Cross-resistance to several new pesticedes exhibited by abamectin-and tebufenozide-resistant Plutella xylostella

With the susceptible strain as control,the resistance strains of Plutella xylostella to tebufenozide ( Teb-R) and to abamectin ( Aba-R) developed in laboratory were surveyed for their cross-resistance to several new insecticides. Toxicity bioassay showed that Teb-R strain ( resistance ratio,RR 185. 5) exhibited a moderate level of cross-resistance to abamectin ( RR 41. 0) , a low level of cross-resistance to indoxacarb ( RR 11. 4) and chlorfenapyr ( RR 5. 3) ,but no significant cross-resistance to spinosad ( RR 1. 7) and chlorantraniliprole ( RR 1. 4) . When Teb-R strain was subjected to the followed selection with abamectin for 39 generations,the resulted Aba-R strain ( RR 593. 8) exhibited a moderate level of cross-resistance to indoxacarb ( RR 12. 3) and a low level of cross-resistance to spinosad ( RR 7. 9) ,but no significant cross-resistance to chlorfenapyr ( RR 2. 7) and chlorantraniliprole ( RR 0. 9) . Its corresponding resistance to tebufenozide decreased from 185. 5 times to 28. 0 times,which implied no cross-resistance to tebufenozide. According to these results above,it was suggested that spinosad and chlorantraniliprole could be used as substitutes of tebufenozide to control P. xylostella. But when the resistance to tebufenozide developed,abamectin, chlorfenapyr and indoxacarb could not be used as alternatives. Chlorfenapyr,tebufenozide and chlorantraniliprole could be used to control P. xylostella which had developed resistance to abamectin,but spinosad and indoxacarb should not be used.