Analysing resistance of different Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) strains to abamectin insecticide

Objective: Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), tomato leafminer, is an oligophagous insect. Larvae of T. absoluta can destroy especially tomato plants which lead to important yield loss in this economically valuable crop. Chemical control through insecticides has been a main method of controlling it in farming areas all over the world. However, continues application of certain registered insecticide such as abamectin might lead to resistance development in T. absoluta. The aim of this study was to monitor resistance status of abamectin insecticide and analyse resistance mechanisms of this insecticide in T. absoluta field populations from three districts of Turkey by using bioassay and biochemical methods. Methods: Bioassays and Biochemical assays. Results: Bioassay results showed that while Adana and Antalya strain of T. absoluta showed low resistance (3.03and 2.3-fold) to abamectin insecticide, Ankara strain of T. absoluta was not resistant to abamectin (1.31-fold). Biochemical analysis displayed that CYP450-PNOD activities showed 2.55 and 1.95-fold increase compared to susceptible population in Adana and Antalya field populations, respectively. Furthermore, GST-CDNB activities showed statistically significant (p<0.05) 1.3-fold increase only in Adana population. Although EST-α-NA activities showed 3.41-fold increase only in Ankara field population, this field population did not display a significant resistancy to abamectin. Conclusion: Consequently, cytochrome P450 monooxygenase enzymes seemed to have a major role in abamectin resistance development in field populations of T. absoluta from Turkey. In addition, GSTs possibly have supportive role such as reducing oxidative stress that developed during metabolism of abamectin in resistant field populations of T. absoluta.