Reproduced from the Proceedings of the 74th Annual Meeting of the NJMCA. Please use the following citation when referring to this article:
Crans, W. J, and McCuiston, L. J. 1987. Rare New Jersey mosquito species collected in 1986. Proc. N. J. Mosquito Control Assoc. pp. 89-94.
(See also Morphological Comparisons of several Aedes/Ochlerotatus species)
WAYNE J. CRANS AND LINDA J. McCUISTON
Mosquito Research & Control, P.O. Box 231 Cook College New Brunswick, N.J. 08903
INTRODUCTION: New Jersey has 60 mosquito species on its most recent checklist but less than 30 are routinely monitored by the surveillance techniques employed by State and County mosquito control agencies. Some, like the Northern Aedes, are restricted to a very small geographic area of the state and appear only for a short period during the early season. Others are so uncommon that no collection records can be documented beyond the original report. In 1986, a number of relatively rare species were brought to the attention of Experiment Station personnel. This paper is intended to document the collections, review the biology of the various species and report the events that led to their detection.
Culex tarsalis: Culex tarsalis, an important pest and vector species in the western United States, was originally detected in New Jersey when a single adult female was found in a light trap collection at Beach Haven, Ocean County, in 1975 (Lesser et al. 1977). The species reappeared along the New Jersey coast in 1977 and a special surveillance effort located 9 specimens in 3 coastal counties of the state (Crans et al 1979) Data suggested that Cx. tarsalis was breeding at low levels in freshwater impoundments constructed to eliminate the salt marsh mosquito, Aedes sollicitans. The survey also revealed that Culex salinariuswas the dominant mosquito species in the areas that were reclaimed from salt water intrusion. No collections were reported in the years following the 1979 investigation. Data indicated that the species was unable to compete with Cx. salinarius, a mosquito that has exploited freshwater impoundments throughout the coastal areas of the state (Slaff and Crans 1982).
In 1986, Mr. Herman Ehrenberg, of the Bergen County Mosquito Extermination Commission collected 2 adult female Cx. tarsalis the Hackensack Meadowlands in the New York-New Jersey metropolitan area. The first collection was made at Lyndhurst, Bergen County on July 16. The second specimen was taken at Kearny, Hudson County on September 11. Both of the specimens were collected in pigeon-baited traps designed to sample Culex mosquitoes in an urban habitat (Ehrenberg 1966, Downing and Crans 1977).
The appearance of Cx. tarsalis in the Meadowlands area raises important questions regarding the future of this opportunistic species in New Jersey. The Meadowlands area was once grossly polluted, excluding all but the most pollution tolerant mosquito species. Pressures from environmental groups have improved water quality in recent years the flora and fauna are currently in a state of transition. No data are available to measure the potential for Cx. tarsalis under the conditions offered by the Meadowlands habitat. Continued surveillance will be conducted to determine if Cx. tarsalis can compete with native species in an urban focus.
Aedes thibaulti: Aedes thibaulti is a mosquito species with a patchy distribution the eastern United States. The mosquito is primarily southern in its distribution but isolated records have been reported as far north Ontario, Canada (Darsie and Ward 1981). Lake & Doll (1961) located larvae in Delaware and predicted that the species would eventually be found in southern New Jersey. The species were not detected in New Jersey until 1983, when McNelly (1984) located a number of breeding sites in Cape May County. Larvae were collected primarily from dark recesses that held water beneath uprooted trees in dense red maple swamps. No records have been confirmed outside of Cape May Count since the original report.
During the summer of 1986, Ae. thibaulti adults were collected from 2 new locations in the State. All of the collections were taken in CD light traps that were baited with a carbon dioxide source. Two female were collected in a trap at the Turtle Run Campground in Burlington County on June 24. An additional specimen was taken at the same sit the following week. On June 27, 7 specimens were taken in a trap operated in the Glassboro Wildlife Management Area in Gloucester County. One additional specimen was collected from the management site on July 11. Both of the collection sites were surrounded by habitat similar to that described by McNelly (1984). Data suggest that the species is probably more widespread in New Jersey than current record indicate.
Culex erraticus: Culex erraticus was first reported from New Jersey by Crans (1970). The original record was based on adult specimens collected simultaneously by the Cape May County Mosquito Extermination Commission and the NJ State Department of Health. Although the species has reappeared on several occasions near the original collection site, no documentation of Cx. erraticus can be found outside of Cape May County. During the summer of 1986, Cx. erraticus was common in resting boxes at a number of locations in southern New Jersey.
Table 1 lists Cx. erraticus that were collected during the 1986 Experiment Station surveillance program for eastern equine encephalitis virus. A total of 267 specimens were taken from 6 sites in 4 separate counties.
TABLE 1. Geographic distribution of Culex erraticus in New Jersey based on 1986 surveillance data for eastern equine encephalitis virus
County, Area: Number Collected
Table 2 lists the seasonal distribution of Cx. erraticus, according to the surveillance data. Data suggest that the species does not appear until late in July and reaches greatest numbers during the latter part of the mosquito season. All but one of the 267 specimens were collected in resting boxes, a surveillance tool that appears to be especially attractive to this little known mosquito species.
TABLE 2. Seasonal distribution of Culex erraticus in New Jersey based on 1986 surveillance data for eastern equine encephalitis virus.
Month: Number Collected
Aedes atropalpus: Thomas J. Headlee listed Aedes atropalpus in his 1921 Experiment Station Bulletin (Headlee 1921) with the notation that no specimens had yet been detected in New Jersey. The mosquito had, apparently, been collected from rock pools in both Maine and Maryland and Dr. Headlee was quite certain that the species would eventually be found "along the shores of the Delaware River near the Water Gap". Twenty-four years later, Dr. Headlee included Ae. atropalpus in his book (Headlee 1945) with the notation that 113 adult specimens had been trapped but no one had yet encountered the larvae. Dr. Headlee, again, pointed out that the species "will be almost certainly found ... along the shores of the Delaware River in Warren County and other streams in the rocky section of the State".
From 1945 to the present no documentation can be found to indicate that the species was ever collected in the larval stage. Isolated records do appear among county light trap data at the Experiment Station and a single pinned specimen was found in an old collection box that probably dates back to Headlee's time.
On September 23, 1985, Christine Musa (then Biologist of the Warren County Mosquito Extermination Commission) brought a single adult Ae. atropalpus to the Experiment Station for confirmation of identification. The specimen had been collected in the Commission office by the Secretary, who had no idea that she was providing information that would ultimately prove Headlee correct.
A literature search revealed that, although Ae. atropalpus is most frequently associated with rock pools that fill from overflowing stream water, the species has been reported from artificial containers (Means 1979). Stromm et al. (1960), cited airplane tires as a major breeding source for Ae. atropalpus near San Antonio, Texas. Armed with that information, the Warren County Mosquito Commission conducted a larval search. In May, 1986, Christine Musa located Ae. atropalpus larvae in tires that had been discarded along the Delaware River just south of Belvidere in Warren County.
Beginning in June, tires at the disposal site were sampled on a weekly basis and Ae. atropalpus larvae were found until the end of August. CDC light traps collected adult specimens on a regular basis and bite counts revealed host-seeking Ae. atropalpus mixed with Ae. triseriatus in the biting population.
DISCUSSION: Data from the 1986 season suggest that the "rare" mosquito species on New Jersey's checklist may not be as rare as surveillance data indicate. Dependence upon light traps as a surveillance tool may be a contributing factor. A number of the mosquito species listed as "rare" are cryptic in the adult stage, with common species routinely represented in light trap collections. In most cases, the larvae provide a much better indicator for species distribution. Ae. thibaulti closely resembles Aedes aurifer in the adult stage, a common early season mosquito in the northern portion of New Jersey. In the southern district, the adults resemble Aedes sticticus, a species that often is reported in light traps during the early season. Cx. erraticus superficially resembles Culex territans and may be missed in areas where the two species occupy similar habitat. Data also suggest that Cx. erraticus rarely enters light traps but is highly attracted to resting boxes, a collection device that is not widely used as a surveillance tool. Ae. atropalpus closely resembles Aedes canadensis, a very common mosquito throughout the state. Specimens collected in light traps could easily be confused with the more common, cryptic pest species.
Available data suggest that light traps should not be relied upon as a sole surveillance tool. Accelerated larval surveillance and utilization of alternative adult collection methods may well lead to additional records of "rare" and relatively rare mosquito species over a wider geographic area of New Jersey.
ACKNOWLEDGMENTS: New Jersey Agricultural Experiment Station Publication No. E-40101-01-87 supported by the U.S. Hatch Act with partial support from the New Jersey State Mosquito Control Commission.