contribute to T. absoluta control in greenhouse tomato crops. In particular, the highest level of pest control has been obtained by the combined use of Azadirachtin with B. thuringiensis or B. bassiana - the scientisst conclude - The study shows the potential for including these biopesticides in an overall sustainable integrated pest management programme for T. absoluta".
Source: Mustapha F. A. Jallow, Abdelhafiz A. Dahab, Mohammed S. Albaho, Vimala Y. Devi, 'Efficacy of some biorational insecticides against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) under laboratory and greenhouse conditions in Kuwait', 2019, Journal of Applied Entomology, Vol. 143 (3), pag. 187-195.