Cross-resistance and lack of fitness costs occurred in the cyantraniliprole-resistant oriental fruit fly

The oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most globally important insect pests that have evolved resistance to various groups of insecticides. To clarify the relationships between a novel and widely used anthranilic diamide insecticide (cyantraniliprole) and other regular insecticides used to effectively control B. dorsalis, its cross-resistance and fitness costs to various insecticides were determined. Bioassays with cyantraniliprole-resistant and cyantraniliprole-susceptible strains indicated moderate levels of cross-resistance to both of the spinosyn compounds, Spinosad (1.59-fold) and Spinetoram (1.54-fold), the organophosphate (Trichlorphon, 0.66-fold), and beta-cypermethrin (2.41-fold), one of the pyrethroids compounds. Most of the tested biological parameters of B. dorsalis were negatively affected by cyantraniliprole resistance. Compared with the susceptible strain, prolonged larval duration, higher pupa weight, longer timing of sexual maturation, were observed in the cyantraniliprole-resistant strain. Pupa duration, oviposition, and male remating inhibition on the fifth day were significantly lower for the cyantraniliprole-resistant strain than those of the susceptible strain. Moreover, there was no fitness costs associated with resistance to cyantraniliprole. Morderate levels of cross-resistance were observed between cyantraniliprole and four other selected insecticides (Spinosad, Spinetoram, Trichlorphon, and Beta-cypermethrin). However, the lack of fitness costs in the cyantraniliprole-resistant strain of B. dorsalis could promote the rapid development of resistance to cyantraniliprole. Thus, the results obtained here were useful for the application and resistance management of cyantraniliprole against B. dorsalis.