LAUSR

Abstract Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae) has become a serious economic pest of the malvaceae family in Pakistan. It is widely distributed in the world and is polyphagous. In this study, we investigated the toxicity of insecticides, insecticide resistance and its stability and cross-resistance in a field strain of O. hyalinipennis. The bioassays of all insecticides were performed by the leaf dip method. The toxicity of chlorfenapyr was significantly greater than that of bifenthrin, fipronil or emamectin benzoate (95% fiducial limits (FLs) did not overlap at LC50) when tested on a reference laboratory susceptible strain (Lab-PK). The toxicity of chlorfenapyr was significantly greater compared to bifenthrin when tested on a field population (Field-POP) and an unselected population (UNSEL-POP) whereas the toxicity of chlorfenapyr was significantly lower than that of triazophos when tested on a chlorfenapyr selected population at generation 7 (Chlorfenapyr-SEL (G7)). Chlorfenapyr toxicity was statistically similar (95% FLs overlap at LC90) to bifenthrin, triazophos, fipronil and emamectin benzoate when tested on Field-POP, UNSEL-POP and Chlorfenapyr-SEL (G7). A field population of O. hyalinipennis from Punjab, Pakistan showed resistance to chlorfenapyr (20.4-fold), bifenthrin (16.8-fold), triazophos (18.4-fold) but tolerance or low resistance was found to fipronil and emamectin benzoate, compared with the Lab-PK population. Bioassay at generation 6 (G6) showed that selection with chlorfenapyr gave a high resistance ratio compared with the Lab-PK population. The Chlorfenapyr-SEL population showed limited cross-resistance to bifenthrin, triazophos, fipronil, and emamectin benzoate. Stability results showed resistance to chlorfenapyr and triazophos was unstable while stable resistance was determined to bifenthrin, fipronil and emamectin benzoate. In this study, limited cross-resistance to the tested insecticides was found; stable and unstable resistance to Chlorfenapyr-SEL population gave valuable information regarding the management of O. hyalinipennis.