Field-evolved resistance to chlorantraniliprole in the tomato pinworm Tuta absoluta: inheritance, cross-resistance profile, and metabolism

The tomato pinworm Tuta absoluta is currently the most important pest of tomatoes worldwide. Diamides are one of the few effective classes of insecticides in use for its management, but recent cases of very high resistance to these insecticides in field populations of this invasive pest species have been reported in Brazil and Europe. Herein, the resistance of T. absoluta to chlorantraniliprole was genetically and biochemically characterized. Concentration-mortality curves were estimated for parental (GBN-Sus and AMD-Sel), F-1, and backcross generations through the leaf-dipping method, which was also used in further bioassay-based experiments. Inheritance studies indicated that chlorantraniliprole resistance is monogenic, completely recessive, and autosomal. Dominance of chlorantraniliprole resistance was concentration dependent shifting to recessive as the insecticide concentration increased. In addition, concentrations above 0.4 mg chlorantraniliprole/L made resistance completely recessive. Esterases, glutathione S-transferases, and cytochrome P450-dependent monooxygenases are apparently not involved in the chlorantraniliprole resistance. Furthermore, the cross-resistance spectrum was restricted to the diamide insecticides flubendiamide and cyantraniliprole, suggesting that altered target site is the likely mechanism involved, in contrast with enhanced detoxification. Therefore, the interruption of chlorantraniliprole use against the tomato pinworm would be a useful management initiative for diamide resistance management for already resistant populations. Diamide use against this species in newly invaded areas should be carefully monitored to ascertain that diamide-resistant insects were not introduced and also to prevent rapid selection for diamide resistance and its potential spread to other areas.