| Summary: | Tomato pinworm, <i>Tuta absoluta</i> (Meyrick) (Lepidoptera: Gelechiidae) is the major pest of tomato crops in Pakistan. Insecticides are commonly used for the management of this insect-pest. To develop a better insecticide resistance management strategy and evaluate the risk of resistance evolution, a field collected population of the tomato pinworm was selected with flubendiamide in the laboratory. We investigated the genetics of flubendiamide resistance and concentration-mortality response to other insecticides by selecting a field strain of tomato pinworm with commercial flubendiamide formulation. <i>Tuta absoluta</i> was reciprocally crossed with resistant strain (Fluben-R) and was selected up to 13 generations, while F<sub>1</sub> progeny was back-crossed with resistant parent (Fluben-R). The results of LC<sub>50</sub> and Resistance Ratio (RR) demonstrated a higher resistance developed in field and laboratory-selected strains (G<sub>2</sub> and G<sub>13</sub>, respectively). Field-collected and laboratory-selected (Fluben-R) strains demonstrated higher intensity of concentration-mortality response against chlorantraniliprole, thiamethoxam, permethrin, abamectin and tebufenozide compared to susceptible ones. Based on the overlapping of 95% FL, it demonstrated significant differences, revealing that it was not sex linked (autosomal) with no maternal effects. The backcross analysis of the F<sub>1</sub>× resistant parent resulting in significant differences at all concentrations suggests that resistance is controlled by more than one factor; the null hypothesis was rejected and inheritance was under polygenic control. Resistance progression from 38 to 550 folds demonstrated that <i>T. absoluta</i> can develop a higher level of resistance to flubendiamide. Concentration-mortality response experiments demonstrated that the LC<sub>50</sub> of some tested insecticides was higher for field-collected and laboratory-selected strains, suggesting that resistance mechanisms should be studied at a molecular level for better understanding. These results could be helpful to design resistance management strategies against the tomato pinworm.
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