GENETIC VARIATION IN
POPULATIONS OF CULEX PIPIENS FROM THE
NORTHEASTERN
Shaoming Huang, Goudarz Molaei and Theodore G.
Andreadis
The
ABSTRACT
Members of the Culex
pipiens complex have been regarded as
vectors of important arboviruses including West Nile virus. Recent studies
indicate considerable variation in the host-feeding behavior of Cx. pipiens
populations. Populations from the northeastern US have a very strong preference
for avian with occasional feeding on mammalian hosts including humans whereas
populations from other regions appear to have greater interactions with
mammals. In order to gain insights into the underlying mechanisms for these
apparent variations, we analyzed population structure of Cx. pipiens from the
northeastern, and examined genetic variation among individuals from Midwestern
US. In a comparative analysis with populations of neighboring states, New
Jersey, New York and Massachusetts, population structuring associated with
geographic distance were detected. In examining the
principally ornithophilic population of Cx.
pipiens with a relatively higher
inclination for mammalian hosts including humans from Chicago, Illinois, we did
not find significant genetic differentiation between specimens with avian- and
mammalian-derived blood meals. However, Cx.
pipiens with mammalian- (including
human-) derived blood meals had significantly higher proportion of hybrids from
the Cx. pipiens form molestus than did those with avian-derived blood
meals. By contrast, there were no significant differences in the proportion of
hybrids from Cx. quinquefasciatus. No temporal genetic variation was detected in
accordance with the observation that there was no apparent shift in blood
feeding from birds to mammals. Our results in conjunction with regional
host-feeding behavior suggest that the probability of genetic ancestry from Cx. pipiens
f. molestus may predispose mosquitoes to feed more readily on mammals, although
the genetic mechanisms are not known.