Characterization of genetic basis and realized heritability of bifenthrin-resistance selected in dusky cotton bug, Oxycarenus hyalinipennis (Costa) (Hemiptera: Lygaeidae) in Pakistan

Abstract

Dusky cotton bug, Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae) is a major pest of cotton crop across various regions in the world, and has developed resistance to a number of insecticides including bifenthrin. In the current study, we evaluated the genetics and realized heritability (h2) of bifenthrin resistance following selection of O. hyalinipennis in the laboratory for 15 generations. The selected population of O. hyalinipennis had a resistance ratio of 554.21-fold as compared to a laboratory susceptible population. Toxicity data of reciprocal crosses F1 and F1’ revealed that bifenthrin resistance was inherited as an autosomal trait and no maternal influence was involved. The degree of dominance (DLC) values, 0.68 and 0.81 for F1 and F1’, respectively, revealed that incompletely dominant genes were governing the bifenthrin resistance in O. hyalinipennis. Resistance to bifenthrin also shifted from completely dominant (DML = 0.95) to fully recessive (DML = 0.08) trait upon changing the concentrations of bifenthrin from 165.25 ppm to 2500 ppm, respectively. The chi-square analysis of monogenic model in both back-crosses, BC1 (F1♀ × S♂) and BC2 (F1♀ × R♂) resulted in rejection of the hypothesis of monogenic resistance, which indicated that multiple factors were involved in controlling bifenthrin resistance. The estimated value of realized heritability (h2) for bifenthrin resistance was 0.09. Selection of O. hyalinipennis with bifenthrin for 15 generations induced a high resistance to bifenthrin that was autosomal, incompletely dominant and polygenic in nature. A low heritability value revealed that bifenthrin resistance could likely develop in the field but at much slower pace. These results have important implications for bifenthrin resistance management in O. hyalinipennis.