Culex salinarius
Coquillett
by Wayne J. Crans, Rutgers University
Subgenus :
Culex
Type of Life Cycle :
Model for Culex salinarius
Type, multivoltine Culex with
some salt tolerance
Typical Habitat :
Brackish water swamps
Larvae Present :
Late Spring to Fall
Head Hairs:
Upper:
Multiple
Lower :
Multiple
Antenna:
Length:
Shorter than head, constricted
Tuft:
Large, multiple, inserted at constriction
Abdominal Hairs (Segments
III-VI) : 2-2-2-2
(Possibly triple on some segments)
Comb Scales :
Many scales in a patch
Siphon:
Index: 6.5
- 7.0
Tufts:
4-5, paired 2-4 branched tufts inserted beyond pecten
Pecten:
10-16 teeth on basal 1/4 of siphon
Anal Segment:
Saddle:
Complete ring
Precratal
tufts: None
Other:
1) Gill length can be variable;
2) Siphonal Index fairly diagnostic
GEOGRAPHIC DISTRIBUTION:
Culex salinarius
has a distribution that extends over most of the eastern United States
from Maine south to southern Florida, west to central Texas and north to
the lower Great Lakes region.
Relict populations have been reported in the west from New
Mexico, Wyoming and Idaho.
The mosquito is susceptible to extreme cold and is frequently killed off
by severe winters in the northern limits of its range.
Repopulation of northern habitats is thought to take place by
migration where the species persists until the next killing temperatures
are encountered.
Culex salinarius has been
reported from every county in New Jersey but reaches greatest abundance
in coastal areas near freshwater impoundments.
SEASONAL DISTRIBUTION:
Culex salinarius
has a life cycle similar to
Culex pipiens with several
notable exceptions. The
mosquito enters hibernation in late fall but does not congregate in
dwellings like the common House Mosquito.
Hibernation is thought to take place in natural shelters with
muskrat huts and animal burrows cited as likely overwintering habitat.
Culex salinarius does
not produce large amounts of fat body and does not diapause in a torpor
like Cx. pipiens.
Adult Cx. salinarius
host seek well into the fall and often pester hunters in duck blinds
during the month of November.
The females can become active at the first sign of mild weather
and may actively seek a blood meal during the January thaw. Light traps
operated year round in Ocean Co. NJ captured a least 1 female
Cx. salinarius every month
during winter. The species
is multivoltine, like most Culex,
and populations build gradually from spring through summer.
There is generally a late season population peak in the fall
which persists until cold weather forces the adults into hibernation.
Larval populations build markedly toward the end of summer and
larvae are frequently found in atypical habitats late in the season.
LARVAL HABITAT:
Culex salinarius
is often referred to as the “Salt Marsh
Culex” but larvae rarely
occur in numbers on the open salt marsh.
The mosquito does have salt tolerance but is capable of breeding
in purely fresh water. The
larvae are particularly abundant in freshwater impoundments, especially
impoundments where salt marsh habitat has been reclaimed through dyking
and flooding from upland runoff.
Culex salinarius
populations peak immediately after flooding because the rotting
saltmarsh vegetation creates an infusion that functions as an
oviposition attractant.
Virtually any freshwater habitat with dying vegetation can support
Cx. salinarius larvae.
In coastal areas, the mosquito frequently invades pools of open
water in Atlantic White Cedar swamps late in the season directly above
the subterranean crypts that support
Culiseta melanura.
When Cx. salinarius
does occur on the salt marsh it is generally limited to the upper edges
where brackish, rather than saline conditions are found.
Flooded stands of
Phragmites frequently produce
Cx. salinarius in numbers.
Roadside ditches, moderately polluted groundwater and artificial
containers provide secondary larval habitat, particularly at inland foci
where the species is less abundant.
COMMON ASSOCIATE SPECIES:
An.
bradleyi, Cx. restuans, Ae. cantator
LARVAL COLLECTION:
Culex salinarius larvae can
usually be collected in numbers from densely vegetated areas of
freshwater impoundments.
This is a permanent water breeder that reaches greatest abundance in
habitats that have remained flooded all summer long.
Larval populations are usually highest late in the summer in
areas devoid of predacious fish.
Collection may be difficult because the species is frequently
associated with unstable substrates.
Permanently flooded dredge spoil sites along the Delaware River
produce huge populations of this species but are virtually impossible to
sample over most of their area.
LARVAL IDENTIFICATION:
Culex salinarius
is fairly easy to recognize in the larval stage because of the
exceptionally long, thin air tube.
The species superficially resembles
Culiseta melanura but usually
occurs in very different habitat.
Under the microscope, the comb scales of
Cx. salinarius occur as a
patch and are very different from the barred comb scales of
Cs. melanura.
The scattered siphonal tufts of
Cx. salinarius also
distinguish it from either Cs.
melanura or Cx. territans.
Culex salinarius
closely resembles Cx. pipiens
and may be collected together with that species.
Accurate measurement of siphonal index is the best method of
separating these 2 similar species.
REPRESENTATIVE COLLECTION
RECORDS
Northern
New Jersey
Location:
Hackensack Meadowlands, Bergen Co.
Date:
August 3
Habitat:
Semi-polluted Freshwater Impoundment
Instar :
All instars
Southern
New Jersey
Location:
Canton Drain, Salem Co.
Date
July 28
Habitat :
Freshwater Impoundment
Instar
: All instars
IMPORTANCE:
Culex salinarius
is a mosquito species that accepts birds as well as mammals.
As a result, it has been incriminated as a potential bridge
vector of the encephalitis viruses.
Virus isolations have been made from wild populations but are a
fairly rare occurrence.
Laboratory studies suggest that the mosquito has an extremely high
threshold of infection and probably only functions as a secondary vector
during epizootic episodes.
Culex salinarius can be a
severe biting pest and readily enters houses to find a blood meal.
Culex salinarius can
occur in unbelievably high numbers in coastal areas where suitable
habitat is common. Unlike
Aedes sollicitans, this
species rarely causes
nuisance during daylight hours.
Hugh swarms have been reported at twilight near brackish water
habitat when the species emerges from its daytime resting sites in
cattail and Phragmites.
Much of the adult control directed toward
Aedes sollicitans in salt
marsh areas help manage pest populations of this species as well.
This webpage was begun on 7
July 1996 and last updated on 1 June
2010
