Cross-resistance of Cypermethrin-resistant Blattella germanica to Chemical Insecticides

Objective To determine the cross resistance of cypermethrin resistant Blattella germanica to 5 common chemical insecticides. Methods The cross resistance of Blattella germanica with permanent cypermethrin resistance to 3 pyrethroids (deltamethrin, permethrin, tetramethrin) and 2 non pyrethroids insecticides i.e. propoxur and DDVP were determined with a liquid film continuous exposure procedure. Results Cypermethrin resistant Blattella germanica showed cross resistance to 3 pyrethoids, with the resistance indices of 3.11 , 3.67 and 3.35 respectively; and have no cross resistance to other two non pyrethroids insecticides. Conclusion The insecticides should be rationally used in the process of chemical controls,i.e. insecticides with different action targets should be used alternatively,to avoid the development of cross-resistance.