DISTRIBUTION OF MOSQUITOES IN NATIONAL PARK UNITS OF THE NORTHEASTERN UNITED STATES

Technical Report NPS/NER/NRTR--2006/050

Christine M. Lussier¹, Howard S. Ginsberg², and Roger A. LeBrun¹

¹Department of Plant Sciences
University of Rhode Island
Kingston, RI 02881

²USGS Patuxent Wildlife Research Center
Coastal Field Station Woodward Hall-PLS
University of Rhode Island
Kingston, RI 02881

July 2006

U.S. Department of the Interior
National Park Service
Northeast Region
Boston, Massachusetts

__________________________

EXECUTIVE SUMMARY

Mosquito species commonly involved in West Nile Virus (WNV) transmission in eastern North America include Culex pipiens, Cx. restuans, Cx. salinarius, and Aedes vexans. We surveyed mosquitoes at eight national park sites in the northeastern U.S., and developed surveillance recommendations based on a comparison of catches in CO₂-baited CDC miniature light traps and in gravid traps at the various parks.

Few national parks have mosquito surveillance programs and mosquito distribution within most parks is unknown. Adult mosquitoes were sampled using three types of traps: CO₂-baited CDC miniature light traps, gravid traps baited with an oak infusion, and gravid traps baited with a standard hay infusion. Also, mosquitoes that approached investigators while setting traps were collected. All specimens were identified and counted, and selected adults from the gravid traps were sent for viral testing.

Coquillettidia perturbans, an inefficient lab vector of WNV, was the most widely distributed species in CDC traps. Adults of this species were common at Acadia National Park, Saratoga National Historic Site, Minute Man National Historic Park, Cape Cod National Seashore, Roosevelt/Vanderbilt National Historic Site, and Delaware Water Gap National Recreation Area. Ae. vexans, a potential bridge vector of WNV, was common in Minute Man National Historic Park, Fire Island National Seashore, and Gateway National Recreation Area. Cx. salinarius, which has been implicated as an important bridge vector of WNV, was found at Fire Island National Seashore and Gateway National Recreation Area. Ae. sollicitans, also a potential bridge vector, was common at coastal parks with salt marsh habitat such as Acadia National Park, Fire Island National Seashore, and Gateway National Recreation Area. Gravid traps effectively caught Cx. pipiens and Cx. restuans, both of which are competent enzootic vectors of WNV. Cx. pipiens was common in Saratoga National Historic Site, Minute Man National Historic Park, Cape Cod National Seashore, Delaware Water Gap National Recreation Area, Fire Island National Seashore, and Gateway National Recreation Area. Cx. restuans was found in Saratoga National Historic Site, Minute Man National Historic Park, Cape Cod National Seashore, Roosevelt/Vanderbilt National Historic Site, Delaware Water Gap National Recreation Area, and Gateway National Recreation Area.

The results of this study suggest that of the parks sampled, conditions were most suitable for WNV activity at Gateway National Recreation Area and Fire Island National Seashore. Both of these parks had substantial populations of enzootic vectors along with abundant species that are potential bridge vectors. Minute Man National Historic Park also had populations of enzootic and potential bridge vectors. The most common possible bridge vector at most of the other parks was Cq. perturbans, which has had low vector competence in lab trials. Although epidemic activity of WNV cannot be ruled out at these parks, the likelihood appears considerably lower than for Gateway and Fire Island. The only WNV-positive sample (of 116 mosquito pools tested) was a pool from Gateway National Recreation Area that contained one specimen of Cx. pipiens.

We compared sampling methods, including CO₂-baited CDC Miniature Light Traps, gravid traps baited with hay infusion, gravid traps with oak leaf infusion, and aerial sampling of adult mosquitoes approaching investigators. CO₂-baited CDC traps captured the most mosquitoes and the greatest diversity of mosquito species. The species most commonly collected in CO₂-baited CDC traps were Ae. vexans, Ae. sollicitans, Cq. perturbans, Ae. canadensis, and Cx. salinarius.

Gravid traps baited with oak leaf infusion were the most effective at sampling Cx. pipiens and Cx. restuans. Gravid traps with different infusions shared 57.7% of the species collected, while the other sampling methods captured substantially different species. The species that was most commonly captured approaching investigators was also the most common species in CDC traps on only 39.0 % of trap nights. Therefore, CDC trap captures do not always directly reflect the species biting people at a given time and place.

______________________

The entire report is available to view or download in PDF file format. Using PDF files requires the free Adobe Acrobat Reader. If you do not already have it installed on your computer, you may download it now. Download Reader.

To download a pdf file, click on this icon in the toolbar of the pdf window: . This will allow you to save the file on your computer. If you want to copy or print only a small part of the saved file, click on this icon to select the desired text:.