Culex pipiens sensu lato in California: a complex within a complex?

Area of Science:

• Entomology
• Genetics
• Vector-borne disease ecology

Background:

• Culex pipiens sensu lato mosquitoes are significant nuisance pests and vectors of West Nile virus in California.
• Understanding the complex population structure and biologies of these mosquitoes remains a challenge for effective control and disease management.

Purpose of the Study:

• To investigate the population structure and genetic diversity of Culex pipiens sensu lato in California.
• To identify the presence and distribution of specific subspecies, such as Cx. p. molestus.
• To assess the congruence between morphological and molecular identification methods.

Main Methods:

• Microsatellite marker analysis for population structure clustering.
• Ace 2 gene sequencing for subspecies identification.
• Morphological examination of male genitalia.
• Polymerase chain reaction (PCR) diagnostic assays.

Main Results:

• Extensive population structuring was observed in central California, exceeding expectations based on known species and hybrids.
• Evidence for the presence of Culex pipiens molestus was found in various above and below-ground locations.
• Inconsistencies between male genitalia morphology and PCR-based identification were noted.
• High heterozygosity for pyrethroid resistance was detected across different times and locations.

Conclusions:

• The population structure of Culex pipiens sensu lato in California is highly complex and not fully explained by current concepts.
• The presence of Cx. p. molestus and genetic complexities challenge existing identification and control strategies.
• Further research is needed to refine identification methods and develop effective management approaches for these complex mosquito populations.