Caribbean fruit fly, Anastrepha suspensa, has been a major insect pest in subtropical and tropical fruit crop including citrus, guava, srinam cherry, loquat etc., in USA and many countries in central America and Caribbean islands. In market, infested fruits by this pest will not be accepted that in turn resulted in millions of dollars loss. Currently, management of this pest relies on the baited traps incorporating food and insecticides, however, continuous use of insecticide will pose negative impact such as environmental contamination, increasing pesticide resistance, and affect non-target organisms. In this presentation, the resistance of methomyl-resistant and susceptible strains of A. suspensa have been evaluated with four insecticides from different classes, including methomyl, Naled, cyfluthrin, and Spinosad. The results showed that no significant cross resistance of susceptible flies was found among all tested insecticides. The LD50s of methomyl-resistant flies to Naled, cyfluthrin, and spinosad were not significantly different from those of susceptible flies. From 2021 to 2024, the resistance ratio of field collected A. suspensa has been 5.5, 6.1, 8, and 9 for organophosphate (< 10, i.e. methomyl), indicating a mild range of resistance developed. Meanwhile, synergists PBO and DEM were also evaluated to determine the enzyme activity on toxicity of A. suspensa to better understanding the chemical response of resistant A. suspensa. The information in this research is useful to develop biorational management for A. suspensa.