*Filming Global News story, BWP Consulting Inc.

Transcription

1 Final Report of the Regional District of Central Okanagan Nuisance Mosquito Control and West Nile Virus Preventionn Program, 03 *Filming Global News story, 03 Report prepared December, 03 By Burke Phippen, R.P.Bio & Cheryl Phippen, RN,, BSc

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3 Regional District of Central Okanagan Mosquito Control Program, 03 Table of Contents List of Tables... v List of Figures... vi Executive Summary....0 Introduction Nuisance Program West Nile Virus Prevention Program What is West Nile Virus, and Why is it a Concern? West Nile Virus Life Cycle Surveillance in British Columbia Environmenta al Factors Snow Pack Temperature and Precipitation Flow levels Larval Mosquito Surveillance and Treatment Larval Surveillance Larviciding Activities Surface water monitoring and larviciding Catch basin larviciding Tire Collection Program Public Education Radio and Internet Ads Public Outreach Adult Mosquito Surveillance Method of Adult Surveillance Results of Adult Mosquito Surveillance Adult mosquito trapping in Winfield Adult mosquito trapping in Glenmore Adult mosquito trapping near Mission Creek Adult mosquito trapping in Oyama Summary of West Nile Virus Vector Competencyy for BC Mosquito Species Biology of Major Mosquito Species Collected in the RDCO in Aedes and Ochlerotatus Species Aedes cinereus Aedes vexans Ochlerotatus campestris Ochlerotatus canadensis Ochlerotatus communis Ochlerotatus dorsalis Ochlerotatus excrucians Ochlerotatus fitchii Ochlerotatus increpitus Ochlerotatus intrudens Ochlerotatus spencerii (both variants) Ochlerotatus sticticus Page iii

4 Regional District of Central Okanagan Mosquito Control Program, Anopheles Species Anopheles earlei Anopheles freeborni Anopheles punctipennis Coquillettidia Species Coquillettidia perturbans Culex species Culex pipiens Culex tarsalis Culiseta Species Culiseta incidens Culiseta inornata Culiseta minnesotae Culiseta morsitans Recommenda ations References Appendix I. Summary of Larviciding Activities in RDCO in 03 (total amount applied at each site, many of thesee are the result of multiple applications) Page iv

5 Regional District of Central Okanagan Mosquito Control Program, 03 LIST OF TABLES Table. Summary of maximum instantaneous discharge for Mission Creek near East Kelowna between 997 and Table. Summary of surface water larviciding conducted in participating areas of the RDCO in 03, by area Table 3. Summary of tires collected for recycling at the drop-offf events in Table 4. Summary of educational events attended byy staff in the RDCO in Table 5. Numbers of adult mosquitoes captured eachh week in a CDC black-light trap in Winfield Table 6. Numbers of adult mosquitoes captured eachh week in a CDC black-light trap at the landfill in Glenmore Table 7. Numbers of adult mosquitoes captured eachh week in a CDC black-light trap on Gordon Drive in Mission Table 8. Numbers of adult mosquitoes captured eachh week in a CDC black-light trap in Oyama Table 9. Mosquito species in British Columbia identified as potential human West Nile Virus Vectors (Belton, 007) Page v

6 Regional District of Central Okanagan Mosquito Control Program, 03 LIST OF FIGURES Figure. Base 4.3 C degree-day map for BC, 03 (from BCCDC, 03)... 8 Figure. Snow pack at Mission Creek (Ministry of FLNRO Site F05P) in 03, compared with recent years and historical max, min and average (969-03).... Figure 3. Minimum and maximum daily temperatures ( C) measured at Environment Canada weather station Kelowna (3939).... Figure 4. Daily precipitation measured at Environment Canada weather station Kelowna (3939)... 3 Figure 5. Average daily discharge for 03 measured on Mission Creek (WSC Hydrometric Station #08NM6) near East Kelowna, BC, compared with flows from previous high-water years Figure 6. VectoLex WSP, 0g water soluble pouch for larval mosquito control in catch basin Figure 7. Altosid Pellets applied at 7 grams per catchh basin for control of mosquito larvae Figure 8. West Nile Virus Risk Reduction Tire Collection Event at Okanagann College, October 9th, Figure 9. Booth and public outreach at the Kelowna Block Party,, August 0 th, Figure 0. CDC mosquito black-light trap Page vi

7 Regional District of Central Okanagan Mosquito Control Program, 03 EXECUTIVE SUMMARY A nuisance mosquitoo control and West Nilee Virus Mitigation program was conducted within the boundaries of the City of Kelowna, District of Lake Country, a small area in West Kelowna and in the East and West Electoral Areas of the Regional District of Central Okanagann (RDCO). Activities included public education, mosquito surveillance, mosquito control, and habitat modification (tire collections). was contractedd to conductt all activities under this program. Approximately 9 potential larval development sites have been identified within the boundaries of the mosquito control program, and all were monitored for the presence of mosquito larvae in 03. Environmental conditions (including higher than average snow-pack, higher than average temperatures in early May, and higher than average precipitation throughoutt the spring) ) resulted in some of the highest water levels in Mission Creek on record. A total of kg of Vectobac 00G (Bacillus thuringiensiss var israelensis) was applied by hand and backpack blower to 7.0 ha of standing water. In addition,, kg of VectoLex WSP (Bacillus sphaericus) and kg of Altosid pellets (methoprene) were used to treat 8,369 catch basins within the participating areas (8,64 catch basins in late June and 0,05 catch basins in August). Public education expenditures included thee purchase of radio, television and internet advertising, as well, the distribution of various media releases, media interviews and television news stories Informational booths were held at eight events throughout the summer in the participating g communities. Four adult mosquitoo trapping sites were selected within the mosquito control area (in Winfield, Glenmore, Mission and Oyama). The traps operated for between ten weeks during which time the contents of the traps were identified to determine the mosquito species present at the trapping site. A total of 4,858 mosquitoes were captured (with the highest numbers captured in Winfield), representing species. The two primary vectors of WNV, Culex pipiens and Culex tarsalis, weree found in low to moderatee numbers at all of the sites except Glenmore, where Culex tarsalis Page

8 Regional District of Central Okanagan Mosquito Control Program, 03 was found in high numbers. The most prevalent nuisance species were Aedes vexans and Coquillettidi ia perturbans. In order to reduce larval development habitat for WNV vector mosquitoes, a used tire collection program was conducted in October. Four drop-off events were scheduled throughout the RDCO on October 9 th and 0 th. Over this two-day period, a total of,08 tires were collected for recycling. Page

9 Regional District of Central Okanagan Mosquito Control Program, INTRODUCTION The Regional Districtt of Central Okanagan (RDCO) has operated a nuisance mosquito control program for a number of years, andd since 004, RDCO has applied for and received grant funding for a West Nile Virus (WNV) prevention program. Historically, work on both of these programs has been conductedd in-house, with RDCO staff and summer students responsible for program delivery. However, in 0 our company, () was contracted to conduct the entire mosquito control and WNV preventionn program. In 0, funding was no longer made available through the provincial WNV Mitigation program. However, the City of Kelowna,, the Districtt of Lake Country, a smalll portion of West Kelowna and the East and West Electoral Areas of the RDCO opted to continue both the nuisance mosquito controll program and the West Nile Virus Mitigation program by expanding the existing mosquito control budget. The program continued unchanged in 03, and this report is a summary of the work conducted this year... NUISANCE PROGRAM Approximately 9surface water sites that aree capable of producing mosquito larvae have been identified within the 03 mosquitoo control boundary. Each year, stafff are open to searching for or adding new sites as new habitat is discovered or reported by landowners requesting treatment. Sites are visited beginning in late-april, and are monitored for the presence of mosquito larvae. When larvae are found, crews treat the sites with a larvicide containing protein crystals produced by the bacterium, Bacillus thuringiensis var israelensis (Bti). This product (generally marketed under the trade names Aquabac 00G (PCP #6863, a.i..8%) or Vectobac 00G (PCP #858, a.i..8% %) is toxic to aquatic members of the Order Diptera, of whichh mosquitoess are a member. It is virtually non-toxic to other insect Orders, as well as fish, reptiles, amphibians, birds, mammals, and other higher formss of life. Further, when used at target concentrations (typically 3-0 kg/ha), it has limited toxicity to other aquatic Dipteran species such as chironomids. Most of the typical nuisance mosquitoes belong to the genera Aedes and Ochlerotatus. These mosquitoes usually produce a single generation of offspring. Page 3

10 Regional District of Central Okanagan Mosquito Control Program, 03 Female nuisance mosquitoes typically take only one blood meal and lay only one brood of eggs, usually on moist ground that is occasionally flooded. These nuisance mosquitoes (also referred to as floodwater mosquitoes), typicallyy hatch in high numbers when water levels rise in the spring as a result of snowmelt or rising rivers and creeks. When uncontrolled, these mosquitoes can emerge as adults in large swarms that will live for to 6 weeks depending on the species and the weather. These species are usually at their peak in June or early July. This year, the highest numbers of concern calls came from the Mission Creek area, Hall Road area, Lake Country near Lodge Road, and Quail Ridge. Senior staff, Cheryl Phippen, Burke Phippen & Ron Lampreau, visited each of these areas repeatedly this season to assist the local technicians to determinee the sources of the nuisance outbreaks. In addition, a helicopter was hired for an aerial reconnaissance of the Mission, Glenmore and Lake Country areas. Large potential habitats weree explored in the valley next to Gallaghers Golf Course, and near Glenmore Landfill and will be visited earlier in the season this year to search for larvae. In the Quaill Ridge area, it appeared that the habitat had dried up by the time that we visited. We sent a letter to the Quail Ridge strata association asking for help to located standing water near the subdivision and had minimal response... WEST NILE VIRUS PREVENTION PROGRAM In addition to the nuisance program describedd above, RDCO has conducted a WNV Risk Reduction Program for the past nine years. Mosquitoes capable of transmitting the virus differ from typical nuisance species in thatt they are multi- her life and generational, whereby a female mosquitoo will take multiple blood meals in lay multiple broods of eggs on the surface of permanent stagnantt water. In contrast, potential WNV vector species tend to be found in lower concentrations that grow exponentially over the course of the summer as each subsequent generation joins the preceding generation and lays ever-increasing numbers of batches of eggs. These species populations tend to peak in between late-july and mid-september. In addition, because it is impossible to completely eradicate these mosquitoes (the best we can hope for is to keep their numbers below critical levels), educating the public to protect themselves from these species is also important. Therefore, in addition to the Page 4

11 Regional District of Central Okanagan Mosquito Control Program, 03 larviciding component of the WNV Risk Reduction Program, there is an important education component. Finally, a mandate of Integrated Pest Management is to use non-pesticide control whenever possible. To this end, we completed a habitat modification program aimed at reducing the numbers of old tires (which hold standing water and can be ideal mosquito larval habitats) in landowners yards throughout the participating areas (City of Kelowna, District of Lake Country, and the East and West Electoral Areas) )..3. WHAT IS WEST NILE VIRUS, AND WHY ISS IT A CONCERN? West Nile Virus (WNV) is a relatively new disease in North America. It was first detected in New York City in the summer of 999, after the deaths of countless American Crows (Corvus brachyrhynchos). That summer, 6 human casess of WNV were identified in New York, resulting in seven human deaths. At that time, it was unknownn if the outbreak would be an isolated event, and there were questions surrounding the ability of the virus to survive North America s winters. The following spring, these questions were answered as the virus reappeared and rapidly started its migration across the continent. For the next two years, viral activity was confined primarily to the east coast of the U.S. and Canada, but in 00 it advanced quickly across the continentt and by 003 there weree large outbreaks in the Canadian prairies. By 006, WNV was detected in every contiguous U.S. state and in most of the provinces off Canada (except British Columbia (BC) and some of the Maritime Provinces). In August of 009, the first human, non-travel-related, cases of WNV were found in the Okanagan, signaling the arrival of the disease in BC. By October of 009, two locally-acquired human casess were reported in BC, as well as two horses and ten mosquito pools. In 00, one person in the central Okanagan tested positive for WNV, and five birds from the central Okanagann tested positive for the virus. Theree was one equine case of WNV confirmed in the Central Okanagan in 0. In 0, no cases of WNV in humans, birds, mosquitoes or horses were identified. In 03, theree was one confirmed case each of humans, birds, horses and mosquito pools being infected with WNV as of early December, all in the Okanagan. Across Canada WNV infections are down somewhat over last year, with 08 casess reported as of early December 03 (with no deaths), compared with 40 human cases in Page 5

12 Regional District of Central Okanagan Mosquito Control Program, Similarly, in the US,,38 cases were reported as of December 3 rd of this year (including 05 deaths) (CDC, 03), compared with 3,969 cases (and 63 deaths) reported to the CDC by mid-october WEST NILE VIRUS LIFE CYCLE WNV is primarily a disease of birds, especiallyy those of the Corvid Family (crows, ravens, jays, and magpies). It is transmitted from host to host through the bite of particular speciess of mosquitoes. While a number of mosquito species are considered potential vectors, as you will read later in Section 7.00, it is widely accepted that the two primary species for concern in Western Canada are Culex tarsalis and Culex pipiens. Thesee species play different roles in the transmission n of the virus, but both should be considered equally important. When a bird is bitten by an infected mosquito, the mosquitoo injects the virus into the bird. The immune systems of some bird species are able to fight the virus and do not allow the virus to replicate significantly. Members of the Corvid family, however, are especially susceptible to the virus: inside of these birds, the viruss replicates rapidly and is soon present in high concentrations in the blood. When other mosquitoes bite the infected bird, they contract the virus and become infected themselves. Approximately 9- days later, the newly infected mosquitoes are ablee to transmit the virus when they next bite. In British Columbia, as in most of western Canada and the United States, the species of mosquito known as Culex pipiens is responsible for amplifying the virus in the bird population. This species of mosquito feeds almost exclusively on birds, and will take numerous blood meals in a summer, so it has a number of opportunities and thus an increased probability of biting an infected bird and subsequently transmitting the virus to a new host. Each time a female feeds, she then develops a brood of eggs and lays them on stagnant water. With each successive generation, the numberr of individual mosquitoes grows exponentially, simultaneously increasing the chance of a Culex pipiens feeding on an infected bird and communicating the virus. Populations of this insect peak in mid- to late- August, as do the number of cases of WNV in both birds and humans. Culex pipiens are common in urban settings and will readily breed in common water- Page 6

13 Regional District of Central Okanagan Mosquito Control Program, 03 holding containers such as bird-baths, old tires, eavess troughs, wheelbarrows, etc. This species can also breed in exceptionally large numbers in urban catch basins. Once the virus has increased, or amplified, in the bird populations, the risk of spill- over into other hosts increases. A second species of mosquito, Culex tarsalis, is most often implicated in this bridging of the virus from bird populations to mammals. This species of mosquito also has multiple generations each summer and takes numerous blood meals. Some recent Canadian studies suggest that the number of generations that can be produced in a summer is related to the number of degree-days above 4.3 C. The BC Center for Disease Control has produced a degree-day map of BC and has found that many areas of the Okanagan, Thompson-Nicola and Fraser valleys including the RDCO fall in an annual degree-day range of degree-days (Figure ) ). This translates into a potential for 5-7 generations (or more) of Culex tarsalis per summer. In the early summer, Culex tarsalis plays a significant role alongside Culex pipiens in the amplification of the virus, and later in the summer becomes a significant vector of WNV to humans. What is different about this species is its willingnesss to take blood meals from bird hosts as well as mammal hosts, especially later in the summer. Therefore, if an individual of this species takes a meal from an infected bird, it may during a subsequent feeding transmit the virus to a human, horse, or other non-aviann host. In humans, the virus rarely causess serious illness; however, in approximately 0% of infections, humans can experience flu-likon of the brain and/or spinal cord (a condition called meningioencephalitis), whichh can occasionally resultt in symptoms. In less than % of human cases, WNV can cause inflammatio death. Page 7

14 Regional District of Central Okanagan Mosquito Control Program, 03 Figure. Base 4.3 C degree-day map for BC, 03 (from BCCDC, 03) Page 8

15 Regional District of Central Okanagan Mosquito Control Program, SURVEILLANCE IN BRITISH COLUMBIA The British Columbia Centre for Disease Control (BCCDC) and healthh authorities have been anticipating cases of WNV in British Columbia since the summer of 003. In that year, the province began collecting and testing corvids (crows, jays, ravens, and magpies) for the presence of WNV. They also begann using CDCC light traps and gravid traps to attract and collect mosquitoes which were then ground up and tested for the presence of the virus. In the last ten years, 6,640 corvids have been collected and tested, and,999,444 mosquitoes were trapped. All of the Culex femalee mosquitoess were separated and tested as well as many batches of females from other genera (BCCDC, 03). In late August 009, the first human case of locally-acquired (non-travel-related) WNV was discovered, along with a number of mosquito pools also found to contain the virus. In 00, no mosquito pools tested positive forr the virus, but there were five positive birds and one confirmed human case of WNV in BC. In 0, in an effort to stay ahead of the virus, a number of traps were deployed by the Interior Health Authority in the North Okanagan, including the City of Salmon Arm. However, none of the mosquitoes collected in these traps ested positivee for the virus in 0. As well, no humans, birds or horses tested positive for the virus although it should be noted that mosquito surveillance activities were significantly reduced and corvid collections were not supported in any areas of the IHA. In 03, there was one case each of a human, horse, bird, and mosquitoo pool infected with WNV, all of which occurred in the Okanagan..0 ENVIRONMENTAL FACTORS F Mosquitoes are similar to most other flies in that they pass through seven stages during their life cycle: egg, four larval instars, pupa, and adult. Their eggs are laid in water or on moist soil, and the larvae require stagnant, relatively low-oxygen standing water to mature and pupate. As adult mosquitoes aree generally hardy and able to survive in a wide range of environments, mosquito populations are generally restricted only on the basis of suitable larval habitat. Unlike other areas of the southern interior of BC, the geography of the RDCO is not dominatedd by a river valley that iss subject to flooding, but Page 9

16 Regional District of Central Okanagan Mosquito Control Program, 03 ratherr the large lakes of the Okanagan drainage. Therefore, many of the larval development sites are permanent and semi-permanent ponds thatt produce both nuisance species (when melting snow raises water levels in thee spring, causing the nuisance eggs to hatch) and WNV vector species capable of laying their eggs on the surface of the water. Low-lying areas along Mission Creek are onee significant departure from this norm, as relatively large areas are floodedd in high water years, producing significant larval development habitat. Snow pack, coupled withh temperature and precipitation, are the predominant factors affecting both snow-melt pools and ratess and heights of creek floods... SNOW P PACK Snow pack describes the volume of snow in a given area based on its water equivalent, or weight, rather than depth. This provides an objective means of measuring the absolute volume of snow that has accumulated att a site, since measuring depth alone does not take into consideration variations in snow density. Water equivalents are generally measured using snow pillows which are large plastic bags containing antifreeze. A pressure sensor records the weight of snow on top of the snow pillow, and converts this value to a volume in millimeters of water. The B.C. Ministry of Environment operates a number of these snow pillows throughout the province to determine the snow-pack in key watersheds. One of these stations is located at the top of the Mission Creek watershed at,794m elevation (Station F05P). Snow pack at Mission Creek began the year at approximately 0% of average levels, gradually increasing to approximately 30% of average by early May (Figure ). Snowpack continued to increase until early May, andd while lower than that seen in 0, was still somewhat higher than those seen in 0, and considerably higher than average. Page 0

17 Regional District of Central Okanagan Mosquito Control Program, 03 Figure. Snow pack at Mission Creek (Ministry of FLNRO Site F05P) in 03, compared with recent years and historical max, min and average (969-03)... TEMPERATURE AND PRECIPITATION While the overall volume of snow (described by snow pack) dictates, to a large extent, the total discharge carried throughh the watershed, the timing of the melt (and therefore the timing and magnitude of peaks in river flow) are strongly influenced by air temperature and precipitation n. Warmer than averagee temperatures or large amounts of precipitation can result in rapid snow melt, and consequently, rapid rises in river levels. As well, rain falling on snow is not absorbed into thee ground, which acts as a buffer, but typically runs over the surface of the snow and is discharged into tributaries, and also speeds snow melt. This can result in extremely rapidd rises in water level and significant flooding. In 03, high temperatures in early May (Figure 3) resulted in a rapid rise in Page

18 Regional District of Central Okanagan Mosquito Control Program, 03 water levels in Mission Creek and above average rainfall throughout the spring (Figure 4), resulted in a number of rapid rises and falls in thee hydrographh (Figure 5). These rain events in June were in large part responsible for the highest maximum instantaneous discharge in Mission Creek in the last 7 years (Table ), considerably higher than the maximum instantaneous peak in 0. The maximumm average daily discharge (compared with the instantaneous peak, which is measured everyy five minutes) was higher in 03 than any year since 997 (Figure 5. Average daily discharge for 03 measured on Mission Creek (WSC Hydrometric Station #08NM6) near East Kelowna, BC, compared with flows from previous high-water years.). Figure 3. Minimum and maximum daily temperatures ( C) measured at Environment Canada weather station Kelowna (3939). Page

19 Regional District of Central Okanagan Mosquito Control Program, 03 Figure 4. Daily precipitation measured at Environment Canada weather station Kelowna (3939)..3. FLOW LEVELS Flow levels in Mission Creek climbed rapidlyy in early May and fluctuated according to temperature and precipitation until rising to the annual peak on June 0, 03 (Figure 5). Table shows the maximum instantaneous discharge for Mission Creek between 997 and 03. The maximum instantaneous peak flow in 03 was higher than that measured in the past 7 years, but daily average flows remained slightly below the 997 levels (Figure 5). This is due to the rapid rise and fall of water levels in 03 while the maximum instantaneous discharge was higher in 03, the fact that water levels rose and fell quickly resulted in a lower overall daily average on the day when the maximum flow occurred, since water levels remained at a relatively high level for a longer period in 997. Page 3

20 Regional District of Central Okanagan Mosquito Control Program, 03 Figure 5. Average daily discharge for 03 measured on Mission Creek (WSC Hydrometric Station #08NM6) near East Kelowna, BC, compared with flows from previous high-water years. Page 4

21 Regional District of Central Okanagan Mosquito Control Program, 03 Table. Summary of maximum instantaneous discharge for Mission Creek near East Kelowna between 997 and 03. Year Maximum Instantaneou us Discharge (m 3 /s) Datee when maximum occurred May 3 May 0 Jun 4 Jun 5 Jun 0 May Jun 4 Jun 06 May 6 Jun 5 Jun 05 May 6 May 3 Jun Jun 08 Jun 0 Jun LARVAL MOSQUITO SURVEILLANCE AND TREATMENT 3.. LARVAL SURVEILLANCE Beginning in early May, larval development sites were monitored for the presence of larvae. Under provincial legislation, all water thatt is to be treated for mosquito control must first be sampled to confirm the presence of larvae. A 350 ml mosquito dipper was used to sample water from various locations around potential sites and the number of larvae captured in the dipper were counted and recorded. When larvae were present, treatment were conducted with permission of the appropriate landowner or agency. A summary of all monitoring and treatmentt data is provided in Appendix B. Catch basins throughout the City of Kelowna and Lake Country were monitored using an aquarium net attached to a piecee of doweling. The net was lowered through the catch basin grates and swished in a figure-eight pattern for 0 seconds and then rinsed in a bucket with clean water to check for larvae. Page 5

22 Regional District of Central Okanagan Mosquito Control Program, LARVICIDING ACTIVITIES 3... Surface water monitoring and larviciding The RDCO has a Pest Management Plan (Confirmation Number4-007-/6) ), and all mosquito control activities were conducted under this plan. Vectobac 00G (PCP #858) was the biological larviciding agent that was used to treat surface water sites in the RDCO this summer. This product contains metabolites of the bacteria Bacillus thuringiensis var israelensis. Vectobac 00G is highly specific to mosquito larvae. When applied according to the label, amphibians, fish, bird, mammals and even other insects and invertebrates that ingest the product are unharmed. It is a granular product that is formulated on ground corn cob so it can be easily distributed onto the surface of mosquito larval development habitat byy hand or by helicopter. Vectobac 00G has no residual action and will only kill the larvae that are present in the water at the time of application. A total of kg of Vectobac 00G was applied to 7.0 ha of surface water containing mosquito larvae this yearr (Table ), compared with kg applied in 0 and kg in 0. Water levelss in Mission Creek were very high this year, and frequently peaked and fell, resulting in n significant larval development habitat in the Mission area. The Mission area was where the majority of larviciding activities occurred. Table. Summary of surface water larviciding conducted in participating areas of the RDCO in 03, by area. Area Airport Downtown Gallagher s Glenmore Mission Rutland Winfield/Oyama Total Amount of larvicide (kg) Area treated (ha) Page 6

23 Regional District of Central Okanagan Mosquito Control Program, Catch basin larviciding VectoLex WSP (PCP #8009) and Altosid Pellets (PCP #809) were used to treat catch basinss in the RDCO. VectoLex WSP is formulated in 0g pouches and a single pouch is dropped into each catch basin. Altosid Pellets are black charcoal-looking pellets and they are applied at a rate of 7g per basin which is approximately one teaspoon. Bacillus sphaericus is the active ingredient in VectoLex WSP. The mode of action of the bacteria is similar to Bti in that it produces toxins that attack the gut of mosquito larvae. The benefits of Bacillus sphaericus are also similar too those of Bti in that it is virtually non-toxic to non-target This product works better than Bti when applied to highly organic larval habitats and it has the added benefit of maintaining its effectiveness for up to 8 days and thus organisms while being very effective and specific to mosquito larvae. can control multiple generations of larvae with a single application, as is desirable when controlling Culex pipiens in catch basins. Altosid Pellets is the trade name of a mosquitoo larvicide that contains the active ingredient methoprene (4.5% a.i.). Methoprene is a mosquito growth regulator that mimics mosquito juvenile growth hormone. In mosquitoes, juvenile growth hormone production ceases when a mosquito pupates. This allows the mosquito to develop into an adult while inn its pupal stage. When methoprene is present in the water, pupae are unable able to develop into adults and the mosquitoes die in their pupal stage. In 0, catch basins were treated in Lake Country, Kelowna, West Kelowna, and Peachland, while in 0 and 03, only catch basinss in Lake Country and Kelowna (as well as a small portion of West Kelowna that is part of the nuisance program) were treated. Between June nd and June 5 th, 8,64 catch basins in Lake Country, Kelowna and a portion of West Kelowna were treated with VectoLex WSP (3,800 catch basins with 38.0 kg of larvicide) or Altosid (4,364 catch basins with kg of larvicide). Catch basins were treated a second time between August 3 rd and 6 th, when a total of 0,05 catch basins were treated with 0.05 kg of VectoLex WSP. Page 7

24 Regional District of Central Okanagan Mosquito Control Program, 03 Figure 6. VectoLex WSP, 0g water soluble pouchh for larval mosquito control in catch basin. Figure 7. Altosid Pellets applied at 7 grams per catch basin for control of mosquito larvae. Page 8

25 Regional District of Central Okanagan Mosquito Control Program, TIRE C COLLECTION PROGRAM As mentioned in Section 8.4., one of the main WNV vector species, Culex pipiens, typicallyy rears in small containers in urban or semi-urban areas. Part of our educational program is to educate peoplee to remove or replace on a weekly basis standing water on their property, to minimize larval development habitats and reduce overall vector numbers. However, one common site on many people s property thatt is difficult for them to dump out are old tires. Thesee accumulatee water from precipitation or irrigation, and this water is typically filled with organic material,, resulting in a warm and ideal rearing habitat for mosquito larvae. In order to reduce this problem, for the past few years the RDCO has offered a free tire pick-up/drop-off recycling program, whereby tires could be droppedd off at one of a number of events at various locations throughout the RDCO, orr appointments could be scheduled for pick-ups for those individuals unable too attend the drop-off events. Collection service was available to residents of the City of Kelowna, Districtt of Lake Country and the West and East Electoral Areas as these were the areas contributing to the cost of the service. In 03, four drop-off events were scheduled, and no pick-up program was included due to decreased response in 0 compared with 0 (,456 tires were picked up or dropped off in 0, compared with 8,39 tires collected in 0). Bruce Smith arranged the advertising of the tire collection program this fall. Advertisements of the event dates and call numbers to schedule a pick up were placed in the Kelowna Courier, Kelowna Capital News, and the New View in Lake Country. Advertising was also purchased on Castanet. In addition, Bruce Smith issued a media release to promote the program. The drop-off Elementary School in Kelowna and October 0 th at Casorso Elementary School in Kelowna and George Elliot Middle Schooll in Lake Country. A summary of the numbers of tires collected at the four drop-off events is given in Table 3. Response to the drop-off program was considerably higher this year compared with 0, and similar to events were October 9 th at Okanagan College (Figure 8) and North Glenmore the response levels seen in 0. Residents made a number of very positive comments regarding the program while dropping off tires. Page 9

26 Regional District of Central Okanagan Mosquito Control Program, 03 Figure 8. West Nile Virus Risk Reduction Tire Collection Event at Okanagan College, October 9th, 03. Page 0

27 Regional District of Central Okanagan Mosquito Control Program, 03 Table 3. Summary of tires collected for recycling at the drop-off events in 03. Location Okanagan College Drop off event Non rimmed Rimmed North Glenmore Drop off event Non rimmed Rimmed Non rimmed tractor trailer tires Rimmed tractor trailer tires Casorso Drop off event Non rimmed Rimmed Lake Country Drop off event Non rimmed Rimmed Non rimmed tractor trailer tires Rimmed tractor trailer tires Total: Numberr of Tiress , PUBLIC EDUCATION As mentioned in Section.. it is not possiblee to eradicate the vector mosquito species responsible for the transmission of WNV. For this reason, it is important that people are made aware of the potential risks, and taught methodss to reduce these risks. WNV vector species populations tend to peak between mid-august and mid-september, to protecting themselves from mosquito bites. We can reduce the risk of individuals contracting the at a time when people have often lowered their guardd with respect virus by reminding them to use simply precautions for avoiding mosquito bites. These include: using insect repellents such as those containing DEET; wearing light-coloured, long sleeved clothing; avoiding outdoor activities during dawn and dusk (when these mosquitoes are most active); ensuring that screens onn windows don t have holes; and reducing larval development habitats around their households. In order to convey this information to the public, we used a number of strategies, including radio, and internet advertisements, staffing informational booths at public events, and developing educational poster boards and brochures. Page

28 Regional District of Central Okanagan Mosquito Control Program, RADIO AND INTERNET ADS In 03, Bruce Smith, Communicat tions and Intergovernmental Affairs Coordinator for RDCO purchased and oversaw the RDCO Mosquito Control advertising campaign. Ads were placed on Castanet.net as well as radio stations AM 50, EZ Rock 0.5, Power 04 and Q 03.. This summer, the RDCO also funded a two month summer Public Service Announcement campaign with more than,800 airings on SHAW Central Okanagan TV and 6 cable Specialty Channels. Advertising wass also purchased on Castanet and in the Capital News and Lake Country Calendar to promote the fall free Tire Collection locations in Kelowna and Lake Country. In addition to the advertising, the Regional District also produced a number of media releases and Public Service Announcements about the program and its various activities and as a result staff were interviewedd by CBC Radio, many local newspapers, and Global television. In alll cases, information wass presented concerning the components of the mosquito control program as well tips for reducing the risk of WNV. 5.. PUBLIC OUTREACH During the summer, our staff members set upp and tended a West Nile Virus Education Booth at eight events (Table 4, Figure 9). Along with the informational banners, live larvae were displayed, and adult mosquitoes were available for viewing. Literature including the brochure developed for RDCO, the Interior Health Authority WNV pamphlet Put the Bite on West Nile Virus, a Health Canada pamphlet, an information sheet concerning DEET, and numerous handouts describing the WNV in horses were made available the booth. To help attract the public, we offered candy and a bug tattoo, stickers and toy bugs for the children. Page

29 Regional District of Central Okanagan Mosquito Control Program, 03 Table 4. Summary of educational events attendedd by staff in the RDCO in 03. Date Event Monday, Jul Canada Day Sun, Jul 4 Fintry Fair Weds, Jul 7 Farmer s Market Friday, Jul 9 Farmer s Market Saturday Jul 0 Canada Parks Day Weds, Aug 7 Farmer s Market Sat, Aug 0 Kelowna Block Party Sun, Sept Kokanee Salmon Festival Location Waterfront Park, Kelowna Fintry Provincial Park Dilworth, Kelowna Swalwell Park, Lake Country Bertram Park, Kelowna Dilworth, Kelowna Downtown Kelowna Mission Crk Regional Park, Kelowna Figure 9. Booth and public outreach at the Kelowna Block Party, August 0 th, ADULT MOSQUITO SURVEILLAS ANCE Adult mosquitoes were trapped in the RDCO to determine which species were present and their relative numbers. Since only a few mosquito species are capable of transmitting WNV, it is important to know which species are present in an area, and the size of their populations when determining a level of f risk for an area. Also, since some Page 3

30 Regional District of Central Okanagan Mosquito Control Program, 03 species can pose a significant nuisance problem, it is important to monitor the populations of nuisance mosquitoes as an assessmentt of the effectiveness of the nuisance mosquito control portion of the project. 6.. METHOD OF ADULT SURVEILLANCE Adult mosquitoes were captured with the use of CDC black-light mosquito traps (Figure 0). The CDC traps are operated with a 6V, Amp hour battery which runs the trap for up to 4 hours. The traps are equipped with a photocell to detect dawn and dusk (when mosquitoes are most active). At dusk, a fluorescent black-light and a small fan were switched on. Mosquitoes are attracted to the light and, when they come near the fan, they are sucked into a collecting jar. In addition to the light, dry ice was placed in a beverage cooler adjacent to the trap. Dry ice sublimates into carbon dioxide, a powerful mosquito attractant that brings mosquitoes near the collecting fan. Four trapping locations were selected within the boundaries of the mosquito control program, in Winfield, Glenmore, Mission andd Oyama. Ten sets of samples weree collected in Winfield and Oyama and nine were collected in Glenmore and Mission. Traps were initially set on June 0 th or June 3 nd and samples collected the following day. Sampling was conducted on a weekly basis between June th and August 30 th. Trap contents were shipped to Kamloops for identificationn to species level (Table 5 to Table 8). Page 4

31 Regional District of Central Okanagan Mosquito Control Program, 03 Figure 0. CDC mosquitoo black-lightt trap. 6.. RESULTS OF ADULT MOSQUITO SURVEILLANCE The following Sections include the results of all adult mosquito surveillance conducted in the RDCO in 03. There were total off 4,858 specimens representing species captured from all six of British Columbia s mosquito genera. The two most important vectors of WNV, Culex pipiens and Culex tarsalis, were both captured all of the sites, and the primary vector (Culex tarsalis) wass most numerous in Glenmore. The primary nuisance species captured were Aedes vexans, Coquillettidia perturbans, and Ochlerotatus increpitus. The trap at Winfield caughtt slightly more mosquitoes than any of the other traps (approximately 3% of all mosquitoes captured). Page 5

32 Regional District of Central Okanagan Mosquito Control Program, Adult mosquito trapping in Winfield The first light-trap was located in Winfield. Over the course of 0 weeks,,59 mosquitoes from 5 species were captured, up considerably from the 46 mosquitoes from ten species captured in 0. The most common species present were the nuisance species Aedes vexans and Coquillettidia perturbans. Both of the primary WNV vector species, Culex tarsalis and Culex pipiens, were present in moderate numbers. Table 5. Numbers of adult mosquitoess captured each week in a CDC black-light trap in Winfield. Species Aedes cinereus Aedes vexans Anopheles earlei Anopheles freeborni Anopheles punctipennis Coquillettidia perturbans Culex pipiens Culex tarsalis Culiseta incidens Culiseta inornata Ochlerotatus canadensis Ochlerotatus communis Ochlerotatus increpitus Ochlerotatus spencerii var idahoensis Ochlerotatus sticticus Mosquito unidentifiable* Ochlerotatus male unidentified** Total Number Captured No of males (out of total above) 3 3 *Specimen too damaged to be identified **Ochlerotatus males can be difficult to identify Jun 4 Jun Jul 05 7 Jull Date (03) Jul Jul Jul Aug Aug 6 Aug Total ,59 38 Page 6

33 Regional District of Central Okanagan Mosquito Control Program, Adult mosquito trapping in Glenmore A second light trap was located at the landfilll site in Glenmore, and operated for nine weeks. Over that time period,,084 mosquitoess from 5 species were captured, up from the 6 mosquitoes captured in 0. The most prevalent species found was the primary WNV vector speciess Culex tarsalis (38 specimens, or 35% of the total number caught), followed by a number of nuisance species. Culex pipiens were also found in low numbers. Table 6. Numbers of adult mosquitoess captured each week in a CDC black-light trap at the landfill in Glenmore. Jun Species 4 Aedes cinereus Aedes vexans Anopheles freeborni Anopheles punctipennis Coquillettidia perturbans Culex pipiens Culex tarsalis Culiseta incidens Culiseta inornata Culiseta morsitans Ochlerotatus campestriss Ochlerotatus canadensis Ochlerotatus dorsalis Ochlerotatus increpitus Ochlerotatus sticticus 3 Mosquito unidentifiable* Ochlerotatus male unidentified** Total Number Captured 3 No of males ( out of total above) 3 8 *Specimen too damaged to be identified **Ochlerotatus males can be difficult to identify Date (03) Jun Jul Jul Jul Jul 9 4 Jul Trap malfunctioned- no sample obtained Aug Aug 6 Aug Total , Page 7

34 Regional District of Central Okanagan Mosquito Control Program, Adult mosquito trapping near Mission Creek The third light trap was located in Mission, along Gordon Drive. Nine sets of samples were collected from this trap. A total of 9600 mosquitoes, representing sixteen species, were captured, down somewhat from the,454 mosquitoes captured in 0. Not surprisingly, the majority of these (78%) were comprised of threee nuisance species: Aedes vexans, Ochlerotatus sticticus, and Ochlerotatus increpitus. All of these species are ferocious nuisance biters, but none are considered to be significant vectors of WNV. The two primary WNV vector species, Culexx tarsalis and Culex pipiens, were both present in relatively low numbers. Table 7. Numbers of adult mosquitoess captured each week in a CDC black-light trap on Gordon Drive in Mission. Jun Species 4 Aedes cinereus Aedes vexans Anopheles freeborni Anopheles punctipennis Coquillettidia perturbans Culex pipiens Culex tarsalis Culiseta inornata Culiseta minnesotae Ochlerotatus communis Ochlerotatus dorsaliss Ochlerotatus excrucians Ochlerotatus fitchii Ochlerotatus increpitus Ochlerotatus intrudens Ochlerotatus sticticus Mosquito unidentifiable* Ochlerotatus male unidentified** Total Number Captured 0 Battery malfunctioned- no sample obtained No of males (out of total above) 4 *Specimen too damaged to be identified **Ochlerotatus males can be difficult to identify Date (03) Jun 3 Jul 05 Jul 0 Jull Jul 9 Jull Aug 07 Aug Aug 30 6 Total Page 8

35 Regional District of Central Okanagan Mosquito Control Program, Adult mosquito trapping in Oyamaa The fourth trap was located in Oyama (Greenhow). Overr the course of the summer,,85 mosquitoes from seventeen different species weree captured, about 50% higher than the 85 specimens captured in 0. Thee two most common species were Coquillettidia perturbans and Aedes vexans, both significant nuisance species. Both of the important WNV species, Culex pipiens and Culexx tarsalis, were found in moderate numbers at this trapping location. Table 8. Numbers of adult mosquitoess captured each week in a CDC black-light trap in Oyama. Date (03) Species Jun Jun Jun Jul Jul Jul Jul Aug Aug Aug Total Aedes cinereus Aedes vexans Anopheles earlei Anopheles freeborni Coquillettidia perturbans Culex pipiens Culex tarsalis Culiseta incidens Culiseta inornata Culiseta minnesotae 8 0 Ochlerotatus canadensis Ochlerotatus communis 5 6 Ochlerotatus dorsaliss 3 Ochlerotatus excrucians 3 Ochlerotatus fitchii Ochlerotatus increpitus Ochlerotatus sticticus Mosquito unidentifiable* Ochlerotatus male unidentified** Total Number Captured No of males (out of total above) ,85 *Specimen too damaged to be identified The following Section (Section 7.0 ) containss an overview of potential WNV vector mosquitoes as predicted by Peter Belton, PhD, Mosquito Expert from Simon Fraser University. Section 8..0 contains short summaries of the biology of the genera and major mosquito species captured in the RDCO this summer. Page 9

36 Regional District of Central Okanagan Mosquito Control Program, SUMMARY OF WEST W NILE VIRUS VECTOR COMPETENCY FOR BC MOSQUITO SPECIES Although it is widely accepted that Culex pipiens and Culex tarsalis are the two primary vectors of WNV in western Canada, Peter Belton (007), a retired professor from Simon Fraser University and an expert in the field of mosquito biology, has assembled a list of potential WNV vectors that are present in British Columbia, and has assigned them vector competency ratings. It is important to understand the factors that must be met for a mosquito to be considered a good WNV vector. First, the mosquito must be willing to bite birds. In a natural setting, WNV can only be contracted from birds, as otherr hosts contain insufficient amounts of the virus to be infectious. Next, the mosquito must have the correct receptors in its gut to accept the virus and transfer it into the mosquito s circulatory system. Later, the mosquito must be ablee to transfer the virus from its circulatory system into its salivary glands so it can inject the virus during its next blood meal. This brings us to the next point: a mosquito must be willing to take more than one blood meal in its life, and must be a long-lived species, since it can take up to two weeks for the virus to be transported to a mosquito s salivary glands and render thatt mosquito infectious. Another factor is the temporal distribution of a species: WNV tends to be at its worst in July and August, so the vector must be present in high numbers during this time of the year. Finally, in order to be a human vector, the mosquito must not only be willing to bite birds, but it must also be willing to bite humans. With all of these factors considered, Culex tarsalis should be identified as the most significant concern as a human vector in Britishh Columbia and Culex pipiens as the most significant vector within bird populations. However, Peter Belton has included British Columbian species in his list, based on a United States Centre for Disease Control list of species that has tested positive for the virus (indicated by a P in Table 9) and a system of ranking discussed in Turell et al. (005). Peter Belton has assigned mosquitoes a relative competency ranking of 0 to (Table 9) ). Species not included in the study by Turell et al, (005), but still given consideration by Peter Belton based on their ability to transmit other viruses, are ranked with a question mark. Page 30