THOMPSON-NICOLA REGIONAL DISTRICT

NUISANCE CONTROL PROGRAM

2011 YEAR-END REPORT

Prepared by:

______Burke Phippen, BSc., RPBio. Project Manager

______Cheryl Phippen, BSc., RN Field Coordinator

NOVEMBER, 2011 BWP CONSULTING INC. 6211 Meadowland C res S, Kamloops, BC V2C 6X3

2011 Thompson-Nicola Regional District Mosquito Control Program

Table of Contents

LIST OF FIGURES ...... IV

LIST OF TABLES ...... V

EXECUTIVE SUMMARY ...... 1

1.0 INTRODUCTION ...... 3

1.1. RESOURCES AVAILABLE FOR MOSQUITO CONTROL PROGRAM ...... 5

2.0 ENVIRONMENTAL FACTORS ...... 5

2.1. SNOW PACK ...... 5

2.1. TEMPERATURE AND PRECIPITATION ...... 7

2.2. FLOW LEVELS ...... 9

3.0 LARVICIDING PROGRAM ...... 10

3.1. HAND APPLICATION OF LARVICIDE ...... 14

3.2. HELICOPTER APPLICATION OF LARVICIDE ...... 14 3.2.1. Snowmelt and Grassland Applications ...... 15 3.2.2. North and South Thompson Floodwater Applications ...... 15

4.0 ADULTICIDING PROGRAM ...... 16

4.1. CALIBRATION OF ULV SPRAYERS ...... 17

4.2. APPLICATION OF ADULTICIDES ...... 18

5.0 LIGHT TRAPS ...... 19

5.1. ANALYSIS OF 2011 LIGHT TRAP CATCHES ...... 20

6.0 BIOLOGY OF MAJOR MOSQUITO SPECIES COLLECTED ...... 28

6.1. AEDINES IN GENERAL ...... 28 6.1.1. Aedes cinereus ...... 28 6.1.2. Aedes vexans ...... 29 6.1.3. dorsalis ...... 29 6.1.4. Ochlerotatus excrucians ...... 30 6.1.5. Ochlerotatus fitchii ...... 30 6.1.6. Ochlerotatus implicatus ...... 30 6.1.7. Ochlerotatus increpitus ...... 31 6.1.8. Ochlerotatus punctor ...... 31 6.1.9. Ochlerotatus sierrensis ...... 31

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6.1.10. Ochlerotatus spencerii (both variants)...... 31 6.1.11. Ochlerotatus sticticus...... 32

6.2. CULEX SPECIES ...... 32 6.2.1. Culex tarsalis ...... 33 6.2.2. Culex pipiens ...... 33

6.3. SPECIES ...... 34 6.3.1. Culiseta alaskaensis ...... 34 6.3.2. Culiseta incidens ...... 34 6.3.3. Culiseta inornata ...... 35 6.3.4. Culiseta minnesotae ...... 35 6.3.5. Culiseta morsitans ...... 36

6.4. SPECIES ...... 36 6.4.1. Anopheles earlei ...... 37 6.4.2. ...... 37 6.4.3. Anopheles punctipennis ...... 37

7.0 MOSQUITO ADVISORY LINE ...... 38

8.0 THE KAMLOOPS SPRING AND FALL HOME AND GARDEN SHOWS & TRAVELLING

ROAD SHOW ...... 39

9.0 WEST NILE VIRUS ACTIVITIES ...... 40

10.0 RECOMMENDATIONS ...... 40

REFERENCES ...... 41

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LIST OF FIGURES

Figure 1. Map outlining electoral boundaries and nuisance Mosquito Control Areas within the Thompson-Nicola Regional District...... 4 Figure 2. Snow pack at Kostal Lake, in the North Thompson watershed ...... 6 Figure 3. Snow pack at Park Mountain, in the South Thompson watershed...... 7 Figure 4. Minimum and maximum daily temperatures (°C) measured at Environment Canada weather station Blue River CS (1160H99)...... 8 Figure 5. Daily precipitation measured at Environment Canada weather station Blue River CS (1160H99)...... 8 Figure 6. Daily flows for 2011 measured on the North Thompson River (WSC Hydrometric Station #08LB064) at McLure Ferry, BC, compared with flows from previous high-water years...... 9 Figure 7. Hydrograph of the North Thompson River at McLure showing dates of 2011 helicopter larviciding applications...... 16

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LIST OF TABLES

Table 1. Summary of maximum instantaneous discharge for the North Thompson River at McLure between 1998 and 2011...... 10 Table 2. Historic amounts of granular larvicide (Bacillus thuringiensis var israelensis) used in the TNRD...... 12 Table 3. Application of Bti Larvicides in Mosquito Area South (Kamloops, Chase, Logan Lake, Areas ‘J’, ‘L’, & part of ‘P’...... 13 Table 4. Application of Bti Larvicides in Mosquito Area North (Area ‘O’ and part of ‘P’)...... 13 Table 5. Application of Bti Larvicides in Electoral Area ‘A’ ...... 14 Table 6. Results of calibration activities for adulticiding equipment...... 18 Table 7. Volumes of Malathion and Resmethrin used in the TNRD since 1989...... 19 Table 8. Mosquito specimens collected in the New Jersey light trap at the Waste Water Treatment Plant in Kamloops, BC...... 22 Table 9. Mosquito specimens collected in the New Jersey light trap in Noble Creek, BC...... 22 Table 10. Mosquito specimens collected in the New Jersey light trap in McLure, BC. ... 23 Table 11. Mosquito specimens collected in the New Jersey light trap in Darfield, BC. .. 23 Table 12. Mosquito specimens collected in the New Jersey light trap in East Blackpool, BC...... 24 Table 13. Mosquito specimens collected in the New Jersey light trap near the Roundtop Road Wildlife Sanctuary in Blackpool, BC...... 24 Table 14. Mosquito specimens collected in the New Jersey light trap in Clearwater, B.C...... 25 Table 15. Number of mosquitoes trapped in each of the New Jersey Light Traps...... 26 Table 16. Historic numbers of mosquitoes trapped per night in Areas ‘J’, ‘L’, ‘O’ and ‘P’, and Area ‘A’. Trapping sites vary over the years, as do overall trapping periods and attractants used...... 27

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EXECUTIVE SUMMARY

Environmental conditions (including an well above-average snowpack, above- average precipitation and cooler than usual temperatures), resulted in a higher than average peak in the North Thompson River that remained above flood levels for considerably longer than usual. Groundwater levels were generally below average, resulting in a less than average number of snow-melt ponds requiring larviciding. Water levels in the South Thompson were near normal.

A total of 12,719.85 kg of larvicide with the active ingredient Bacillus thuringiensis var israelensis (Bti), was applied to 2,286.095 ha of larval habitat as part of the nuisance control program this summer: up considerably from the 5,604.25 kg applied in 2010; the 11,011.8 kg applied in 2009; and the 9,666.7 kg applied in 2008.

Of the total Bti larvicide, 11,400.4 kg of Vectobac 200G (PCP 18158) was applied to 2,153.75 ha surface water (9,516.6 kg was applied to 1,825.53 ha of surface water by helicopter, and 1,883.8 kg was applied to 328.22 ha of surface water by hand and backpack blower application). The remaining 1,319.45 kg of Bti larvicide was Aquabac 200G (PCP 26863) and 1,303.2 kg of this was applied by helicopter to 130.32 ha of surface water and 16.25 kg of this was applied by backpack blower to 2.025 ha of surface water.

In addition to the Bti larvicide, 16 kg of Altosid Pellets (PCP 21809) were applied to 1.6 ha of standing water in the Pritchard area.

No adulticiding was performed in 2011.

Seven light traps were deployed throughout the North Thompson watershed (in Clearwater, Blackpool, East Blackpool, Darfield, McLure, Noble Creek and Kamloops) between early-June and mid-August, each was sampled on a weekly basis to estimate population sizes and determine species distribution. A total of 7,208 mosquitoes representing 22 different mosquito species were trapped and identified during this time. This resulted in an average of 1.7 mosquitoes per night in Area A, and 24.8 mosquitoes per night in the remaining areas. Aedes and Ochlerotatus spp. represented 34% of the catch, Culex spp. 52%, Culiseta spp. 13%, and Anopheles spp. and Coquillettidia perturbans each less than 1% of the total catch.

Approximately 19 telephone calls are recorded in the Thompson-Nicola Regional District (TNRD) Online Database. There were approximately 15 others that are no longer recorded in the database due to a data loss at the TNRD in June. The majority of calls came in the first week of July and these were primarily from the Blackpines area. Most landowners in the area wanted information regarding our larviciding schedule, although we also had two requests for adulticiding. One individual decided that she no longer wanted to be considered for adulticiding after

BWP Consulting Inc Page 1 2011 Thompson-Nicola Regional District Mosquito Control Program she learned that the product used was malathion and the other did not meet the bite count thresholds for adulticiding.

2011 marks the thirteenth year that BWP Consulting Inc. has conducted the mosquito control program in the TNRD, and second year of a five-year contract. It is also the ninth year in a row where no adulticiding was performed.

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1.0 INTRODUCTION

The Thompson-Nicola Regional District (TNRD) began its formal mosquito control program approximately 40 years ago. Initially, the program consisted solely of the aerial application of pesticides such as malathion to control adult populations of mosquitoes. However, with the advent of new products such as biological larvicides, the program shifted its focus to the more environmentally sound practice of controlling mosquito larval populations before they emerge as adults. Currently, larviciding for nuisance mosquito control is conducted in portions of Electoral Areas ‘A’, ‘J’, ‘L’, ‘O’ and ‘P’, and adulticiding is conducted on a request- only basis in Electoral Areas ‘J’, ‘L’, ‘O’ and ‘P’ (Figure 1). Included in these Electoral Areas (and thus the treatment area) are the municipalities of Kamloops, Barriere, Clearwater, Chase, Logan Lake, Sun Peaks and the Simpcw, Kamloops and Whispering Pines First Nations. The TNRD currently tenders a five-year contract to conduct mosquito control within these Electoral areas, municipalities, and First Nations and provides funds for a contracted staff from April 1 to September 30 each year. In addition, the contract also includes up to 30 hours of helicopter flight time, two days of jet boat use, a four days of ATV use, and mileage for all vehicles and trailers used in the program. The Electoral areas are divided into three geographical areas for funding allocations (Figure 1). The divisions are as follows: 1) Electoral Area ‘A’, consisting of the area just north of Little Fort and north through Blackpool, East Blackpool, and Clearwater to Vavenby along the North Thompson River; 2) Mosquito Area South, consisting of Noble Creek, Sun Peaks, Heffley Creek, Vinsulla, Logan Lake, Pinantan, Pritchard, Cherry Creek, Lac La Jeune, Lac du Bois, greater Kamloops, and the South Thompson River from Kamloops to Chase; and 3) Mosquito Area North, consisting of Black Pines, Whispering Pines, McLure, Barriere, Chinook Cove, Darfield and Little Fort. Each of these areas is monitored by a full-time technician. A forth technician is employed as a “floater” and spends time helping the other technicians as needed.

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Figure 1. Map outlining electoral boundaries and nuisance Mosquito Control Areas within the Thompson-Nicola Regional District.

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1.1. RESOURCES AVAILABLE FOR MOSQUITO CONTROL PROGRAM The TNRD owns and maintains two Leco 500 Ultra-Low Volume (ULV) adulticiding units, one portable Solo backpack ULV sprayer, one London Fog portable aerosol generator, a droplet analyzer for calibrating adulticiding equipment, a Hudson larvicide applicator, seven New Jersey light traps, 40 black-light CDC mosquito traps, a number of backpack granule spreaders and a mosquito control advisory line consisting of a telephone line and answering machine. The Regional District also supplies Aquabac and/or Vectobac (biological larvicides), Altosid (a mosquito growth regulator) and Malathion and resmethrin (adulticides) as needed for mosquito control.

2.0 ENVIRONMENTAL FACTORS

Mosquitoes are similar to most other 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 shallow standing water to mature and pupate. As adult mosquitoes are 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. Due to the relatively arid climate of the TNRD, most larval rearing habitat occurs in temporary snow-melt or river flood-water pools. Snow pack, coupled with temperature and precipitation, are the predominant factors affecting both snow-melt pools and rates and heights of river floods. In the TNRD, the majority of larval habitat for nuisance mosquitoes lies along the North Thompson River.

2.1. SNOW 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 at 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. There are currently four of these stations in

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the North Thompson watershed, and two stations in the South Thompson watershed. The stations with the longest period of record for the two watersheds are Kostal Lake (snow pillow #1E10P, elevation 1770 m) in the North Thompson and Park Mountain (snow pillow #1F03P, elevation 1890 m) in the South Thompson watershed. Data for the last three years from these sites is shown in Figure 2 (North Thompson Kostal Lake) and Figure 3 (South Thompson Park Mountain). Snow pack at Kostal Lake ranged between 62% and 236% of normal between January and June (Figure 2), while levels at Park Mountain ranged between 69% and 189% of normal water equivalents (Figure 3). Snow pack was below average between January and mid-March in both watersheds before increasing to considerably above average for the remainder of the melt. In the North Thompson, this was due primarily to a slightly later than usual melt rather than increased snowfall, while snow continued to accumulate significantly in the South Thompson watershed well into mid-May.

Figure 2. Snow pack at Kostal Lake, in the North Thompson watershed

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Figure 3. Snow pack at Park Mountain, in the South Thompson watershed.

2.1. TEMPERATURE AND PRECIPITATION While the overall volume of snow (described by snow pack) dictates, to a large extent, the total discharge carried through 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. Warmer than average 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 the 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 rapid rises in water level and significant flooding. In 2011, cooler than average temperatures (during both the day and night) from April through July (Figure 4) and above average precipitation levels (Figure 5), resulted in very gradual melting (Figure 6), and a long, sustained, relatively high peak (Table 1).

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Figure 4. Minimum and maximum daily temperatures (°C) measured at Environment Canada weather station Blue River CS (1160H99).

Figure 5. Daily precipitation measured at Environment Canada weather station Blue River CS (1160H99).

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2.2. FLOW LEVELS Flow levels in the North Thompson climbed rapidly through May to a relatively high peak of 1,929 m3/s on May 28th and then remained fairly steady until mid-July when waters slowly began to recede (Figure 6). Table 1 shows the maximum instantaneous discharge for the North Thompson River at McLure between 1998 and 2011. The peak flow in 2010 was higher than the maximum peak measured in any year since 2007, but remained well below maximum flood levels of 1972 and 1999.

Figure 6. Daily flows for 2011 measured on the North Thompson River (WSC Hydrometric Station #08LB064) at McLure Ferry, BC, compared with flows from previous high-water years.

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Table 1. Summary of maximum instantaneous discharge for the North Thompson River at McLure between 1998 and 2011. Maximum instantaneous Date of maximum Year discharge (m3/s) discharge 1998 1,570 May 29 1999 2,590 June 21 2000 1,630 June 10 2001 1,620 May 30 2002 1,920 June 18 2003 1,530 June 11 2004 1,290 June 7 2005 1,870 May 17 2006 2,070 May 25 2007 2,240 June 6 2008 1,920 May 22 2009 1,610 June 7 2010 1,459 May 20 2011 1,929 May 28

3.0 LARVICIDING PROGRAM The majority of the TNRD mosquito control campaign is focused on controlling mosquitoes while they are in their larval stages, for two primary reasons. Firstly, larval control is much more efficient than adulticiding – it is possible to treat larval mosquitoes in very high concentrations in rearing ponds, while adult mosquitoes tend to disperse soon after emerging over a much wider area. Secondly, biological larvicides such as Aquabac and Vectobac are species-specific, affecting only aquatic members of the Order Diptera, which includes mosquitoes, black flies and midges. Adulticides such as malathion and resmethrin are wide-spectrum insecticides, with the ability to kill beneficial as well as pests, and can also be toxic to vertebrates including fish, birds and mammals. Vectobac 200G (PCP 18158, a.i. 2.80%) and Aquabac 200G (PCP 26863, a.i. 2.86%) are the trade name of the biological mosquito larvicides that were used in the TNRD nuisance mosquito control program this year. The active ingredient of these products is the bacterium Bacillus thuringiensis var israelensis (Bti) which is formulated as a granule with crushed corncob as a carrier. The products are effective against mosquitoes and other members of the order Diptera in the larval stage, and are applied by hand, backpack blower or by helicopter to standing water containing significant populations of mosquito larvae. Application rates vary from 3 to 10 kilograms per

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hectare for Vectobac 200G and 3 to 20 kilograms per hectare for Aquabac 200G (with the higher rates applied to polluted or highly organic water), although in 2011, most sites were treated at a rate of 5 kilograms per hectare. Altosid (PCP #21809) is the trade name of a mosquito larvicide that contains the active ingredient methoprene (4.25% 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 in its pupal stage. When methoprene is present in the water, the pupae is not able to develop into an adult and the mosquito dies in its pupal stage. Altosid is formulated in slow-release pellets that release a constant concentration of methoprene into the water for up to 30 days. This larvicide can be applied to dry ground before a flood and will only activate when submerged in water. If the site dries up, the pellets will stop dissolving and will begin to dissolve again if re-submerged. This is the larvicide of choice in habitats such as ditches that become wet intermittently, and in fields where farmers practice flood-irrigation (or over-irrigation) and many generations of mosquito larvae can be produced. In the past, Altosid has been used in two sites in the TNRD with fabulous results: one site west of the Pritchard subdivision and one at Cinnamon Ridge. This year, it was used in Pritchard under the Nuisance Control Program. At the request of the Ministry of Environment, areas containing fish or are permanently contiguous with fish habitat are ineligible for nuisance control treatments, since the larvicide could potentially affect fish productivity by affecting a food source (mosquito larvae). Therefore, only areas that are or will separate from the river or that do not support fish populations are suitable for larviciding. This year a total of 12,719.85 kg of larvicide was applied to 2,286.1 ha of larval development area. Of this, 11,400.9 kg of the larvicide was Vectobac 200G (applied to 2,153.8 ha) and 1,318.95 kg was Aquabac 200G (applied to 132.3 ha). Table 2 shows the historic application of granular larvicide. The amount of larvicide applied in 2011 was the second-highest on record, only slightly less than the 13,030.52 kg we applied in 2003. The hydrometric peak in the North Thompson River was higher than it has been in recent years, and water levels remained high for over a month and a half. The amounts of Bti

BWP Consulting Inc Page 11 2011 Thompson-Nicola Regional District Mosquito Control Program larvicide used and the corresponding areas treated in 2011 are shown in Table 3, Table 4, and Table 5. This spring snowmelt pools had water levels that were slightly lower than in recent years. As occurs every year, these sites were treated in April and early-May. In about the third week of May, the North Thompson reached flood levels, and remained above three meters (the level at which flooding begins) at McLure until the end of July, with the maximum peak occurring on May 28, 2011. The majority of our larviciding activities occurred between June 1 and June 30. As the snow-melt and freshet pools slowly dried up in July and August, treatments, predictably, decreased. Table 2. Historic amounts of granular larvicide (Bacillus thuringiensis var israelensis) used in the TNRD. Year Granular Larvicide (kg) 1989 3,161.00 1990 5,561.00 1991 3,470.00 1992* 1,998.80 1993 2,675.50 1994 4,198.95 1995 3,717.63 1996 7,147.21 1997 8,356.00 1998 3,972.94 1999 9,243.90 2000 9,480.70 2001 7,171.4 2002 12,589.31 2003 13,030.52 2004 9,721.5 2005 10,201.41 2006 12,625.06 2007 11,537.9 2008 9,666.7 2009 11,018.8 2010 5,604.25 2011 12,719.85 *First year Electoral “A” entered the program

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Table 3. Application of Bti Larvicides in Mosquito Area South (Kamloops, Chase, Logan Lake, Areas ‘J’, ‘L’, & part of ‘P’. Apr 1 ‐ Apr 30 May 1 ‐ May 31 June 1 ‐ June 30 July 1 – Aug 31 Totals Larvicide Area Larvicide Area Larvicide Area Larvicide Area Larvicide Area (kg) (ha) (kg) (ha) (kg) (ha) (kg) (ha) (kg) (ha) Barnhartvale 7 1.4 0.5 0.1 7.5 1.5 Chase 3.5 0.5 117.4 23.48 0.3 0.06 121.2 24.04 Cherry Creek 10 1.4 10 1.4 Heffley Creek 18.1 3.62 18.1 3.62 Knutsford 25 5 441.4 48.19 466.4 53.19 Lac Du Bois 22 4.4 22 4.4 Lac La Jeune 16.5 3.3 16.5 3.3 Community Lac Le Jeune 33 6.6 199.1 19.91 232.1 26.51 Logan Lake 230.45 41.59 7 1.4 2 0.4 239.45 43.39 Noble Creek 15 3 72.4 14.48 15 3 102.4 20.48 North Thompson 153.8 16.28 129.2 25.84 10 2 293 44.12 Paul Lake 179.3 17.95 179.3 17.95 Pinantan Lake 641.8 64.67 641.8 64.67 Pritchard 62.75 12.55 4.5 0.9 60.3 12.06 127.55 25.51 Rayleigh 12 2.4 54.3 10.86 66.3 13.26 Rose Hill 0.25 0.025 0.25 0.025 Sun Peaks 52.2 6.24 791.8 158.4 2 0.4 846 165.04 Thompson 234.2 25.12 554.9 111 5 1 794.1 137.12 Vinsulla 90.5 18.1 90.5 18.1 Total: 142.75 28.55 2,201 252.875 1,896.4 379.34 34.3 6.86 4,274.45 667.625

Table 4. Application of Bti Larvicides in Mosquito Area North (Area ‘O’ and part of ‘P’). Apr 1 ‐ Apr 30 May 1 ‐ May 31 June 1 ‐ June 30 July 1 – Aug. 31 Totals Larvicide Area Larvicide Area Larvicide Area Larvicide Area Larvicide Area (kg) (ha) (kg) (ha) (kg) (ha) (kg) (ha) (kg) (ha) Barriere 137.7 14.87 348.9 69.8 486.6 84.67 Blackpines 98.5 10.65 74.9 14.98 7 1.4 180.4 27.03 Chinook Cove 19 3.8 54.3 10.86 73.3 14.66 Chu Chua Indian Band 144.8 28.96 149.8 15.48 687.8 137.6 982.4 182 Darfield 207.8 27.08 1,015.1 203 1 0.2 1,223.9 230.3 Little Fort 4 0.8 622.4 124.48 626.4 125.28 McLure 226.1 25.31 144.8 28.92 5 1 375.9 55.23 Total: 144.8 28.96 842.9 97.99 2,948.2 589.6 13 2.6 3,948.9 719.17

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Table 5. Application of Bti Larvicides in Electoral Area ‘A’ Apr 1 ‐ Apr 30 May 1 ‐ May 31 June 1 ‐ June 30 July 1 – Aug. 31 Total Larvicide Area Larvicide Area Larvicide Area Larvicide Area Larvicide Area (kg) (ha) (kg) (ha) (kg) (ha) (kg) (ha) (kg) (ha) Birch Island 276 55.2 316 63.2 592 118.4 Blackpool 1,616.5 323.3 919 183.8 8 1.6 2,543.5 508.7 Clearwater 336 67.2 125.5 25.1 0 0 461.5 92.3 East Blackpool 643.5 128.7 144 28.8 5 1 792.5 158.5 Upper 72 14.4 0 0 0 0 72 14.4 Clearwater Vavenby 31 6.2 4 0.8 35 7 Total 2,944 588.8 1,535.5 307.1 17 3.4 4,496.5 899.3

3.1. HAND APPLICATION OF LARVICIDE Hand application of Vectobac 200G was initiated in early April, and continued until mid-August. A total of 600.4 kg of Vectobac 200G was applied by hand and backpack blower to 91.12 ha of larval development habitat in the Mosquito Control Area North. The hand treatment was mostly in small sites as “mop-up” before and after helicopter campaigns although many sites had multiple generations of larvae and most of these were treated by hand at least once as well. In Mosquito Area South, hand and backpack blower treatments involved the application of 763.15 kg of larvicide to 131.825 ha of larval development habitat (16.25 kg of Aquabac 200G and 746.9 kg of Vectobac 200G). The most heavily hand treated areas in Mosquito Area South were Logan Lake, Knutsford, and Pritchard. In addition to the Vectobac, 16 kg of Altosid Pellets were applied by hand to 1.6 ha of larval development habitat in the Pritchard area. Finally, in Electoral Area “A”, 536.5 kg of Vectobac 200G were applied by hand or backpack blower to 107.3 ha of larval development area. The most heavily treated area was Blackpool, which received 288.5 kg of larvicide.

3.2. HELICOPTER APPLICATION OF LARVICIDE Our company employed CC Helicopters, based in Kamloops, for surveillance and larviciding applications to all regions of the TNRD. Pilot, Katie McMillian, flew all helicopter applications in 2011.

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3.2.1. Snowmelt and Grassland Applications A helicopter campaign was conducted on May 3, 2011 to treat areas of Paul Lake, Pinantan, Knutsford and Lac Le Jeune. A total of 1,303.2 kg of Aquabac 200G larvicide was applied to 130.32 ha of larval development habitat.

3.2.2. North and South Thompson Floodwater Applications The highest peak of the North Thompson River occurred on May 28th at 4.29 m (1,929 m3/sec) (at McLure Ferry) (Figure 7). Many of our sites begin to activate when the river level reaches approximately 3.0 m, which first occurred on May 16th. The first helicopter treatment for floodwaters along the North Thompson occurred on May 24 on the North Thompson between Birch Island and the City of Kamloops, including Clearwater, Blackpool, East Blackpool, Little Fort, Darfield, the Chu Chua Indian Reserve, Blackpines, McLure, Noble Creek, Vinsulla, and the Thompson River in Kamloops, where 3,340.3 kg of Vectobac 200G was applied to 590.23 ha of habitat. On June 3rd and 4th, we used 4,269.1 kg of Vectobac 200G to treat 853.82 ha of area between Birch Island and the City of Kamloops, including Clearwater, Blackpool, East Blackpool, Little Fort, Darfield, the Chu Chua Indian Reserve, Blackpines, McLure, Noble Creek, Vinsulla, and the Thompson River in Kamloops. On June 8th, a helicopter campaign was conducted along the South Thompson River and around the Village of Sun Peaks, where 941.2 kg of Vectobac 200G was applied to 188.28 ha of land. The majority of the application occurred in Sun Peaks. Finally, on June 29th, a small campaign was conducted in Area A, from Birch Island to Blackpool, where 966 kg of Vectobac 200G was applied to 193.2 ha of habitat.

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Figure 7. Hydrograph of the North Thompson River at McLure showing dates of 2011 helicopter larviciding applications.

4.0 ADULTICIDING PROGRAM

The TNRD Mosquito Adulticiding Program is facilitated by the use of two truck- mounted Leco 500 Ultra-Low Volume (ULV) sprayers and one portable Solo backpack ULV sprayer. Both Malathion and resmethrin can be used in these sprayers. Historically, aerial and ground application of these pesticides constituted the primary means of controlling mosquito populations, and large amounts were used annually. However, more recently, due to environmental concerns associated with the toxicity of adulticides such as Malathion and resmethrin, application of these pesticides has occurred on a much smaller scale, and only in response to specific requests. Adulticides are used only in Electoral Areas ‘J’. ‘L’, ‘O’ and ‘P’, as residents in Electoral Area ‘A’ elected to

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ban the spraying of insecticides for mosquito control. For residents living within Electoral Areas ‘J’, ‘L’, ‘O’ and ‘P’ where property belonging to more than one landowner is to be treated, petitions are required and must be signed by all property owners in the treatment areas. Care is taken to ensure that property owners who do not wish to be treated receive no pesticide whatsoever, and therefore buffer zones are established around such areas. Similarly, due to the high toxicity of Malathion and resmethrin to fish species, no-pesticide zones and buffer zones are established around fish-bearing areas such as the North and South Thompson rivers, and tributaries to these rivers. Spraying is conducted between dusk and dawn, to minimize impacts to beneficial insects and exposure to humans and domestic . Instructions are given to landowners prior to a spray campaign to keep windows and doors shut, turn air- conditioners and fans off, and keep pets in the house or under cover, if at all possible.

4.1. CALIBRATION OF ULV SPRAYERS There were no requests for the use of adulticides this summer. Calibration typically takes 30 to 60 minutes in the field, and in our professional opinion, it is best done at a proposed spray location the night of a spray event (or the night before). This means that the equipment would be calibrated at a location where adulticiding is warranted and in accordance with all of the requirements of the TNRD Nuisance PMP. In the past, the equipment has been calibrated during daylight hours in a remote location, however, technically, this activity could be challenged since the release of malathion is occurring in an area that does not contain mosquitoes and during daylight hours. The results of the 2008 calibration activities were reviewed in early 2011 and the equipment has not been used since the calibration. Also, it should be noted that the word “calibration” implies that adjustments were made to the equipment in 2008, when in actuality, the flow tests and droplet analysis showed that no adjustments were required on the equipment in 2008. The following paragraph outlines the procedure and results of the 2008 “calibration”. Gardex Malathion ULV 95% concentrate (PCP 16198) was used to assess the flow rate and droplet size of Leco truck-mounted sprayers. On each of these units only a single trial was necessary to confirm the droplet size and flow rate were within proper ranges. They were both calibrated in 2007 and have not been used since. The flow tests

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were conducted for 30 seconds by pumping pesticide directly into a graduated cylinder and then the volume per minute (multiply by two) was calculated. Once the flow rates were confirmed, the units were tested for droplet size output. In 2007, marks were made on the Leco 500 units to show where the engines should be set to attain the appropriate spray “pressure” which produces the appropriate droplet size. These marks worked well and only one trial was need for each machine to confirm a droplet size within the Malathion label recommendations for mosquito control (Table 6). Table 6. Results of calibration activities for adulticiding equipment. Mass Median Max Minimum (volume) Diameter of diameter diameter Adulticiding Unit Pesticide Used Flow Rate droplets (microns) (microns) (microns) Malathion Leco 500 ULV (red) 90 ml/min 16.31 38 1 (PCP 16198) Malathion Leco 500 ULV (black) 90 ml/min 16.80 43 1 (PCP 16198)

The DCIII droplet analyzer was sent to the manufacturer for maintenance and calibration in October of 2009 and it is therefore certified as accurate.

4.2. APPLICATION OF ADULTICIDES Adulticide was not applied this year. This is the ninth year in a row and the tenth of our thirteen years of service in which the goal of no adulticiding has been met. This is directly attributable to dedicated crews and their exceptional larviciding efforts and to increased public education whereby landowners assist our crews to larvicide in a timely manner. Historical amounts of adulticide applied in the TNRD can be found in Table 7.

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Table 7. Volumes of Malathion and Resmethrin used in the TNRD since 1989. Year Malathion (L) Resmethrin (L) 1989 63.70 1990 419.50 1991 5.50 1992 17.01 1993 136.99 1994 0.63 1995 107.79 1996 38.71 28.11 1997 45.44 0.20 1998 1.88 4.00 1999 79.44 2000 0.741 2001 0 2002 27.404 2003 0 2004 0 2005 0 2006 0 2007 0 2008 0 2009 0 2010 0 2011 0

5.0 LIGHT TRAPS

This year, the TNRD employed seven New Jersey Light traps throughout the mosquito control areas. The traps are designed to attract mosquitoes with light and chemical attractants. When the mosquitoes approach the trap, a fan sucks them into a jar containing an insecticide. Each of the traps are usually employed for 8-9 weeks, however they were run for 10 weeks this year using supplemental funding from the West Nile Virus (WNV) program. Technicians collect the insects in the trap on a weekly basis. This year the locations of the traps were as follows: (1) Clearwater at the residence of Arvinder Heer on Helmcken Street; (2) Blackpool, next to the Blackpool Wildlife Sanctuary; (3) East Blackpool at the residence of Mr. Schuler; (4) Darfield at MacColl Rd; (5) McLure at the residence of Bob Hearn; (6) Noble Creek at the residence of Edward Babcock, and (7) at the Kamloops Waste Water Treatment Plant (WWTP). These locations were the same ones used since 2007, with the exception of the

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Clearwater trap, which was moved from Archibald St. to Helmcken St, and the East Blackpool trap, which moved from Mr. Grenier’s residence to Mr. Schuler’s residence. This year, dry ice was used consistently in the Kamloops, Noble Creek, McLure and Darfield traps and was used occasionally in the Clearwater, Blackpool and East Blackpool traps. Dry ice is a powerful mosquito attractant as it sublimates to carbon dioxide and mimics mammal and bird breathe. Light traps were initially set on June 11th in Area ‘A” and on June 8th in the other areas. Insects collected in the traps were delivered to Kamloops. Mosquitoes were then separated from other insects caught in the trap, and identified to species. Information gathered from identifying the specimens captured in these traps can be used to give an indication of the size of the mosquito populations, the type of larval development habitat supporting the populations, and the hosts of the mosquito species present. This information may also become useful when determining areas where WNV vector mosquitoes are present in the event that an outbreak such as WNV occurs.

5.1. ANALYSIS OF 2011 LIGHT TRAP CATCHES This year, trap counts were higher than in recent years, especially at McLure and the WWTP sites. Since 2007, dry ice has been utilized as an additional attractant in the light traps, significantly boosting trap counts over the past two years. The relatively high water levels this year, coupled with the long duration of the flood, meant that extensive larval development habitat existed for significant periods of time this summer, making treatment of larvae difficult. Trap counts and species distributions are summarized in Table 8 to Table 14. The total number of mosquitoes captured this year was up considerably from last year (7,208 mosquitoes in 2011, compared with only 1,178 mosquitoes in 2010), and trap counts per night were higher in the southern sites. However, much of this increase was due to large increases at both the WWTP and McLure sites. Numbers at the traps in Area A were fairly low. This year, the highest numbers of mosquitoes were captured in the WWTP trap and not in Blackpool or East Blackpool as is traditionally the case. The average trap count per night for the three traps in Area “A” was 1.7 mosquitoes per night (Table 16). This is considerably lower than the average of 2.2

BWP Consulting Inc Page 20 2011 Thompson-Nicola Regional District Mosquito Control Program mosquitoes in 2010, 10.5 mosquitoes per night captured in 2009 or the 35.3 mosquitoes per night captured in 2008, and comparable to the 1.1 mosquitoes per night captured in 2004. The relocation of the trap in East Blackpool could account for some of the decrease in count numbers. The majority of the mosquitoes collected in Area ‘A’ were floodwater species of the genera Ochlerotatus and Aedes (85% of the total catch). The most prevalent species in Area ‘A’ was Aedes vexans, a species that is considered the worst nuisance mosquito in British Columbia (152 specimens, or 50% of identifiable mosquitoes captured in Area ‘A’). In the traps located in Mosquito Area North and Mosquito Area South, the average nightly catch was 24.8 mosquitoes, up considerably from the 2.2 mosquitoes per night in 2010, the 1.7 mosquitoes per night in 2009, the 13.3 mosquitoes per night captured in 2008 and the 19.1 mosquitoes per night captured in 2007 (Table 16). As in Area ‘A’, the primary species was Culex tarsalis (2,501 of 5,045 individuals captured, representing 50% of identifiable mosquitoes). Culex tarsalis is the primary species of concern with respect to West Nile Virus transmission, and will be a concern should the virus reach the interior of British Columbia, however it is not considered a nuisance mosquito as it is not usually an aggressive biter of humans. Twenty-two species from all six genera present in British Columbia were identified this year (Table 15). Unlike most years, when Aedes vexans is the most abundant species captured, Culex tarsalis was the most abundant species, representing 47% of the overall identifiable catch (Table 15). When the eleven Aedes and Ochlerotatus (floodwater) species counts were tallied, they comprised approximately 34% of the total catch (1,798 specimens). Culex mosquitoes made up 52% of the total catch (2,782 specimens, compared with 307 specimens in 2010, 114 specimens in 2009, 387 specimens in 2008, 839 specimens in 2007 and 716 specimens in 2006). Culiseta mosquitoes made up about 13% of the total catch (715 specimens), and Anopheles mosquitoes and Coquillettidia perturbans each comprised less than 1% of the catch (29 specimens and 25 specimens, respectively) (Table 15). The WNV vector species Culex tarsalis was present in all trapping locations and was very abundant at the Waste Water Treatment Plant and McLure locations (Table 15). Culex pipiens, another important WNV vector, was also found in significant numbers at

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the WWTP. These mosquitoes appeared in the traps primarily in late July and August and would not normally have been captured since surveillance for nuisance mosquitoes is generally concluded by this time of the year. Table 8. Mosquito specimens collected in the New Jersey light trap at the Waste Water Treatment Plant in Kamloops, BC. Date (2011) Jun Jun Jun Jul Jul Jul Jul Aug Aug Aug Species Total 17 21 29 07 13 20 27 03 10 18 Aedes vexans 10 6 29 14 8 6 3 6 3 85 Anopheles freeborni 1 1 Culex pipiens 4 3 5 204 6 222 Culex tarsalis 10 14 27 743 345 119 145 138 132 1,673 Culiseta incidens 12 12 Culiseta inornata 1 3 15 5 16 36 16 92 Ochlerotatus dorsalis 2 21 4 27 Ochlerotatus increpitus 2 2 Ochlerotatus sticticus 1 5 4 3 3 16 Mosquito unidentifiable* 581 3 584 Ochlerotatus male unidentified** 2 4 48 70 67 62 149 257 214 873 Total Number Captured 23 27 134 581 827 447 200 321 653 374 3,587 No of males (out of total above) 13 10 89 659 344 163 267 473 255 2,273 *Specimen too damaged to be identified **Ochlerotatus males can be difficult to identify Table 9. Mosquito specimens collected in the New Jersey light trap in Noble Creek, BC. Date (2011) Jun Jun Jun Jul Jul Jul Jul Aug Aug Aug Species Total 17 21 29 07 13 20 27 03 10 18 Aedes cinereus 2 1 3 Aedes vexans 112 1 96 94 38 3 4 348 Anopheles earlei 1 2 3 Anopheles freeborni 1 1 Culex pipiens 1 1 1 3 Culex tarsalis 1 11 18 8 1 3 42 Culiseta inornata 1 9 35 8 3 9 2 67 Ochlerotatus dorsalis 1 4 5 Ochlerotatus excrucians 2 2 Ochlerotatus increpitus 2 4 6 sample mouldy mouldy sample mouldy sample Ochlerotatus punctor 1 1 Ochlerotatus spencerii var spencerii 1 1 Ochlerotatus sticticus 7 11 1 1 20 Mosquito unidentifiable* 4 7 1 1 13 Ochlerotatus male unidentified** 15 5 25 18 5 68 Total Number Captured 130 1 132 199 0 83 4 21 13 0 583 No of males (out of total above) 122 72 65 22 5 4 290 *Specimen too damaged to be identified **Ochlerotatus males can be difficult to identify

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Table 10. Mosquito specimens collected in the New Jersey light trap in McLure, BC. Date (2011) Jun Jun Jun Jul Jul Jul Jul Aug Aug Aug Species Total 12 21 29 07 13 20 27 03 10 18 Aedes cinereus 1 8 3 1 13 Aedes vexans 5 5 82 12 221 235 88 71 61 64 844 Anopheles earlei 1 2 6 3 2 3 17 Anopheles freeborni 4 4 Anopheles punctipennis 3 3 Coquillettidia perturbans 2 8 4 1 9 24 Culex pipiens 3 19 22 Culex tarsalis 1 5 6 3 25 63 124 167 229 151 774 Culiseta incidens 1 3 1 11 16 Culiseta inornata 1 8 18 23 64 229 170 513 Ochlerotatus dorsalis 1 1 Ochlerotatus fitchii 2 2 Ochlerotatus spencerii var spencerii 3 3 Ochlerotatus sticticus 87 8 2 2 8 107 Mosquito unidentifiable* 58 5 4 67 Ochlerotatus male unidentified** 1 63 18 34 116 Total Number Captured 8 11 89 142 355 347 270 315 528 461 2,526 No of males (out of total above) 2 2 60 63 171 121 90 101 178 94 882 *Specimen too damaged to be identified **Ochlerotatus males can be difficult to identify Table 11. Mosquito specimens collected in the New Jersey light trap in Darfield, BC. Date (2011) Jun Jun Jun Jul Jul Jul Jul Aug Aug Aug Species Total 17 21 29 07 13 20 27 03 10 18 Aedes cinereus 2 2 Aedes vexans 2 7 4 13 14 1 1 42 Culex tarsalis 1 2 3 3 3 12 Culiseta inornata 2 2 4 Ochlerotatus fitchii 1 1 Ochlerotatus implicatus 2 2 Ochlerotatus increpitus 1 1 Ochlerotatus sierrensis 1 1 Ochlerotatus sticticus 5 damaged sample 5 No mosquitoes seen seen No mosquitoes Mosquito unidentifiable* 1 4 1 4 1 2 13 Ochlerotatus male unidentified** 10 20 27 1 3 61 Total Number Captured 2 0 11 27 0 1 42 48 7 6 144 No of males (out of total above) 2 2 13 4 39 1 61 *Specimen too damaged to be identified **Ochlerotatus males can be difficult to identify

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Table 12. Mosquito specimens collected in the New Jersey light trap in East Blackpool, BC. Date (2011) Jun Jun Jun Jul Jul Jul Jul Aug Aug Aug Species Total 17 24 30 11 15 22 29 08 15 22 Culex tarsalis 1 1 Culiseta inornata 1 1 Aedes vexans 1 3 4 No mosquitoes Ochlerotatus implicatus 2 2 4

seen seen Ochlerotatus sticticus 2 3 1 6 Mosquito unidentifiable* 1 1 No mosquitoes No mosquitoes Ochlerotatus male unidentified** 2 1 2 5 Total Number Captured 0 4 4 7 2 4 1 0 0 0 22 No of males (out of total above) 2 1 2 5 **Ochlerotatus males can be difficult to identify

Table 13. Mosquito specimens collected in the New Jersey light trap near the Roundtop Road Wildlife Sanctuary in Blackpool, BC. Date (2011) Jun Jun Jun Jul Jul Jul Jul Aug Aug Aug Species Total 17 24 30 11 15 22 29 08 15 22 Aedes cinereus 1 2 4 7 Aedes vexans 12 60 31 7 7 11 7 3 2 140 Culex pipiens 1 1 Culex tarsalis 1 1 2 Culiseta incidens 1 1 Culiseta minnesotae 1 1 Ochlerotatus dorsalis 2 2 Ochlerotatus implicatus 6 13 1 5 25 Ochlerotatus sticticus 35 3 5 2 1 1 47 No mosquitoes seen seen No mosquitoes Mosquito unidentifiable* 1 3 2 6 Ochlerotatus male unidentified** 5 42 2 2 51 Total Number Captured 18 148 52 16 16 19 8 4 0 2 283 No of males (out of total above) 15 42 3 3 4 6 2 2 77 *Specimen too damaged to be identified **Ochlerotatus males can be difficult to identify

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Table 14. Mosquito specimens collected in the New Jersey light trap in Clearwater, B.C. Date (2011) Jun Jun Jun Jul Jul Jul Jul Aug Aug Aug Species Total 17 24 30 01 15 22 29 08 15 22 Aedes cinereus 1 1 1 3 Aedes vexans 1 2 2 3 8 Coquillettidia perturbans 1 1 Culex pipiens 1 1 1 3 Culex tarsalis 2 1 5 7 6 5 1 27 Culiseta alaskaensis 1 1 Culiseta incidens 1 2 3 Culiseta inornata 2 1 3 Culiseta morsitans 1 1 Ochlerotatus implicatus 2 1 1 4

Ochlerotatus increpitus seen No mosquitoes 1 1 Ochlerotatus sierrensis 1 1 2 Ochlerotatus sticticus 1 1 3 5 Ochlerotatus male unidentified* 1 1 Total Number Captured 0 4 2 3 2 8 16 14 8 6 63 No of males (out of total above) 1 1 2 1 3 2 3 13 *Ochlerotatus males can be difficult to identify

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Table 15. Number of mosquitoes trapped in each of the New Jersey Light Traps.

r Clearwate TNRD: Blackpool TNRD: Blackpool TNRD: E. Blackpool TNRD: Darfield TNRD: McLure Creek TNRD: Noble WWTP Kamloops: Totals Aedes cinereus*** 3 7 0 2 13 3 0 28 Aedes vexans*** 8 140 4 42 844 348 85 1,471 Anopheles earlei*** 0 0 0 0 17 3 0 20 Anopheles freeborni 0 0 0 0 4 1 1 6 Anopheles punctipennis*** 0 0 0 0 3 0 0 3 Coquillettidia perturbans*** 1 0 0 0 24 0 0 25 Culex pipiens*** 3 1 0 0 22 3 222 251 Culex tarsalis*** 27 2 1 12 774 42 1,673 2,531 Culiseta alaskaensis 1 0 0 0 0 0 0 1 Culiseta incidens*** 3 1 0 0 16 0 12 32 Culiseta inornata*** 3 0 1 4 513 67 92 680 Culiseta minnesotae 0 1 0 0 0 0 0 1 Culiseta morsitans*** 1 0 0 0 0 0 0 1 Ochlerotatus dorsalis*** 0 2 0 0 1 5 27 35 Ochlerotatus excrucians 0 0 0 0 0 2 0 2 Ochlerotatus fitchii 0 0 0 1 2 0 0 3 Ochlerotatus implicatus 4 25 4 2 0 0 0 35 Ochlerotatus increpitus 1 0 0 1 0 6 2 10 Ochlerotatus punctor 0 0 0 0 0 1 0 1 Ochlerotatus sierrensis*** 2 0 0 1 0 0 0 3 Ochlerotatus spencerii var spencerii 0 0 0 0 3 1 0 4 Ochlerotatus sticticus*** 5 47 6 5 107 20 16 206 Mosquito unidentifiable* 0 6 1 13 67 13 584 684 Ochlerotatus male unidentified** 1 51 5 61 116 68 873 1,175 Total number captured 63 283 22 144 2,526 583 3,587 7,208 No. trap nights 72 72 72 71 71 63 71 492 Ave. catch/night 0.9 3.93 0.31 2.03 35.58 9.25 50.52 14.65 *Specimen too damaged to be identified **Ochlerotatus males can be difficult to identify ***Mosquito species included on Peter Belton’s list of British Columbia Mosquitoes as Vectors of West Nile Virus.

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Table 16. Historic numbers of mosquitoes trapped per night in Areas ‘J’, ‘L’, ‘O’ and ‘P’, and Area ‘A’. Trapping sites vary over the years, as do overall trapping periods and attractants used. Year Areas ‘J’, ‘L’, ‘O’ and Area ‘A’ ‘P’ 1989 3.4 1990 8.1 1991 2.0 1992* 0.2 1993 10.2 73.1 1994 1.2 5.4 1995 5.4 6.3 1996 7.3 13.1 1997 2.5 18.0 1998 0.3 3.1 1999 3.3 7.4 2000 0.1 0.6 2001 0.3 0.1 2002 11.5 7.1 2003 1.8 7.3 2004 2.6 1.7 2005 1.6 12.5 2006 3.7 11.2 2007** 19.1 15.5 2008** 13.3 35.3 2009** 1.7 10.5 2010** 2.2 2.1 2011** 24.8 1.7 *First year Electoral “A” entered the program ** Dry ice used in all traps once per week

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6.0 BIOLOGY OF MAJOR MOSQUITO SPECIES COLLECTED

6.1. AEDINES IN GENERAL Until recently, all of the “floodwater” (i.e., laying their eggs on moist soil rather than on the water’s surface) species of mosquitoes in BC were classified as Aedes, but a number of species have now been reclassified into the genus Ochlerotatus. However, the life cycle of Aedes and Ochlerotatus species are similar. Aёdes is the Greek word for disagreeable (Belton, 1983), and is an accurate reflection of these species in terms of both numbers and ferocity. Aedes and Ochlerotatus species lay their eggs at the edges of water bodies and rely on warm temperature and/or low oxygen level in flood-water to hatch. Most of the floodwater species peak in late June (following snowmelt and then river flooding) and die in late summer and the populations over-winter as eggs. Mosquitoes that are viewed as nuisance species (i.e. present in high numbers and biting ferociously) are generally from this group, as large areas of habitat often become active at once with rising floodwaters and therefore huge batches of mosquitoes hatch at the same time. This is due primarily to the fact that eggs laid by most species remain viable for a number of years, and therefore egg concentrations in the soil can become very dense. Adults are generally short-lived (two to six weeks), and generally seek shade during hot summer days as they are prone to desiccation. Most species have only one generation each year, although some species are capable of two or more generations when conditions are suitable. This year eleven different species of Aedes and Ochlerotatus species were trapped and they composed about 35% of the individuals caught in the TNRD light traps. The major Aedine species captured this year in the TNRD was Aedes vexans (Table 15).

6.1.1. Aedes cinereus Aedes cinereus is present throughout British Columbia and is capable of completing up to three generations per year (Belton, 1983; Wood et al., 1979). Larvae have been found in rain pools, swamps and flood water (Belton, 1983). This species is not likely to known to fly any great distance, and is generally considered a minor pest although isolated populations may be aggressive and persistent biters, even during the heat of the day (Belton, 1983). This species appears on Belton’s (2007) list of potential West Nile Virus vectors, with a low vector competency.

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This year, Aedes cinereus were present in low numbers in Clearwater, Blackpool, Darfield and McLure.

6.1.2. Aedes vexans This mosquito species is considered the worst mosquito pest in Canada (Wood et al., 1979). Aedes vexans appear in extremely large numbers in almost any habitat where there are permanent, semi-permanent, or transient pools that have been flooded from snowmelt or rain. In the heat of summer, these mosquitoes can mature from the egg to adult in as short as five days, existing as larvae for as little as three days (Wood et al., 1979). Eggs of Aedes vexans can remain viable in the soil for many years, and because not all individuals hatch when inundated, multiple cycles of flooding and drying are needed for all eggs to hatch (Wood et al., 1979). Adult Aedes vexans are notorious fliers, capable of flying as far as 20 to 50 km or riding low jet streams for hundreds of kilometres, and are vicious biters as well (Belton, 1983). This can make control difficult to say the least. Specimens of Aedes vexans have been found carrying the western equine encephalitis (WEE) virus in Alberta, Saskatchewan and north western United States (Belton, 1983). Belton (2007) has included Aedes vexans as a potential West Nile Virus vector with a vector competence rating of low since specimen of this mosquito have occasionally tested positive for the virus. However, since Aedes vexans rarely take more than one blood meal, they are highly unlikely to be vectors of WNV. Aedes vexans was captured in each of the traps deployed this year, and was the dominant species in Blackpool, McLure and Noble Creek. The total number of specimens from all traps this year was 1,474 (Table 15), more than the 712 individuals captured in 2010 but considerably fewer than the 2,516 specimens caught in 2009, the 8,491 specimens captured in 2008 or the 6,952 individuals captured in 2007. About 81% of the Aedes vexans captured this year were in the Blackpool and McLure traps.

6.1.3. Ochlerotatus dorsalis This species thrives on the interior plateau, breeding in saline swamps and pools as well as fresh water (especially irrigation seepages) (Belton, 1983). It is capable of traveling many kilometers, and females of this species are vicious biters both during the day and at night (Belton, 1983). When conditions are favourable, Ochlerotatus dorsalis may have two or more summer generations, resulting in a very large population (Wood et

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al. 1979). Belton (2007) gives Ochlerotatus dorsalis a vector competence rating of ‘+++’, primarily because Western Equine Encephalitis and West Nile Virus have occasionally been isolated in adult females. Low numbers of this species were found at the WWTP, Noble Creek, McLure and Blackpool sites.

6.1.4. Ochlerotatus excrucians Ochlerotatus excrucians can be found throughout Canada south of the arctic tundra (Woods et al., 1979). Larvae of this species can be found in almost any ground pool, but seem to prefer the edges of larger semi-permanent marshes. Adults are large in size and will survive well into late summer. When present females are fierce biters, but rarely occur in large numbers in British Columbia (Belton, 1983). This species does not appear on the list of potential WNV vectors (Belton, 2007). It was found in very low numbers at the Noble Creek site.

6.1.5. Ochlerotatus fitchii Ochlerotatus fitchii occur nearly everywhere in Canada south of the tree-line, (Woods et al.,1979). Larvae of this species are often collected in the same locations as the larvae of Ochlerotatus excrucians or early in the spring in snowmelt pools with Ochlerotatus increpitus (Belton, 1983; Woods et al., 1979). It is described as an aggressive pest mosquito of the southern interior and can be a nuisance at elevations as high as 1500m (Belton, 1983). Although individuals of this species have been found infected with WNV, they are unlikely to transmit the illness. Low numbers of this species were found in Darfield and McLure.

6.1.6. Ochlerotatus implicatus Ochlerotatus implicatus is one of the earliest species to emerge as adults, breeding in temporary snow or rain pools in woodland areas (Belton, 1983; Wood et al. 1979). It is one of the most widely distributed species in Canada south of the tree line, but is seldom found in high enough concentrations to be considered a nuisance (Wood et al. 1979). Adults tend to be short lived, and while it bites vigorously in shaded conditions during the day, its low numbers make it generally not significant (Belton, 1983). Belton (2007) does not include this species on his list of potential WNV vectors. Low numbers were found in Clearwater, Blackpool, East Blackpool and Darfield.

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6.1.7. Ochlerotatus increpitus Ochlerotatus increpitus is fairly widespread and numerous throughout BC, with larvae found in flood waters, irrigation seepage and rain or snowmelt pools (Belton, 1983) as well as roadside ditches and shaded pools (Wood et al. 1979). While female Ochlerotatus increpitus are an important pest in Nevada and Utah, they are generally not common enough in Canada to be considered a significant pest (Wood et al. 1979). However, in those localized areas of BC where large numbers are found, the females are eager biters and can be a serious pest of cattle (Belton, 1983). Belton (2007) does not include this species on his list of potential WNV vectors. A few specimens were found in Clearwater, Darfield, Noble Creek and at the WWTP.

6.1.8. Ochlerotatus punctor Ochlerotatus punctor is an early spring species, hatching and developing under ice and emerging as one of the first adult mosquito species (Belton, 1983). It is found almost exclusively in coniferous forest pools, usually associated with sphagnum bogs (Wood et al. 1979). Males occasionally congregate in huge swarms over landmarks such as roads or railway tracks (Belton, 1983; Wood et al. 1979). It is considered a vicious and persistent biter and a serious pest of man and animals in wooded areas (Belton, 1983). Belton (2007) does not include this species on his list of potential WNV vectors. One specimen was found at the Noble Creek site.

6.1.9. Ochlerotatus sierrensis Ochlerotatus sierrensis larvae develop in tree-holes. Larvae have also been found in tires and hollow stumps in the province (Woods et al., 1979). As this species rarely occurs in high numbers, it is not considered a significant pest in British Columbia. Peter Belton (2007) includes this species on his list of potential vectors, with a rating of “+”. Two specimens were found in the Clearwater trap, and one in Darfield.

6.1.10. Ochlerotatus spencerii (both variants) Ochlerotatus spencerii larvae can be found very early in the spring, and then throughout the summer. They can be found in snow and rain pools, irrigation seepage, and floodwater sites (Belton, 1983). In the interior of BC, they have been found in the same pools as Aedes vexans and Ochlerotatus dorsalis. When this mosquito is present in

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high numbers, it can be an aggressive and persistent biter, even during the heat of the day. There are two variants of this species in BC, idahoensis and spencerii. The difference between these two variants lies in the markings present on their tergites (the main body segments). A few specimens of Ochlerotatus spencerii var. spencerii were found in McLure and Noble Creek.

6.1.11. Ochlerotatus sticticus Ochlerotatus sticticus is primarily a floodwater mosquito and is therefore usually associated with the floodplains of large rivers and widespread excessive precipitation (Wood et al., 1979). This pest was highest in numbers in the East Blackpool trap, which is consistent with other years and is not surprising as this trap is positioned very close to the North Thompson River and is surrounded by flooded forest and fields when the river peaks. With each peak of a river, a fresh hatch of Ochlerotatus sticticus can appear (Belton, 1983). This species is almost always associated with Aedes vexans (Wood et al., 1979). Eggs of Ochlerotatus sticticus can remain viable for about five years, so there may be years when this species may not appear at all as it waits for a significant flood (Belton, 1983). This was the case in 2003 and 2004, as well as this year, when very few specimens of this species were captured. Like Aedes vexans, Ochlerotatus sticticus are ferocious biters and readily enter houses day and night (Belton, 1983). It was found at all of the sites, and in relatively high numbers (>100 specimens) at the McLure site.

6.2. CULEX SPECIES Culex is the Latin word for mosquitoes and was used to describe all mosquito species prior to 1818, when the genera Anopheles and Aedes were added (Belton, 1983). There are only three species of Culex in BC (Culex tarsalis, Culex pipiens and Culex territans). Culex females lay their eggs in rafts on the surface of almost any water, and all species found in BC overwinter as fertilized females. As well, all Culex species in BC can produce several generations a year, providing the summer is warm enough. These mosquitoes are generally not considered a nuisance as they are usually in lower concentrations and are not particularly vicious biters. Because they have multiple broods in their lifetime, they have the potential to transmit viruses such as the various encephalitites and WNV. This is because they must take a blood meal before laying each batch of eggs, and, after feeding on an infected host, the female has the potential to

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transmit the virus to her next host. Two of BC’s three Culex species were found in the TNRD this year.

6.2.1. Culex tarsalis Culex tarsalis breeds in permanent and semi-permanent ponds, irrigation ditches and sewage ponds (Belton, 1983), spreading to small temporary pools and artificial containers as numbers increase through the summer (Wood et al., 1979). In general, they prefer warm, stagnant water with a high concentration of organic materials. Culex tarsalis overwinters as adults, hiding in caves, rock piles and talus slopes. Adults feed primarily between sunset and sunrise, with peak activity occurring within two hours after sunset (Wood et al., 1979). This species will readily feed on both birds and mammals, which is why it is the major vector of Western Equine Encephalitis and West Nile Virus (Belton, 2007; Wood et al., 1979). Both Western Equine Encephalitis and West Nile Virus are primarily diseases of wild birds, so when populations of both birds and Culex tarsalis are high, the risk of Western Equine Encephalitis and West Nile Virus increase and is likely to start showing up in mammal populations, especially in unvaccinated horses (Belton, 2002; Wood et al., 1979). This species is rated at high for vector competence in British Columbia (Belton, 2007). Culex tarsalis were found at all sites with very high numbers in the Waste Water Treatment Plant and McLure traps.

6.2.2. Culex pipiens This species is known as the “northern house mosquito” and will breed in almost type of water container, ditch, seepage or flooded field (Belton, 1983; Wood et al., 1970). It is often associated with pollution in the form of human or fecal waste (Wood et al., 1979). Adult females can overwinter in basements, rock slides and culverts. This species shows a strong preference for birds, although they will also bite mammals and reptiles (Belton, 2002; Wood et al., 1979). These mosquitoes are common in both urban and sub-urban settings and since they rarely fly more than 2-3 km from their larval development sites, when they are found, it can be assumed that they developed in a local larval development site (DeBess, 2003). This species has been known to transmit western equine encephalitis, St. Louis encephalitis and is a listed as a major vector of

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WNV in British Columbia with a competence rating of moderate in term of its ability to infect humans. However, it is the primary vector of WNV in birds and serves to amplify WNV in bird populations (Belton, 1983; 2002). Recent studies have shown that catch basins are significant larval development habitat for this species. Culex pipiens were found in five of the seven trapping locations (it was not found in the East Blackpool or Darfield traps), and was found in high numbers (>200 specimens) in the Kamloops Waste Water Treatment Plant trap.

6.3. CULISETA SPECIES The life-history of Culiseta mosquitoes is similar to that of Culex, with females laying their eggs directly on the surface of water (with the exception of Culiseta morsitans, which lays its egg rafts on vegetation at the margin of its larval development sites) (Belton, 1983). Females of most species lay multiple broods each year, and most overwinter as fertilized females. Five species of Culiseta mosquitoes were found in the TNRD this year.

6.3.1. Culiseta alaskaensis Culiseta alaskaensis is one of the largest mosquitoes in BC, with a wing length of five to seven millimeters (Belton, 1983). It is widely distributed throughout the Province, as well as throughout the boreal forests of northern Europe and Russia, but is generally found in low numbers (Belton, 1983; Wood et al. 1979). Females overwinter in sheltered locations, often under tree bark, and lay only one brood each year, even in warmer conditions (Belton, 1983). They tend to utilize small deep semi-permanent ponds with large amounts of emergent vegetation (Wood et al. 1979). While the females will bite humans in the shade, they are seldom significant pests (Belton, 1983). Belton (2004) does not include this species on his list of potential WNV vectors. One specimen was found in the Clearwater trap this year.

6.3.2. Culiseta incidens Culiseta incidens is a common species, and in 1932 was considered the commonest and most widespread species in the province (Belton, 1983). This was due to the fact that almost every rain barrel in the lower mainland was infested with larvae all summer long, which reflects this mosquito’s propensity for developing in artificial

BWP Consulting Inc Page 34 2011 Thompson-Nicola Regional District Mosquito Control Program containers and having multiple broods each year. They are also found in ditches and permanent and semi-permanent pools and are capable of tolerating polluted waters (Wood et al. 1979). They overwinter in rock slides and talus slopes and emerge early in the spring, and their large size coupled with their early appearance often causes strong reactions from people, even though they are not significant biters of humans. Females generally take blood meals from large mammals, but Belton (1983) has noted that they appear to feed more freely on humans during warm (> 20°C) evenings in the lower mainland. Belton (2007) gives this species a vector competence rating of low primarily because of its widespread distribution, although it has not been found to be infected with WNV. Culiseta incidens larvae have been found in ornamental ponds, children’s wading pools, garden center displays, catch basins and many other water holding containers in the TNRD. It was captured in low numbers in the Clearwater, Darfield, McLure, and Mission Flats traps.

6.3.3. Culiseta inornata Culiseta inornata was found in every trap in the TNRD this year except Darfield. It is a widespread mosquito, but since it prefers large mammals to man, it is seldom considered a pest. It breeds in deep woodland ponds, seepage ditches and polluted open water (Belton, 1983). This species overwinters as adults in mammal burrows and crevices, and emerges very early in the spring when it is still too cold for other species. These are the large mosquitoes often seen “hovering” close to people at dusk very early in the spring. Larvae have been found in ice-covered ponds (Wood et al., 1979). This wide-spread species is listed as a potential West Nile virus vector with a competence rating of “moderate” since it is willing to take blood meals from both mammals and birds (Belton, 2007). It was found in six of the seven trapping locations (it was not present in the Blackpool trap), and was found in high numbers at the McLure site.

6.3.4. Culiseta minnesotae This species is slowly migrating north from its typical range, and until recently has only been seen in the far southern portion of the province. In 2007 we observed this species in Salmon Arm, and this probably represents the near-northern extreme of its current range. It is one of the least-known mosquito species, but it is known that they

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overwinter as adults, and that there are probably more than one generation annually (Wood et al., 1979). Larvae are most often found concealed among dense clumps of vegetation, and feeding habits are similar to those of Culiseta morsitans (preferring birds but also feeding on small mammals and turtles). Belton (2007) does not include the species on his list, likely due to its minimal range in B.C., but it may be included in the future as its range expands due to the fact that it has multiple generations and feeds on birds. One specimen was found in Blackpool this year, the furthest north we have observed this species.

6.3.5. Culiseta morsitans In most of Canada, Culiseta morsitans overwinter as eggs, or possibly as larvae deep in silt or peat at the bottom of deep ponds (Belton, 1983). It has a fairly northern distribution, and has been found in a few widely scattered locations in BC (Belton, 1983). It is usually found in shaded conditions, associated with springs, sphagnum bogs and cedar swamps. They are almost exclusively bird feeders (Belton, 1983; Wood et al. 1979) and females captured in flight or reared from larvae would not take a blood meal (Belton, 1983). However, because they lay multiple batches of eggs each year (Wood et al. 1979) and feed on birds, Belton (2007) has given them a vector competence rating of ‘++’. One individual was captured in the Clearwater trap.

6.4. ANOPHELES SPECIES Anopheles species of mosquitoes are quite different in appearance than other mosquitoes, with narrow wings and long slender bodies. When standing, their hind ends are well elevated from their bodies, distinguishing them from other mosquito species. Because of these anatomical differences, they have been place in their own subfamily. Females overwinter as adults and hide in culverts, bridges, inside eaves and in the roofs of sheds (Belton, 1983). In urban areas, they hibernate in burrows, caves, hollow trees and other sheltered places (Belton, 1983). They prefer fresh, clean water and lay eggs singly among vegetation at the edges of water bodies. Anopheles species have been implicated in the transmission of malaria, and were no doubt involved in malarial outbreaks in Canada in the 19th century. All three of BC’s Anopheles species were found in the TNRD this year.

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6.4.1. Anopheles earlei Female Anopheles earlei overwinter in buildings, caves and mammal burrows, as well as hollow logs and tree trunks (Wood et al. 1979). When they overwinter, they are not blood-fed and have not laid eggs, but feed soon after leaving hibernation (Wood et al. 1979). In the southern part of the province, they are capable of two generations per year, weather permitting. The species is widely distributed throughout BC, and the females are vicious biters, able to attack in weather so cold that other mosquitoes are not capable of flying (Belton, 1983). Because of their ferocity, they can be localized pests when present in significant numbers. Belton (2007) gives this species a vector competence rating of “low”. It was found in low numbers in the McLure, Noble Creek and Mission Flats traps.

6.4.2. Anopheles freeborni Anopheles freeborni females overwinter in various sites including talus slopes, abandoned mines and buildings, and root cellars. They tend to breed in pools and sloughs formed by creeks, large marshes and irrigated pastures in Washington (Wood et al. 1979). In California, rice fields are a significant larval development site (Wood et al. 1979). They are capable of rearing in slightly saline water (salinity as much as 5%). This species is found in the arid areas of the province. It is potentially an effective vector of malaria and has been found naturally infected with Western Equine Encephalitis, but is never found in high enough concentrations to be important for disease transmission. Belton (2007) does not include this species on his list of vector competency. It was found in low numbers in the Noble Creek, McLure, and Mission Flats traps.

6.4.3. Anopheles punctipennis Anopheles punctipennis is the only anopheline found on Vancouver Island to date, and is fairly widespread throughout the province. Larvae are found in almost any kind of standing water (Belton, 1983), and there are generally two or three generations annually (Wood et al. 1979). Females bite humans freely after dark and are persistent in entering houses, but are not found in high enough concentrations to be a concern as a disease vector (Belton, 2983). Belton (2007) gives this species a vector competence rating of ‘+’. Three specimens were found in the McLure trap.

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7.0 MOSQUITO ADVISORY LINE

The TNRD has maintained an advisory telephone line for a number of years, which allows concerned residents to call a dedicated number and voice concerns about mosquito problems in their areas. This has proved to be a useful tool, as it often identifies problem areas and allows a reallocation of resources to these locales. In addition, it allows the field coordinator and technicians to contact people directly and educate them about such things as recognizing larval mosquitoes, eliminating larval development grounds, and organizing petitions for adulticiding. It also provides a means of evaluating the effectiveness of the mosquito control program in a given year, since the number of complaints received serves as a barometer of public opinion with regards to the severity of mosquito problems. When clients call the advisory line, they are greeted by an answering machine that allows clients to choose options which give recorded information about mosquito lifecycle, larval development sites, larviciding, adulticiding and current crew operations. It is expected that the recorded information answers some of our clients’ questions, thus reducing the number of messages left on the service. This year, there were approximately 34 individuals called the Advisory Line (some more than once). In June, there was a problem at the TNRD and substantial data was lost from the Mosquito Control Database. We were able to re-enter the mosquito control data as this is also on paper copy, however the Advisory Line calls are entered directly into the database and thus we were unable to recover the particulars of any calls prior to the data loss. This year, the majority of the calls were from the Blackpines area in the first week of July. Most landowners in the area wanted information regarding our larviciding schedule, although we also had two requests for adulticiding. One individual decided that she no longer wanted to be considered for adulticiding after she learned that the product used was malathion and the other did not meet the bite count thresholds for adulticiding. We also had calls from individuals in Rayleigh and Knutsford and we provided mosquito magnets for these individuals.

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There were no calls from Area ‘A’. This is likely due to the fact that landowners in this area have come to know our technician, Arvindeer Heer, very well over the past few years and will often contact him directly if they have any questions or concerns. Attempts were made to return all calls within 24 hours. and actions were taken as necessary. 8.0 THE KAMLOOPS SPRING AND FALL HOME AND GARDEN SHOWS &

TRAVELLING ROAD SHOW

BWP Consulting joined Martin Dickson and other TNRD contractors at both the Spring and the Fall Kamloops Home and Garden Shows. These have become annual events for the mosquito control team and provide opportunities for show casing the program, and for discussing mosquitoes, WNV and other issues with the public. Further, throughout the summer and fall of 2011, our mosquito control staff travelled with other employees and consultants for the TNRD on a Travelling Road Show with funding from the West Nile Virus Risk Reduction Initiative. They operated a booth and answered questions about the Nuisance and WNV mosquito control programs.

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9.0 WEST NILE VIRUS ACTIVITIES

This year funding was again provided by the Union of British Columbia Municipalities for the TNRD to conduct WNV related activities. These activities included public education, mosquito trapping, mosquito control, habitat reduction, and mapping. For specific details of these programs, refer to the 2011 Report of the TNRD WNV program.

10.0 RECOMMENDATIONS

1. Continue to larvicide as a primary means of controlling mosquito larvae in the Regional District. 2. Continue to utilize adulticiding only as a “last-resort” and when all conditions as described in the PMP are met. 3. Continue to use backpack blowers and helicopters to apply larvicide as these are the most economical means of dispersing larvicide (as opposed to “hand and bucket” treatment). 4. Continue to use methoprene in Cinnamon Ridge and Pritchard to control multiple generations of Culex and Ochlerotatus dorsalis larvae (this year Cinnamon Ridge was treated with methoprene under the WNV Initiative). 5. Continue to augment adult traps with dry ice as a means of increasing trap counts and species numbers.

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REFERENCES

Belton, P. (1983). The Mosquitoes of British Columbia. British Columbia Provincial Museum Publication: Handbook No. 41.

Belton, P. (2007). British Columbia Mosquitoes as Vectors of West Nile Virus. BCCDC website: www.bccdc.ca

DeBess, E. (2003). Mosquito control chemical guide: 2003 West Nile Virus response plan. Oregon Department of Human Services.

Wood, D.M., Dang, P.T., & Ellis, R.A. (1979). The Insects and Arachnids of Canada, Part 6: The Mosquitoes of Canada, Diptera: Culicidae. Ottawa, ON: Biosystematics Research Institute.

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