Journal of the American Mosquito Control Association, 2O(2):lO5-lO9,2OO4 Copyrighi @ 2OO4 by the American Mosquito Control Association' Inc'

DISTRIBUTION OF OCHLEROTATUS TOGOI ALONG THE PACIFIC COAST OF

WILLIAM J. SAMES,I WLLIAM E, HERMAN,I DAVID A. FLORIN' ENN FRANCIS A. MALONEYI

ABSTRACT. Before this study, the mosquito Ochlerotatus (Finlaya) togoi (-theobald) had been reported from only 2 locations within the continental Unitid States, both of which were documented in Washington State. This study used active and passive surveillance to determine the current distribution of Oc. toSoi along the Pacific Coast of Washington. Results of the study show that small, but stable, populations of Oc. togoi exist in the northern San Juan Island region of Puget Sound. Geological formations in this region are conducive to rock holes and support populations of Oc. togoi. No members of Oc. togoi were found on the southwestern Wash- ington coast, the coast of the Olympic Peninsula, or in the lower Puget Sound.

KEY WOR"DS Ochlerotatus rogoi, mosquito, Washington, San Juan Islands, distribution

INTRODUCTION if it was adapting to any new habitats (e.g., artificial containers or alternate natural habitats to rock Ochlerotatus togoi (Theobald) is a well-known holes). mosquito species of coastal Asia including Russia, As a secondary objective, we wanted to obtain Japan, China, Korea, Malaysia, Thailand, and many the distribution of this mosquito in support of West of the northwestem Pacific islands (LaCasse and Nile virus (WN) surveillance efforts in Washington. Yamaguti 1948, Tanaka et al. 1979, Sota et al. In Asia, Oc. togoi is known as a vector of Japanese 1995). This species breeds in rock holes just above B encephalitis, as well as Brugian and Bancroftian the high-tide line and may be found in freshwater filariasis. Japanese B encephalitis and WN are both or salt water. LaCasse and Yamaguti (1948) and categorized as flaviviruses, and although Oc. togoi Shestakov (1961) discussed the possibility of 2 ir.- is already known to be a competent vector of Jap- distinguishable forms of Oc. togoi, I that inhabits anese B encephalitis, further evaluation of this spe- artificial containers and another that inhabits tidal cies will be required to determine its ability to vec- rock holes. Trimble (1984) searched to no avail for tor WN. If Oc. togoi becomes important as a WN Oc. togoi in artificial containers along the coast of vector, then this study will show which areas of British Columbia, Canada, and concluded that the Washington may be affected and will provide help- rock-hole form must be the one inhabiting North America. ful information during the development of control strategies. Belton (1980) and Trimble and Wellington (1979) provided personal information related to the lst potential finding of Oc. togoi in North America, MATERIALS AND METHODS and it is still unknown whether this species was introduced via trade ships or whether it was endem- This study was conducted from Aprll 2OO2 ic to North America. However, it was not until Soll- through May 2OO3by using passive and active sur- ers-Riedel (1971) reported the discovery of Oc. to- veillance methods. Based on the reports that Oc. goi in British Columbia that North American togoi may utilize artificial containers (LaCasse and studies began on this species. As part of the North Yamaguti 1948, Shestakov 1961), standard black American studies, Belton (1980) reported Oc. togoi plastic ovitraps with red velour oviposition strips from Rosario Beach State Park on Fidalgo Island, were used to provide an oviposition site for gravid Skagit County, Washington. Later, Belton and Bel- female Oc. togoi. Each trap was baited with a l:l ton (1990) reported Oc. togoi from Rocky (=Rock) mix of freshwater with local seawater. Two to 3 Bay, San Juan Island, San Juan County, Washing- ovitraps were placed at 37 locations from Drayton ton. Since then, no documented findings of natural Harbor near Blaine, WA, southward along the populations of this species have been reported in shores of Puget Sound, around the Olympic Pen- Washington or elsewhere in the USA. insula, and southward to Fort Canby at the mouth After more than l0 years since the last reports of the Columbia River. The traps were placed of this species, we decided to search for Oc. togoi around natural or man-made rock formations and along the coast of Washington State to further de- were hidden from human view. All traps were with- fine its distribution and abundance and to determine in 50 m of the high-tide line and were checked on a monthly basis (i.e., passive surveillance). As part of the monthly surveillance, potential r U.S. Army Center for Health Promotion and Preven- mosquito habitats that were within tive Medicine-Wesr, Artn: MCHB-AW-ES, Box 339500, 100 m of the MS ll5, 5th & Blaine (Building 9030), Fort Lewis, WA high-tide line were explored for the presence of 98433. mosquito larvae (i.e., active surveillance). In May 'U.S. Navy Disease Vector Ecology and Control Cen- 2OO3, a boat was chartered (Marty Mead, North ter, 2850 Thresher Avenue, Silverdale. WA 98315. Shores Charter, Orcas Island, Washington) for a 2-

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-*.= 3r;Fp;sa;a:?;+i't4t.l h,. = I lFl?4-;aqal S.EE 9 H } t.lg-q,';l;lll-t*:. t F;* s{ si;=-3i:aij*i>e hEl!oE- i.g E; E.l E;P#*g? EE;?e;€i EEFJ>5 CId5EEfErS56"E#;9- ! ts,;.i^ - 108 JounNRr-or rHr AvgnrclN Mosqurro CoNrnol Assocre.uoN Vor-.20, No. 2 copepods (Albert et al. 2001) were observed in as_ of sand, gravel, large pebbles and smooth stones, sociation with Oc. togoi dving this study. Chiron_ or rock formations from the euaternary period. omids were found to be present in every rock hole Rock holes generally are not associated with these containing Oc. togoi. Morley and Ring (1972) con- formations, and little suitable habitat is available ducted an extensive study of intertidal Chironomi_ for breeding by Oc. togoi. Hence, we propose that dae. but did not Iist this association. the lack of suitable habitat outside of the northern In addition to associated species, we observed Puget Sound prevents further expansion of Oc. to- that when larvae and pupae of Oc. togoi were dis- gol in Washington. In the course of our study we turbed they would routinely swim to the bottom of found multiple rock holes at Ruby Beach and Fort the rock hole and remain motionless for an extend_ Canby. Although these sites offered the greatest po- ed period of time, unlike their common associare, tential for finding Oc. togoi in mid- to southern Cs. incidens, which resurfaced rather quickly. Thus, Washington, all active and passive surveillance re- disturbed rock holes that contain only Oc. togoi sults were negative. may appear to be negative for presence of the spe- Populations of adult Oc. togoi are dependent cies, and if not carefully sampled, may be counted upon the number and breeding potential of each as negative by a casual observer. In rock holes with rock hole, and based upon our collections and ob- clear water and small populations of Oc. togoi, we servations, we estimate that the populations of adult ensured collection by lying next to the rock hole Oc. togoi range from near zero (sites with 1 or 2 for close-up viewing and collected larvae from the small rock holes) to perhaps as high as 1,000 (sites bottom with a pipette. This characteristic behavior with several large or deep rock holes) during the of Oc. togoi also was observed in the laboratory primary breeding season. For the sake of compar- and provided an additional means of separating lar- ison, the senior author had the opportunity to visit vae of Oc. togoi from those of Cs. incidens. Lighthouse Park in Vancouver, British Columbia, While collecting in the San Juan Islands, Oc. to- with Peter Belton in November 2002. This locality goi appeared to be more prevalent and hence sig- contained a greater number of rock holes that were nificantly easier to find in certain rock formations noticeably larger and deeper than those observed in than in others. By using geological maps acquired Washington, which thereby represented a superior from the Washington Division of Geology and breeding potential for this species. Earth Resources, Olympia, WA, we discovered that Regarding bloodfeeding, Oc. togoi is known to the rock formations found in the San Juan Islands feed on humans in Asia (Tanaka et al. 1979). How- are geologically unique, and are not found else- eveq only 5 of the 15 sites that we identified were where along the Washington coast. The majority of near homes or areas routinely used by humans. This the breeding sites of Oc. togoi were located in ma- suggests that humans are not the primary source of rine sedimentary rock (or variations thereof) de- blood meals for this species. We observed several rived from the Cretaceous, Cretaceous/Jurassic, Ju- species of birds that frequented or nested near hab- rassic, the Permian/Devonian, and pre-Devonian itat of Oc. togoi, and mammals such as deer, rac- periods (Table 1). These rocks occur at least in part coons. rabbits. and seals also were seen in these on the following islands: San Juan, Spieden, Shaw, same areas. A variety of rodents inhabit these areas Brown, southern Orcas, the southern part and and, along with other mammals and birds, provide northern point of Lummi, northern Cypress, south- blood-meal opportunities for female Oc. togoi. Fur- eastern Sinclair, Vendovi, southwestern Fidalgo, ther research is needed to determine the bloodfeed- northern Decatur, James, Blakely, Burrows, Allan, ing ecology of Oc. togoi in North America. Center, Yellow, Oneil, and northern Whidbey. Currently, Oc. togoi is not known to transmit any Rocks of this type also may occur on smaller is- diseases in North America. If it eventually proves lands near, or in between, these locations. to be a vector of WN and this relationship leads to Secondary breeding strata appear to be in Cre- unacceptable ecological or economic damage, then taceous nearshore and Eocene continental sedimen- the information in this paper can be used during tary rock. These grainy rock formations give the development of control efforts for populations of appearance of sandstone, and are predominant on Oc. togoi. The logistics of finding and accessing Stuart, Johns, Skipjack, Patos, Sucia, Matia, Clark, sites for populations of Oc. togoi will be the most and portions of Waldron islands. Small amounts of difficult aspects of their control. The suggestion is similar rock can be found on Indian, Marrowstone, made here that larval control efforts would be more and southern Bainbridge islands, and the point effective than adult control. State and federal offi- across from southern Bainbridge Island. Erosion cials also would have to determine a control strat- has eliminated many of the potential rock holes in egy for this species, which could include either these strata, but a few deep holes still exist and are temporarily reducing the populations through the utilized by Oc. togoi. The area south of Bellingham, use of biological or chemical controls, or perma- WA, and along Chuckanut Mountain contains this nently reducing the populations through the de- rock and offers the highest potential for finding Oc. struction of rock holes conducive to oviposition by togoi on the mainland. this species. Other portionsof the Washingtoncoast consist To aid the efforts of future studies, the following JUNB 2004 Oc. rocot IN WASHINcToN 109 sites had negative results for active and passive sur- tle, John Wright, Roy Vogtsberge! Pat Pringle, and veillance or active surveillance alone. Sites with Sonya Schleich for their assistance with various passive surveillance (i.e., use of ovitraps) are portions of this study. We also thank Marty Mead marked (P). Sites that had negative results for Oc. and Beth Corbin for their exceptional assistance togoi include CLALLAM COUNTY: Sequim (P), during the island-hopping portion of this study. Port Angles (P), La Push (P), Salt Creek Recreation Neah Bay; GRAYS HAR- Area, Shipwreck Point, R"EFERENCES CITED BOR COUNTY: Hwy 105 at Chapin Creek (P), Hwy 105 at John's River (P), Westport jetties (P); Albert AYK, Borkent CJ, Duquette SL, Voordouw MJ, ISLAND COUNTY: Joseph Whidbey State Park Anholt BR. 2001. Effects of an introduced mosquito on juvenile (Copepoda: Harpacti- (P), South Whidbey Island State Park (P); JEFFER- Tigriopus californicus coidea) in supratidal pools. Arch Hydrobiol 152:2O3' SON COUNTY: Ruby Beach (P), Triton Cove ztJ. Tidelands (P), Port Townsend (P), Belton P 1980. The first record of Aedes togoi (Theo.) in East Beach State Park, , the United States-aboriginal or ferry passenger? Mosq County Park, Old ; KING News 4O:624-626. COUNTY: Dash Point St. Park; KITSAP COUN- Belton P, Belton OC. 799O. Aedes togoi comes aboard. J TY: East Bremerton (P), Silverdale (P), Seabeck Am Mosq Control Assoc 6'.328-329. (P), Tracyton (P), Kitsap Memorial State Park, Sals- Galka BE, Brust RA. 1987. The effect of temperature and bury Point County Park, Point No Point County photoperiod on the induction of larval diapause in the Park, Manchester State Park; MASON COUNTY mosquito Aedes togoi (Theobald) (Diptera: Culicidae). (P), Shelton Public Fishing Ac- Can J Zool 65:2262-2265. Hossack K, Costello RA. 1979. Predation by Anisogam- cess (P), Jerrel Cove State Park (P), Allyn City marus confervicolas (Amphipoda: Gammaridae) on Ae- lO5 at North Cove Park; PACIFIC COUNTY: Hwy des togoi (Diptera: Culicidae). J Entomol Soc B C 76: Pioneer Cemetery (P), 4 miles east of Tokeland on 20-2r. 1/zmlle Hwy 105, south of South Bend on Hwy l0l, LaCasse WJ, Yamaguti S. 1948. Mosquito fauna of Japan Hwy 101 and Niawiakum River (P), boat ramp at cnd Korea APO 343: Office of the Surgeon, Head- Willapa Wildlife Refuge (P), Beards Hollow Park, quarters 8th U.S. Army. Fort Canby State Park (4 areas checked, 2 ovitrap McGinnis KM, Brust RA. 1983. Effect of different sea sites) (P); PIERCE COUNTY: Point Defiance Park, salt concentrations and temperatures of larval devel- Solo Point (P), Steilacoom's Sunnyside Beach (P), opment of Aedes togoi (Diptera:. Culicidae) from British Entomol l2:7 4O6-1471. Chambers Mill Monument on Chambers Creek Columbia. Environ Morley RL, Ring RA. 1972. The inter-tidal Chironomidae Road (P); SKAGIT COUNTY: Bayview State Park (Diptera) of British Columbia. II. Life history and pop- (P), (P), Bowman Road Boat Launch Chuckanut ulation dynamics. Can Entomol 1O4:1O99-1121. (on (P), Drive at Heritage Marker cliff) SE Samish Shestakov VI. 1961. Contribution to the biology of the (P); Island (P), Skagit Wildlife Area-Samish Unit mosquito Aedes togoi. Zool Zh 4O:284-285. [Tiansla- THURSTON COUNTY: , Nis- tion.l qually Head boat ramp (P); WHATCOM COUN- Sollers-Riedel H. 1911. 1970 world studies on mosquitoes TY: Drayton Harbor Road (2 sites) (P), both sides and diseases carried by them. Proc N J Mosq Exterm of peninsula at Semiahmoo Park (P), Birch Bay Assoc Suppl 58:1-52. State Park (P), (P), ferry land- Sota I Ning W, Zhi-Jie H. 1995. Autogeny of Aedes togoi ing at Lummi Island, and the northern point on (Diptera: Culicidae) from Hainan, southern China. Jpn Lummi Island. Sites with negative results in San J Sonir Zool 46:173-175. Tanaka K, Mizusawa K, Saugstad ES. 1979. A revision Juan County from May 2OO3 are not listed, because of the adult and larval mosquitoes of Japan (including of the difficulty of finding Oc. togoi in what we the Ryukyu Archipelago and the Ogasawara islands) described as secondary breeding strata. Although and Korea (Diptera: Culicidae). Contrib Am Entomol we did not find Oc. togoi in our sampling of some Inst (Ann Arbor) 16:1-987. islands with these strata, this does not preclude their Trimble RM. 1984. Aedes togoi (Diptera: Culicidae) dis- existence and future surveys may find small pop- persal: assessment using artificial container habitats and ulations on those islands. miniature light traps. J Med Entomol 2l:l2o-121 . Tiimble RM, Wellington WG. 1978. Effects of salinity on (Diptera: ACKNOWLEDGMENTS site selection by ovipositing Aedes togoi Cu- licidae). Can J Zool 57:593-596. We thank Otha Johnson. Charles Morris. Patti Trimble RM, Wellington WG. 1979. Colonization of Simon, Martha Sames,William SamesV, Tom Lit- North American Aedes togoi. Mosq News 39:-18-2O.