Xie_2025_Pestic.Biochem.Physiol_215_106659

Bioinsecticides are commonly used to control Tuta absoluta, which predominantly feeds on tomatoes. However, excessive use of insecticides typically leads to resistance. Understanding the causes of resistance, inheritance patterns, and related fitness costs may assist in the regulation of resistance. A spinetoram-resistant strain (SPI-R) of T. absoluta was obtained by selective insecticide breeding for 20 generations (410.86-fold). Genetic analysis revealed that the resistance was polygenic, autosomal, and incompletely recessive with high heritability (h(2) = 0.36). Increased activity of three detoxification metabolic enzymes(cytochrome P450 monooxygenases, glutathione S-transferases, and carboxylesterase) played a primary role in resistance according to the synergist assay. SPI-R also exhibited fitness costs including extended larval stages and reduced adult longevity. These results provide useful insights for formulating practical recommendations for the effective use of spinetoram to control insecticide resistance in T. absoluta.