Attempted insertion of a recessive autosomal gene into a semi-isolated population of Culex tarsalis (Diptera: Culicidae).

Abstract

A total of 158,957 adult Culex tarsalis mosquitoes carrying a recessive autosomal eye-pigment mutant, carmine eye (car) , were released in the spring of 1982 at a semi-isolated area in the arid foothills of Kern County, California, USA. The persistence of the released genotype was monitored by examining the progeny of field-mated females from the target population, backcrossing field males to homozygous car laboratory females and examining their progeny, and by inspecting field-collected immatures for homozygous car larvae. In addition, males reared from field-collected and phenotypically wild-type larvae were backcrossed to car females during the spring of 1983. Carmine eye phenotypic frequencies declined rapidly following the vernal rise of the target population; however, males heterozygous for car were recovered throughout the summer of 1982 and during the spring of 1983. Assortative swarming and mating behavior among the released genotype may have impeded the insertion of the released gene into the target population gene pool. Reduced larval fitness and a high immigration rate may have contributed to the failure of the released genome to be maintained at a high level.