Cross-resistance and biochemical mechanism of resistance to cyantraniliprole in a near-isogenic line of whitefly Bemisia tabaci Mediterranean (Q biotype).

Bemisia tabaci, sweetpotato whitefly, is one notorious insect pest on a series of crops worldwide, and many populations show high resistance to various insecticides. The cyantraniliprole-resistant strain of B. tabaci SX-R (138.4-fold) was obtained by selections with an outdoor-collected cyantraniliprole resistant population. By crossing and repeated backcrossing to a susceptible MED-S strain, the trait of cyantraniliprole resistance from SX-R was moved into MED-S to establish one near-isogenic line (CYAN-R). MED-S and CYAN-R were utilized to build patterns of cross-resistance, CYAN-R strain exhibited 63.317-fold resistance to cyantraniliprole, but no cross-resistance to several other successfully commercialized chemical agents. After that significant inhibition of cyantraniliprole resistance by piperonyl butoxide (PBO) and increased cytochrome P450 (3.4-fold) were observed in CYAN-R strain, indicating putative involvement of P450 in detoxification. Furthermore, five published detoxification-related P450 genes in B. tabaci, CYP4C64, CYP6CM1, CYP6CX1, CYP6CX4, and CYP6DZ7 were selected and expression levels of them were measured for exploring mechanisms of cyantraniliprole resistance. Compare with MED-S, no significant overexpression of the five P450 genes was observed in the CYAN-R strain. Above results could be conductive to study on mechanism of cyantraniliprole resistance and will be very helpful for the management of whitefly.