Differences in Extent of Genetic Introgression Between SympatricCulex pipiensandCulex quinquefasciatus(Diptera: Culicidae) in California and South Africa

Abstract

Comparisons of five morphological characters, 12 enzyme electrophoresis profiles, and Wolbachia pipientis infection rates were used to characterize populations of members of the Culex pipiens L. complex in California and South Africa. In South Africa, male phallosome DV/D ratio, male maxillary palp index, branching of siphonal seta 1a, the enzyme locus Mdhp-1, and W. pipientis infection rates proved highly diagnostic for separating Culex quinquefasciatus from Cx. pipiens phenotypes. In Johannesburg, where sympatric members of the Cx. pipiens complex were analyzed as one population, a significant Wahlund Effect was observed in the enzyme loci such as Ao, 6-Pgdh, Mdh-2, and Pgm. In California, all populations of the Cx. pipiens complex were in Hardy Weinberg equilibrium at all polymorphic enzyme loci examined. Additionally, in California, all populations had similar W. pipientis infection rates and appeared morphologically identical (except for DV/D ratio, in extreme north and south). These findings indicate that in South Africa, Cx. pipiens and Cx. quinquefasciatus remain as genetically distinct populations and behave as separate species. Conversely, in California, there is considerable genetic introgression between Cx. pipiens and Cx. quinquefasciatus, and they behave as a single species.

Rapid Assays for Identification of Members of the Culex (Culex) Pipiens Complex, Their Hybrids, and Other Sibling Species (Diptera: Culicidae)

“…quinquefasciatus, as has been proposed. 13,16 We are currently performing additional analyses which include populations of Cx. p. pallens from China and northernmost Japan.…”

Phenotypic Variation among Culex pipiens Complex (Diptera: Culicidae) Populations from the Sacramento Valley, California: Horizontal and Vertical Transmission of West Nile Virus, Diapause Potential, Autogeny, and Host Selection

“…Genetic introgression between members of this complex in California, especially in the Central Valley, has made identification of populations using morphological and allozyme marker analysis 7,8 unreliable. 9 Culex pipiens and Cx. quinquefasciatus are competent vectors of WNV in California, although there is spatio-temporal variability.…”

Autogeny in Culex pipiens Complex Mosquitoes from the San Francisco Bay Area

“…In overlapping areas, the species have hybridized extensively. [8][9][10][11][12][13] The worldwide movement of these two species continues to this day as revealed by rapid expansion of insecticide resistance 14 and the recent invasion of remote locations such as the Galapagos Islands. 15 To complicate matters further, Cx.…”