Possible Pleiotropism of a Gene Conferring Resistance to DDT, DDT Analogs, and Pyrethins in the House Fly and Culex tarsalis124

Abstract

A strain of house flies. Musca domestica L., possessing the third chromosomal DDT resistance gene kdr-O (knockdown-resistance-Orlando) was tolerant to several DDT analogs, to pyrethrins, and to pyrethins: piperonyl butoxid mixtures. When DDT resistance due to kdr-O was introduced by crossing over into susceptible strains possessing third chromosomal visible mutants, resistance to pyrethrins: piperonyl butoxide and to the DDT analogs also was introduced. Conversely, introduction of resistance to pyrethrins: piperonyl butoxide into a susceptible strain possessing a third chromosomal marker resulted in a strain resistant to DDT and DDT analogs. Thus, resistance to these insecticides was inseparable, and the gene kdr-O apparently confers resistance to DDT, DDT analogs, and pyrethrins: piperonyl butoxide. A strain of Culex tarsalis Coquillet, which possessed a kdr-O-like DDT resistance, was shown to be resistant to pyrethrins and pyrethrins: piperonyl butoxide mixtures. Breeding experiments demonstrated that resistance to DDT and pyrethrins in C. tarsalis were genetically linked. These results suggest pleiotropy in that kdr-O in the house fly confers resistance not only to DDT but to DDT analogs and pyrethrins. Resistance to DDT and pyrethrins in C. tarsalis is possibly controlled also by a similar mechanism.