Biology and Ecology of the Anopheles Quadrimaculatus Sibling Species Complex in Louisiana.

Abstract

A polymerase chain reaction method for identifying individuals in the Anopheles quadrimaculatus Say sibling species complex was validated for wild mosquitoes from Louisiana and Mississippi. This method distinguished An. quadrimaculatus species A, B, C, and D by detecting species-specific differences in the 2nd internal transcribed spacer of ribosomal DNA and was 100% specific and 95% sensitive. A polymerase chain reaction assay that detects differences in the second internal transcribed spacer of ribosomal DNA was tested for its usefulness in identifying all immature stages of two representatives in the An. quadrimaculatus sibling species complex. The technique was successful in amplifying DNA from eggs, 1st through 4th instars, and pupae of An. quadrimaculatus Say and An. inundatus Reinert. Attempts were made to colonize four of the five sibling species of the Quadrimaculatus Complex. Field-collected mosquitoes were brought into the laboratory to use as starting material for colonies. No colonies were established during this study. The approach taken for this research was too broad and a better approach would be to spend more time on one of the species and study a select, small number of natural populations. Sixteen larval habitats of sibling species of An. quadrimaculatus were characterized during 1997--98. Larval mosquitoes were identified using PCR. Habitat descriptions were made along with water analysis for inorganic ions. Anopheles quadrimaculatus Say was present in fifteen of the sites. Anopheles smaragdinus larvae were not collected from any site. Anopheles inundatus was the only species collected from one habitat, and was found in association with An. quadrimaculatus at another site. Anopheles maverlius was collected along with An. quadrimaculatus from one larval habitat. The water analysis from the different habitats could not be statistically compared due to a lack of locating a larger number of sites with species other than An. quadrimaculatus. Sixty-two mosquitoes were tested for the presence of the intracellular parasite Wolbachia pipientis which causes cytoplasmic incompatibility in some species of insects. Using an established PCR protocol, the rickettsia was not detected in any of the specimens.