Study of Synergism, Antagonism, and Resistance Mechanisms in Insecticide-Resistant Oxycarenus hyalinipennis (Hemiptera: Lygaeidae).

Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae) is an economic and key pest of the Malvaceae family widely distributed in the world. Significant field resistance to cypermethrin (26.69-fold), chlorpyrifos (32.60-fold), methomyl (10.87), acetamiprid (20.63-fold), fipronil (5.84-fold), and spirotetramat (116.02-fold) has been reported. Cypermethrin combined with methomyl and spirotetramat, methomyl with spirotetramat, acetamiprid with spirotetramat, and fipronil with spirotetramat had synergistic effects (combination index, (CI) in a laboratory population of O. hyalinipennis named Lab-PK. Methomyl combined with acetamiprid and acetamiprid with fipronil had synergistic effects on O. hyalinipennis in a field in Multan named Field-POP. Cypermethrin combined with methomyl and spirotetramat; chlorpyrifos with methomyl, acetamiprid, and spirotetramat; methomyl with acetamiprid and spirotetramat; and fipronil with spirotetramat also had synergistic effects on O. hyalinipennis in Field-POP. Enzyme inhibitors piperonyl butoxide and S,S,S-tri-n-butyl phosphorotrithioate significantly increased the toxicity of chlorpyrifos, methomyl, acetamiprid, and spirotetramat to O. hyalinipennis in Field-POP, suggesting a monooxygenase- and esterase-based resistance mechanism. However, fipronil did not synergize with PBO and DEF. This study suggests that insecticide mixtures showing synergism must be determined for insecticide resistance management and other strategies such as rotations, mosaics, and cultural control should also be considered for the management of O. hyalinipennis.