THOMPSON-NICOLA REGIONAL DISTRICT NUISANCE MOSQUITO CONTROL PROGRAM 2006 YEAR-END REPORT Prepared by: Burke Phippen, BSc., RPBio. Project Manager Cheryl Phippen, BSc., RN Field Coordinator DECEMBER 11, 2006 BWP CONSULTING INC.
TABLE OF CONTENTS TABLE OF CONTENTS... ii LIST OF FIGURES... iv LIST OF TABLES... v EXECUTIVE SUMMARY... 1 1.0 INTRODUCTION... 2 1.1. RESOURCES AVAILABLE FOR MOSQUITO CONTROL PROGRAM... 3 2.0 ENVIRONMENTAL FACTORS... 5 2.1. SNOW PACK... 7 2.2. FLOW LEVELS... 9 3.0 LARVICIDING PROGRAM... 10 3.1. HAND APPLICATION OF BTI LARVICIDE... 14 3.2. HELICOPTER APPLICATION OF LARVICIDE... 15 3.2.1. Snowmelt and Grassland Applications... 15 3.2.2. North and South Thompson Floodwater Applications... 15 3.3. LARVICIDE APPLICATION IN PRITCHARD... 18 3.4. PURCHASE OF LARVICIDE... 18 4.0 ADULTICIDING PROGRAM... 19 4.1. CALIBRATION OF ULV SPRAYERS... 19 4.2. APPLICATION OF ADULTICIDES... 19 5.0 DEVELOPMENT OF MOSQUITO CONTROL DATABASE... 20 6.0 LIGHT TRAPS... 21 6.1. ANALYSIS OF 2006 LIGHT TRAP CATCHES... 22 7.0 BIOLOGY OF MAJOR MOSQUITO SPECIES COLLECTED... 32 7.1. AEDINES IN GENERAL... 32 7.1.1. Aedes cinereus... 33 7.1.2. Aedes vexans... 33 7.1.3. Ochlerotatus canadensis... 34 7.1.4. Ochlerotatus fitchii... 34 7.1.5. Ochlerotatus increpitus... 35 7.1.6. Ochlerotatus intrudens... 35 BWP Consulting Inc Page ii
7.1.7. Ochlerotatus sticticus... 35 7.2. CULEX SPECIES... 35 7.2.1. Culex tarsalis... 36 7.2.2. Culex pipiens... 37 7.3. CULISETA SPECIES... 37 7.3.1. Culiseta inornata... 37 7.3.2. Culiseta incidens... 38 7.4. ANOPHELES SPECIES... 38 7.4.1. Anopheles earlei... 39 7.4.2. Anopheles freeborni... 39 8.0 RECOMMENDATION FOR THE LIGHT TRAPS... 39 9.0 MOSQUITO ADVISORY LINE... 40 10.0 THE KAMLOOPS SPRING HOME AND GARDEN SHOW... 41 11.0 WEST NILE VIRUS ACTIVITIES... 41 12.0 SUMMARY OF RECOMMENDATIONS... 41 13.0 ACKNOWLEDGEMENTS... 42 REFERENCES... 43 BWP Consulting Inc Page iii
LIST OF FIGURES Figure 1. Map outlining electoral boundaries and nuisance Mosquito Control Areas within the Thompson-Nicola Regional District... 4 Figure 2. Minimum and maximum daily temperatures ( C) measured at Blue River (graph by Ministry of Environment River Forecast Centre)... 6 Figure 3. Daily precipitation measured at Blue River (graph by Ministry of Environment River Forecast Centre).... 6 Figure 4. Snow pack at Kostal Lake, in the North Thompson watershed... 8 Figure 5. Snow pack at Park Mountain, in the South Thompson watershed... 8 Figure 6. 2006 water levels measured on the North Thompson River (WSC Hydrometric Station #08LB064) at McLure Ferry, BC (black line denotes normal water levels).. 9 Figure 7. Hydrograph of the North Thompson River at McLure showing dates of 2006 helicopter larviciding applications... 17 Figure 8. Hydrograph of the South Thompson River at Chase showing date of 2006 helicopter larviciding application.... 18 BWP Consulting Inc Page iv
LIST OF TABLES Table 1. Summary of maximum instantaneous discharge for the North Thompson River at McLure between 1998 and 2006... 10 Table 2. Historic amounts of granular larvicide (Bacillus thuringiensis var israeliensis) 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... 14 Table 5. Application of Bti Larvicides in Electoral Area A... 14 Table 6. Volumes of Malathion and Resmitherin used in the TNRD since 1989.... 20 Table 7. Numbers of adult mosquitoes captured each week in a New Jersey black-light trap at the Waste Water Treatment Plant in Kamloops, BC (dry ice baited)... 24 Table 8. Numbers of adult mosquitoes captured each week in a New Jersey light trap at the residence of Edward Babcock in Noble Creek, BC (dry ice baited)... 25 Table 9. Numbers of adult mosquitoes captured each week in a New Jersey light trap at McLure, BC (dry ice baited)... 26 Table 10. Mosquito specimens collected in the New Jersey Light Trap at Wetterstrom s in Darfield (baited with dry ice)... 27 Table 11. Numbers of adult mosquitoes captured each week in a New Jersey black-light trap set on Auldgirth Road in East Blackpool, BC.... 28 Table 12. Numbers of adult mosquitoes captured each week in a New Jersey black light trap near the Roundtop Road Wildlife Sanctuary in Blackpool, BC.... 29 Table 13. Numbers of adult mosquitoes captured each week in a New Jersey black-light trap at the residence of Chris Fleury on Archibald Rd in Clearwater, B.C.... 30 Table 14. Number of mosquitoes trapped in each of the New Jersey Light Traps... 31 Table 15. Historic numbers of mosquitoes trapped per night in Areas J, L, O and P, and Area A. Trapping sites vary over the years.... 32 BWP Consulting Inc Page v
EXECUTIVE SUMMARY Environmental conditions, including high precipitation and warm temperatures in mid- May, combined to create a rapid snowmelt and the highest water levels in the North Thompson River since 1999. A total of 12,625.06 kg of Bti larvicide was applied to 1262.42 ha as part of the nuisance control program this summer. Of this, 1487.11 kg of Vectobac and 497.15 kg of Aquabac was applied by hand, and 10,134 kg of Vectobac and 506.8 kg of Aquabac was applied by helicopter. No adulticiding was performed in 2006. 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 early September, and each was sampled on a weekly basis to estimate population sizes and determine species distribution. A total of 4133 mosquitoes and 25 different mosquito species were trapped and identified during this time. This resulted in an average of 11.2 mosquitoes per night in Area A, and 3.7 mosquitoes per night in the remaining areas. Aedes and Ochlerotatus spp. represented 74% of the catch, Culex spp. 17%, Culiseta spp. 5.6%, Anopheles spp. 2.8%, and Coquillettidia perturbans made up the remaining less than 1% of the catch. Approximately 31 telephone calls were fielded by the Mosquito Advisory Line this summer. The majority of the calls were from landowners requesting larviciding in known sites. Other individuals called to report new larval development sites, to report high adult mosquito populations and to ask questions about West Nile virus. 2006 marks the eighth year that BWP Consulting Inc. has conduct the mosquito control program in the TNRD, and marks the second year of a 5-year contract. We have again included a few recommendations for improvements in the program and we look forward to next year s mosquito season. BWP Consulting Inc Page 1
1.0 INTRODUCTION The Thompson-Nicola Regional District (TNRD) began its formal mosquito control program approximately 30 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 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, Chase and Logan Lake 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 part-time project coordinator and a full-time field coordinator between April 1 and September 30. In addition, four full-time technicians are funded for the time period of April 15 through ust 15. The contract also includes up to 30 hours of helicopter flight time, one day of jet boat use, a few days of ATV use, and mileage for all vehicles 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 to Vavenby on 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. These areas are monitored by three full-time technicians. A forth technician is employed as a floater and spends time helping the other technicians as needed. BWP Consulting Inc Page 2
1.1. RESOURCES AVAILABLE FOR MOSQUITO CONTROL PROGRAM The TNRD owns and maintains a Hudson larvicide applicator, two Leco 500 Ultra-Low Volume (ULV) adulticiding units and a droplet analyzer for calibrating these machines, seven New Jersey light traps, one gravid trap, a number of black-light CDC mosquito traps, one portable Solo backpack ULV sprayer, one London Fog portable aerosol generator, seven 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 resmitherin (adulticides). BWP Consulting Inc Page 3
Figure 1. Map outlining electoral boundaries and nuisance Mosquito Control Areas within the Thompson-Nicola Regional District. BWP Consulting Inc Page 4
2.0 ENVIRONMENTAL FACTORS 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 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 is the predominant factor affecting both snow-melt pools and rates and heights of river floods. In 2006, the snow-pack levels in both the North and South Thompson drainages were below normal to near-normal early in the season, but a sudden temperature increase in mid- May (Figure 2), coupled with precipitation levels 65% higher than normal in May (Figure 3) resulted in a quick melt and a reduction in snowpack to below-normal levels (see Figure 4 and Figure 5). BWP Consulting Inc Page 5
36 34 32 Normal Max, Min 30 28 26 24 22 20 Temperature Deg C 18 16 14 12 10 8 6 4 2 0-2 -4-6 -8 01-Apr 06-Apr 11-Apr 16-Apr 21-Apr 26-Apr 01-May 06-May 11-May 16-May 21-May 26-May 31-May 05-Jun 10-Jun 15-Jun 20-Jun 25-Jun 30-Jun 05-10- Date Figure 2. Minimum and maximum daily temperatures ( C) measured at Blue River (graph by Ministry of Environment River Forecast Centre). 120 100 Cumulative Normal Precipitation 80 Precip - mm 60 40 20 0 01-Apr 06-Apr 11-Apr 16-Apr 21-Apr 26-Apr 01-May 06-May 11-May 16-May 21-May 26-May 31-May 05-Jun 10-Jun 15-Jun 20-Jun 25-Jun 30-Jun 05-10- Date Figure 3. Daily precipitation measured at Blue River (graph by Ministry of Environment River Forecast Centre). BWP Consulting Inc Page 6
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 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 4 (North Thompson) and Figure 5 (South Thompson). Snow pack at Kostal Lake ranged between 57% and 94% of normal between January and June, while levels at Park Mountain ranged between 55% and 98% of normal water equivalents. Snow pack was near average in both watersheds in the early part of the year, but decreased rapidly to below-average levels in early May. BWP Consulting Inc Page 7
1600 Snow water equivalent (mm of water) 1400 1200 1000 800 600 1999 2004 2005 2006 Maximum Normal 400 200 0 Jan Feb Mar Month Apr May Jun Figure 4. Snow pack at Kostal Lake, in the North Thompson watershed 1600 1400 1200 1999 2004 2005 2006 Maximum Normal Snow water equivalent (mm of water) 1000 800 600 400 200 0 Jan Feb Mar Month Apr May Jun Figure 5. Snow pack at Park Mountain, in the South Thompson watershed. BWP Consulting Inc Page 8
2.2. FLOW LEVELS Flow levels in the North Thompson climbed rapidly in mid-may to well above normal levels, then gradually decreased to near or below average levels for the reminder of the freshet period (Figure 6). Table 1 shows the maximum discharge for the North Thompson River at McLure between 1998 and 2006. Here, we can see that flows in 2006 were higher than those measured in the previous six years, with only those occurring in 1999 (the year of the big flood) exceeding them. Higher discharge levels result in increased areas of flooding and therefore increased larval development habitat. 3000 2500 2000 Normal Flow 2-year Return Period Flow 1972 Flow 1974 Flow Previous Peaks 2006 Flow m3/s 1500 1000 500 0 01-Apr 03-Apr 05-Apr 07-Apr 09-Apr 11-Apr 13-Apr 15-Apr 17-Apr 19-Apr 21-Apr 23-Apr 25-Apr 27-Apr 29-Apr 01-May 03-May 05-May 07-May 09-May 11-May 13-May 15-May 17-May 19-May 21-May 23-May 25-May 27-May 29-May 31-May 02-Jun 04-Jun 06-Jun 08-Jun 10-Jun 12-Jun 14-Jun 16-Jun 18-Jun 20-Jun 22-Jun 24-Jun 26-Jun 28-Jun 30-Jun 02-04- 06-08- 10- Date Figure 6. 2006 water levels measured on the North Thompson River (WSC Hydrometric Station #08LB064) at McLure Ferry, BC (black line denotes normal water levels) BWP Consulting Inc Page 9
Table 1. Summary of maximum instantaneous discharge for the North Thompson River at McLure between 1998 and 2006. Year Maximum instantaneous discharge (m 3 /s) Date upon which maximum discharge occurred 1998 1570 May 29 1999 2590 Jun 21 2000 1630 Jun 10 2001 1620 May 30 2002 1920 Jun 18 2003 1530 Jun 11 2004 1290 Jun 07 2005 1870 May 17 2006 2067 May 25 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 resmitherin are wide-spectrum insecticides, with the ability to kill beneficial insects as well as pests, and can also be toxic to vertebrates including fish, birds and mammals. Aquabac (PCP 26863, active ingredient (a.i.) 2.86%) and Vectobac (PCP 18158, a.i. 2.80%) are trade names of the two biological mosquito larvicides used in the TNRD nuisance mosquito control program. The active ingredient of these products is the bacterium Bacillus thuringiensis var israeliensis (Bti) which formulated as a granule with crushed corncob as a carrier. The product is effective against mosquitoes and other members of the order Diptera in the larval stage, and is applied by hand, backpack blower or by helicopter to standing water containing significant populations of mosquito larvae. Application rates vary from 3 to 20 kilograms per hectare (with the higher rates applied to polluted or highly organic water), although in 2006, most sites were treated at a rate of 10 kilograms per hectare. BWP Consulting Inc Page 10
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 2006, Altosid was used to target larvae in two chronically over-irrigated fields: one west of the Pritchard subdivision and one at Cinnamon Ridge. All applications of this product were conducted under the West Nile Virus Risk Reduction Initiative in 2006, and are discussed further in the Final Report of the TNRD 2006 West Nile Virus Risk Reduction Program. At the request of the Ministry of Environment, areas containing fish or contiguous with fish habitat are ineligible for nuisance control treatments, since the larvicide could potentially affect fish productivity by eliminating a food source (mosquito larvae). Therefore, only areas that are separate from the river and that do not support fish populations are suitable for larviciding. This year a total of 12,625.06 kg of Bti larvicide was applied to 1262.42 ha of larval development area (1003.95 kg of Aquabac over 100.39 ha and 11,621.11 kg of Vectobac over 1162.03 ha). Table 2 shows the historic application of granular larvicide. The amounts of Bti larvicide used and the corresponding areas treated in 2006 are shown in Table 3, Table 4, and Table 5. This spring, many snowmelt sites that contained no water for the last couple of years were full of water and had high concentrations of larvae. Many of the snow melt pools were producing 200-400 larvae per dip this year, while in recent years we have been seeing less than 40 larvae per dip. Predictably, snowmelt areas such as Lac Le BWP Consulting Inc Page 11
Jeune, Pinantan, Knutsford, Rose Hill, Logan Lake and Pritchard were treated earlier in the year, from early April to mid-may, as snow-melt pools formed. For the first time, a large flooded area from an early freshet of Mann Creek in Blackpool was also treated in April by helicopter. This treatment was in response to a number of complaints received last spring in early-may. In late-may, the highest peak of the North Thompson occurred and large quantities of larvicide were applied to larval development areas along this river in the last few days of May and the beginning of June. As the snow-melt and freshet pools slowly dried up in late-june, y and ust, treatments predictably decreased. Table 2. Historic amounts of granular larvicide (Bacillus thuringiensis var israeliensis) used in the TNRD. Year Granular Larvicide (kg) 1989 3161.00 1990 5561.00 1991 3470.00 1992* 1998.80 1993 2675.50 1994 4198.95 1995 3717.63 1996 7147.21 1997 8356.00 1998 3972.94 1999 9243.90 2000 9480.70 2001 7171.4 2002 12,589.31 2003 13,030.52 2004 9721.5 2005 10,201.41 2006 12,625.06 *First year Electoral A entered the program BWP Consulting Inc Page 12
Area Table 3. Application of Bti Larvicides in Mosquito Area South (Kamloops, Chase, Logan Lake, Areas J, L, & part of P. April 1- April 30 May 1- May 31 June 1-June 30 y 1- Sept 1 Total Larvicide (kg) Area (ha) Larvicide (kg) Area (ha) Larvicide (kg) Area (ha) Larvicide (kg) Area (ha) Larvicide (kg) Aberdeen/Sahali 13 1.3 13 1.3 Chase 1.0 0.1 168.6 16.86 169.6 16.96 Cherry Creek 0.1 0.01 5.0 0.5 5.1 0.51 Barnhartvale 12.0 1.2 8 0.8 20 2 Heffley Creek 16.2 1.62 8.05 0.805 24.25 2.425 Knutsford 768.2 76.82 768.2 76.82 Lac du Bois 46 4.6 46 4.6 Lac La Jeune 24.1 2.41 24.1 2.41 Community Lac La Jeune 259.2 25.92 259.2 25.92 Logan Lake 405.84 40.58 405.84 40.58 Monte Creek 26 2.6 26 2.6 Noble Creek 144.8 14.48 150.7 15.07 15 1.5 310.5 31.05 North Thompson 162.9 16.29 162.9 16.29 Paul Lake 618.9 61.89 618.9 61.89 Pinantan Lake 677.7 67.75 4.0 0.4 681.7 68.15 Pritchard 77.55 7.755 10 1 70.3 7.03 157.85 15.78 Rayleigh 133.5 13.35 133.5 13.35 Rose Hill 22.85 2.285 22.85 2.285 Sun Peaks 41.3 4.13 1.0 0.1 470.6 47.06 512.9 51.29 Thompson 54.3 5.43 54.3 5.43 Vinsulla 127.7 12.77 184.8 18.48 312.5 31.25 Totals 2540.9 254.07 752.44 75.24 1415.85 141.5 20 2 4729.19 472.8 Area (ha) BWP Consulting Inc Page 13
Area Table 4. Application of Bti Larvicides in Mosquito Area North (Area O and part of P ). April 1- April 30 May 1- May 31 June 1-June 30 y 1-31 Total Larvicide (kg) Area (ha) Larvicide (kg) Area (ha) Larvicide (kg) Area (ha) Larvicide (kg) Area (ha) Larvicide (kg) Barriere 600 60 15 1.5 615 61.5 Blackpines 452.5 45.25 108.6 10.86 561.1 56.11 Chinook Cove 126.7 12.67 126.7 12.67 Simpcw FN 289.6 28.96 22.5 2.25 312.1 31.21 Darfield 18 1.8 1252.4 125.24 131 13.1 1401.4 140.14 Little Fort 760.2 76.02 1.5 0.15 761.7 76.17 McLure 366 36.54 8 0.8 374 37.34 Totals 18 1.8 3847.4 384.68 264.1 26.41 22.5 2.25 4152 415.14 Area (ha) Area Table 5. Application of Bti Larvicides in Electoral Area A April 1- April 30 May 1- May 31 June 1-June 30 y 1- Sept 1 Total Larvicide (kg) Area (ha) Larvicide (kg) Area (ha) Larvicide (kg) Area (ha) Larvicide (kg) Area (ha) Larvicide (kg) Birch Island 479.9 47.99 60 6.0 24.95 2.495 564.85 56.485 Blackpool 713 71.3 1407.72 140.772 52.6 5.26 13.6 1.36 2186.92 218.692 Clearwater 307.7 30.77 7.25 0.725 0.85 0.085 315.8 31.58 East Blackpool 586.7 58.67 52.85 5.285 6 0.6 645.55 64.555 Upper Clearwater 6.75 0.675 21 2.1 1.0 0.1 28.75 2.875 Vavenby 2 0.2 2.0 0.2 Total 713 71.3 2788.77 278.877 195.7 19.57 46.4 4.64 3743.87 374.387 Area (ha) 3.1. HAND APPLICATION OF BTI LARVICIDE Hand application of Aquabac was initiated in early April, and continued until mid-ust. A total of 108.3 kg of Vectobac and 116.0 kg of Aquabac was applied by hand and backpack blower to 10.83 ha and 11.60 ha respectively 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 many of these were treated by hand as well. BWP Consulting Inc Page 14
In Mosquito Area South, hand treatments included 942.39 kg of Vectobac applied to 94.23 ha and 320.7 kg of Aquabac applied to 32.07 ha. The most heavily hand treated areas in Mosquito Area South were Pritchard, Pinantan, Knutsford and Logan Lake. Finally, in Electoral Area A, 436.42 kg of Vectobac were applied by hand to 43.642 ha of larval development area and 60.45 kg of Aquabac were applied by hand to 6.045 ha of larval development area. This is the first time that all staff have had access to backpack applicators and it has made in incredible improvement to the speed and ease of hand applications. These units have also cut down on the amount of larvicide used as there is less wastage with a more even application over the larval development sites. 3.2. HELICOPTER APPLICATION OF LARVICIDE Our company employed Kevin Jackson of Cariboo Helicopters to perform all helicopter surveillance and larviciding work this summer. 3.2.1. Snowmelt and Grassland Applications The first helicopter campaign was on April 22 nd and 1945.7 kg of Vectobac was used to treat 194.56 ha of snowmelt pools in Pinantan, Paul Lake, Scadam Flats, Lac Le Jeune and Knutsford. A total of 5.8 hours of flight time were utilized. The second helicopter application took place in the Blackpool area on April 26 th. Last year, in early May, we received a number of complaints concern adult mosquitoes in the area. This year we sent staff to assess the area early in the season and found that a large area of Mann Creek had flooded and many larvae were developing. It was decided that helicopter application would be our most effective means of control due to limited accessibility to this large, deep site. On April 26 th, 713 kg of Vectobac was applied and 2.7 hours of flight time was utilized. 3.2.2. North and South Thompson Floodwater Applications The highest peak of the North Thompson River occurred on approximately May 25 th at 4.5m (2067 m 3 /sec) (Figure 7). Many of our sites begin to activate when the river level reaches close to 3.0 m which occurred on about May 15 th. The flooded habitat was extensive (this was the second highest peak in the last nine years) and since it took a full 10 days from site activation to river peak, we were anxious for the levels to subside so we BWP Consulting Inc Page 15
could initiate a helicopter campaign. On May 29 th the river seemed to plateau at about 3.5m (still very high with incredibly large areas of habitat) (Figure 7). It was felt that we could not wait any longer and we initiated a large scale helicopter campaign on May 30 th that took three days to complete. On May 30 th, 7.1 hours of helicopter time was used to apply 2,534 kg of Vectobac to 253.4ha of habitat with nuisance larvae within Area A (Birch Island, Clearwater, Blackpool and East Blackpool) and 289.6 kg of Vectobac to 28.96ha of active habitat in the Little Fort area. The following day, May 31 st, 7.3 hours of helicopter time was used to apply 3,801 kg of Vectobac to standing water along the North Thompson between Little Fort and Blackpines (including Little Fort, Darfield, Chinook Cove, Simpcw First Nation, Barriere, McLure, Vinsulla, Noble Creek and Blackpines). On this day, it became apparent that due to the extensive area of habitat that was being treated, we were going to run out of larvicide. Therefore, two staff members were sent to Langley on the evening of May 30 th to pick up 80 bags of Aquabac 200G from Morrow BioSciences. At 7 am on June 1 st the staff received the product and drove back to Kamloops to join the rest of the crew who were busy conducting the third day of our helicopter applications. On June 1 st larviciding activity began with further applications in Blackpines, Noble Creek, and Rayleigh along the North Thompson followed by applications near Cinnamon Ridge and the Kamloops Waste Water Treatment Plant. A total of 724 kg of Vectobac was applied to 72.4 ha in these areas. The South Thompson River began to climb and activate sites in Kamloops, Pritchard and Chase on May 19 th and appeared to hit a plateau around May 26 th (Figure 8). By the end of May, the river was showing no signs of subsiding and we were starting to see 3 rd and 4 th instar larvae so we made the decision to treat with helicopter on June 1 st. On this date, 36.2 kg of Aquabac and 18.1 kg of Vectobac was applied to 3.62 ha and 1.81 ha of habitat near Pritchard. A further 108.6 kg of Vectobac was applied to 10.86 ha of larval development habitat near Chase. Unfortunately, the South Thompson continued to rise slowly and hand treatments of the area continue through June and y. BWP Consulting Inc Page 16
Following treatment in Chase, the helicopter flew directly to Sun Peaks and applied 470.6 kg of Aquabac to 47.06 ha of active larval habitat. In all, the helicopter flew for a total of 7.1 hours on June 1 st. 2500 2000 Helicopter campaign (North Thompson, Barriere to Noble Creek (WNv funding)) 1500 Flow (m 3 /s) 1000 500 Helicopter campaign (snowmelt) Helicopter campaign (Blackpool) Helicopter campaign (North and South Thompson, Sunpeaks) Helicopter campaign (City of Kamloops (WNv funding)) 0 1-Apr-06 8-Apr-06 15-Apr-06 22-Apr-06 29-Apr-06 6-May-06 13-May-06 20-May-06 27-May-06 3-Jun-06 10-Jun-06 17-Jun-06 24-Jun-06 1--06 8--06 Date Figure 7. Hydrograph of the North Thompson River at McLure showing dates of 2006 helicopter larviciding applications. BWP Consulting Inc Page 17
Figure 8. Hydrograph of the South Thompson River at Chase showing date of 2006 helicopter larviciding application. 3.3. LARVICIDE APPLICATION IN PRITCHARD In the summer of 2004, a petition was circulated expressing concerns over nuisance mosquitoes in Pritchard, BC. Last year, investigations in the area resulted in the discovery of a number of previously unknown larval rearing sites. The most significant is a large area in a farmer s field directly west of the subdivision. This area is flooded intermittently throughout the summer as a result of over-irrigation and new batches of larvae are produced each time the flooding occurs. For the last two years, this site has been pre-treated with Altosid under the WNv funding and has been retreated every 30-40 days. There has not been a complaint from this subdivision for the last two summers. 3.4. PURCHASE OF LARVICIDE For a number of years, it has been recommended that the TNRD purchase their entire budget of larvicide prior to the start of the mosquito season, rather than in small batches throughout the summer. This has worked very well, and larvicide has been on hand whenever it has been needed. It is recommended that this practice continue. Also, the success seen with the application of Altosid in Pritchard has been remarkable. It is recommended that Altosid be purchased annually for the nuisance control program. BWP Consulting Inc Page 18
4.0 ADULTICIDING PROGRAM The TNRD Mosquito Adulticiding Program is facilitated by the use of two truckmounted Leco 500 Ultra-Low Volume (ULV) sprayers and one portable Solo backpack ULV sprayer. Both malathion and resmitherin 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 resmitherin, 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 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 resmitherin 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 animals. Instructions are given to landowners prior to a spray campaign to keep windows and doors shut, turn airconditioners and fans off, and keep pets in the house or under cover, if at all possible. 4.1. CALIBRATION OF ULV SPRAYERS There was no need for calibration of the sprayers this year. 4.2. APPLICATION OF ADULTICIDES There was only one request for adulticiding this year, and that was from a landowner in the Darfield area on Friday June 30th. Our staff was scheduled to visit her place following the long weekend on Tuesday afternoon. Over the weekend, a heat wave hit the area, and by Tuesday, the adults were nearly gone and the landowner agreed that adulticiding was no longer necessary. This is the fifth time that BWP Consulting has met BWP Consulting Inc Page 19
the goal of a spray-free season. Historical amounts of adulticide applied in the TNRD can be found in Table 6. Table 6. Volumes of Malathion and Resmitherin used in the TNRD since 1989. Year Malathion (L) Resmitherin (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 5.0 DEVELOPMENT OF MOSQUITO CONTROL DATABASE During the winter and spring of 2006, a company (IdeaLever Ltd) was hired to make modifications to the TNRD mosquito database. There were changes made to the way that data can be summarized and the way that the database handles West Nile virus versus nuisance control larval treatments. The database is now operational and our staff all agree that the changes have been great! BWP Consulting Inc Page 20
6.0 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 1- octen-3-ol (a chemical attractant). 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 9-13 weeks this year using some funding from the 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 Chris Fleury on Archibald Street; (2) Blackpool, next to the Blackpool Wildlife Sanctuary; (3) East Blackpool at the residence of Mr. Grenier; (4) Darfield at MacColl Rd; (5) McLure at the residence of Bob Hearn; (6) Noble Creek at the residence of Edward Babcock and Linda Wrightson, and (7) at the Waste Water Treatment Plant. There were two changes to the trap sites this year. The Clearwater trap was previously located at the Clearwater Improvement District Office, but since it was stolen from this location last summer, a more secure location was chosen. The second change was in Blackpool as the trap was moved from the Mulligan s residence north of the Roundtop Wildlife Sanctuary to the residence of Rosy Marks just south of the Sanctuary. This change was made as a gate to the Mulligan s property was often locked and guarded by a Doberman Pincher. Once a week, the traps at Darfield, McLure, Noble Creek and the Waste Water Treatment Plant were augmented with dry ice in beverage coolers. Dry ice is a powerful mosquito attractant as it sublimates to carbon dioxide and mimics animal and bird breath. All of the light traps were set during the first week of June this summer. Insects collected in the traps were dried or frozen and 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. BWP Consulting Inc Page 21
6.1. ANALYSIS OF 2006 LIGHT TRAP CATCHES This year, trap counts were in line with what was expected given the high peak of the North Thompson and the extensive larval development habitat that remained into late summer (Table 7to Table 14). Average nightly trap counts were up from last year s numbers in all trapping location except East Blackpool. As usual, the East Blackpool trap produced the greatest numbers of mosquitoes (Table 11) (a total of 1979 specimens and approximately half of the total trap count for all seven traps). This trap captured 23.6 mosquitoes per trapping night which is significantly fewer than last years average of 39.7 mosquitoes per night. This reduction in the number of adults (even with an increase in larval habitat) can be attributed to increased helicopter application in the area and diligent hand treatments throughout the summer. The average trap count per night for Area A was 11.2 mosquitoes per night (Table 15). This is slightly lower than last year, however it is still quite high compared to trap counts seen in the last few years. The extensive flooding of the North Thompson River in 2006 is responsible for these high counts. The vast majority of the mosquitoes collected in Area A were floodwater species of the genera Ochlerotatus and Aedes (94% 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 (2170 specimens of Aedes vexans were captured with 1497 of these from East Blackpool). The second most prevalent species in Area A was the nuisance mosquito Ochlerotatus sticticus which comprised 10% of the total traps counts with 283 specimens. In the traps located in Mosquito Area North and Mosquito Area South, the average nightly catch was 3.7 mosquitoes, up from last years nightly count of 1.6 mosquitoes per night (Table 15). This year the southern trap sites captured high numbers of Culex tarsalis and Culex pipiens mosquitoes. Populations of these mosquitoes exploded throughout the hot areas of the province this summer as water was left standing from the spring freshet well into summer, when these sites are usually dried up by late June or early y. These mosquito species can be a problem as vector species, however as they prefer to bite birds, they are rarely considered a pest of humans. It is important to note that the numbers of nuisance floodwater species captured in the southern trapping BWP Consulting Inc Page 22
locations were low as a reflection of timely larval control immediately following the peak of the North Thompson. A total of 25 species were identified from all six genera present in British Columbia (Table 14). As usual, the most abundant species captured this year was BC s most important nuisance mosquito, Aedes vexans, which made up 60% of the total catch of 4133 mosquitoes (Table 14). When all 14 of the Aedes and Ochlerotatus (floodwater) species counts were tallied, they comprised approximately 74% of the total catch (3057 specimens). Culex mosquitoes made up 17% of the total catch (716 specimens). This composition is considerably higher than last year (last year Culex comprised 7% of the total catch) and there were nearly three times more Culex mosquitoes captured in total (716 total specimens, up from 256 specimens last year). Culiseta mosquitoes made up 5.6% of the total catch (231 specimens), Coquillettidia perturbans comprised less than 1% of the total catch (12 specimens) and Anopheles species made up 2.8% of the total catch (117 specimens) (Table 14). The WNv vector species Culex tarsalis was present in all trapping locations and was particularly abundant at the Noble Creek, Waste Water Treatment Plant, Darfield and McLure locations (Table 14). Culex pipiens, another important WNv vector, was present in very high numbers in the Waste Water Treatment Plant trap. These mosquitoes appeared in the traps in early-y through ust and would not normally have been captured since surveillance for nuisance mosquitoes is generally concluded by this time of the year. BWP Consulting Inc Page 23
Table 7. Numbers of adult mosquitoes captured each week in a New Jersey blacklight trap at the Waste Water Treatment Plant in Kamloops, BC (dry ice baited). Date (2006) Species Jun 12 Jun 19 Jun 26 05 10 18 27 08 14 21 29 Sep 12 Total Anopheles freeborni 1 1 Culex pipiens 1 2 7 3 5 13 39 10 12 69 113 274 Culex tarsalis 3 5 11 13 10 28 5 1 1 11 88 Culiseta inornata 1 2 3 3 3 12 Ochlerotatus communis 2 2 Ochlerotatus dorsalis 1 1 Ochlerotatus implicatus 1 1 Ochlerotatus Male* 2 1 3 Total Number Captured 0 4 8 25 16 20 42 47 10 13 73 124 382 Total Males Captured 0 2 2 12 6 7 13 35 7 8 50 82 224 *Male Ochlerotatus can be difficult to identify BWP Consulting Inc Page 24
Table 8. Numbers of adult mosquitoes captured each week in a New Jersey light trap at the residence of Edward Babcock in Noble Creek, BC (dry ice baited). Date (2006) Species Jun 13 Jun 26 05 10 18 25 27 04 08 21 29 Sep 12 Total Aedes vexans 19 13 42 34 5 1 7 6 5 1 1 134 Anopheles earlei 2 5 1 1 9 Anopheles freeborni 1 1 2 4 4 14 27 53 Anopheles punctipennis 2 2 Culex pipiens 3 1 2 6 Culex tarsalis 2 4 18 86 52 11 4 9 4 1 9 200 Culiseta incidens 5 1 1 2 9 Culiseta impatiens 1 1 Culiseta inornata 2 6 11 23 20 9 2 13 4 3 2 95 Culiseta morsitans 1 1 Ochlerotatus canadensis 1 1 Ochlerotatus fitchii 1 1 Ochlerotatus increpitus 1 1 1 3 Ochlerotatus mercurator 1 1 Ochlerotatus Male* 2 3 1 6 Total Number Captured 31 28 74 145 80 1 30 17 36 14 23 43 522 Total Males Captured 9 11 45 34 9 0 5 6 11 6 7 25 168 *Male Ochlerotatus can be difficult to identify BWP Consulting Inc Page 25
Table 9. Numbers of adult mosquitoes captured each week in a New Jersey light trap at McLure, BC (dry ice baited). Date (2006) Species * 16 28 03 15 21 22 30 Sep 13 Total Aedes vexans 29 2 5 36 Aedes cinereus 1 1 Anopheles earlei 2 1 1 1 1 1 7 Anopheles freeborni 3 3 Culex pipiens 1 1 Culex tarsalis 15 2 4 7 5 14 1 48 Culiseta inornata 1 1 Ochlerotatus intrudens 12 12 Ochlerotatus pullatus 1 1 Ochlerotatus sticticus 12 12 Total Number Captured 70 5 5 10 6 23 1 2 122 Total Males Captured 0 3 3 7 4 13 0 1 31 *y 16 th was the first date that a suitable sample was obtained. The trap was set June 7 th, but problems with the light burning out and the power source resulted in no samples until mid-y. BWP Consulting Inc Page 26
Table 10. Mosquito specimens collected in the New Jersey Light Trap at Wetterstrom s in Darfield (baited with dry ice). Date (2006) Species Jun 14 Jun 26 04 12 16 18 28 03 04 15 21 22 Sep 13 Total Aedes vexans 12 12 23 1 31 53 2 2 136 Aedes cinereus 1 2 3 Anopheles earlei 2 3 1 6 Coquillettidia perturbans 6 6 Culex tarsalis 2 1 5 17 16 4 5 1 51 Culiseta alaskaensis 1 1 Culiseta incidens 1 1 1 3 Culiseta inornata 2 3 3 3 7 1 19 Ochlerotatus intrudens 17 1 18 Ochlerotatus mercurator 1 1 Ochlerotatus sticticus 4 5 5 26 40 Ochlerotatus Male* 1 1 Total Number Captured 20 39 39 1 85 0 79 2 10 0 0 8 2 285 Total Males Captured 8 3 5 0 9 0 15 0 2 0 0 1 1 44 *Male Ochlerotatus can be difficult to identify BWP Consulting Inc Page 27
Table 11. Numbers of adult mosquitoes captured each week in a New Jersey blacklight trap set on Auldgirth Road in East Blackpool, BC. Date (2006) Species Jun 14 Jun 21 Jun 28 05 12 19 26 02 09 16 23 30 Total Aedes vexans 224 136 190 244 314 92 190 94 7 4 1 1 1497 Aedes cinereus 26 50 31 26 3 2 5 143 Anopheles earlei 3 1 1 5 Anopheles freeborni 1 1 Coquillettidia perturbans 4 4 Culex tarsalis 3 2 1 6 Culiseta alaskaensis 2 2 Culiseta inornata 2 2 13 4 1 5 2 29 Ochlerotatus fitchii 6 6 Ochlerotatus intrudens 9 4 13 Ochlerotatus provocans 3 3 Ochlerotatus pullatus 3 3 Ochlerotatus sticticus 30 72 64 43 33 12 8 4 1 267 Total Number Captured 284 260 285 329 363 114 219 107 9 4 1 4 1979 Total Males Captured 85 56 67 46 15 3 8 3 1 0 0 2 286 BWP Consulting Inc Page 28
Table 12. Numbers of adult mosquitoes captured each week in a New Jersey black light trap near the Roundtop Road Wildlife Sanctuary in Blackpool, BC. Species Jun 15 Jun 22 Jun 29 06 13 20 Date (2006) 27 03 10 17 24 31 Total Aedes vexans 31 10 81 92 64 26 295 55 7 2 1 664 Aedes cinereus 3 2 5 1 11 Anopheles earlei 1 1 3 1 4 10 2 22 Anopheles freeborni 3 3 Anopheles punctipennis 3 3 Culex tarsalis 1 3 1 1 6 Culiseta inornata 2 2 1 1 3 9 Ochlerotatus fitchii 1 1 2 Ochlerotatus intrudens 1 1 Ochlerotatus sticticus 2 1 4 5 4 16 Total Number Captured 37 12 93 108 72 33 314 58 7 2 0 1 737 Total Males Captured 24 0 38 22 17 5 6 3 0 0 0 0 115 BWP Consulting Inc Page 29
Table 13. Numbers of adult mosquitoes captured each week in a New Jersey blacklight trap at the residence of Chris Fleury on Archibald Rd in Clearwater, B.C. Date (2006) Species Jun 14 Jun 21 Jun 28 05 12 19 26 02 09 16 23 30 Total Aedes vexans 2 2 1 1 1 1 1 9 Aedes cinereus 1 1 Anopheles earlei 1 1 Anopheles freeborni 1 1 Coquillettidia perturbans 2 2 Culex pipiens 1 4 4 8 5 4 1 2 1 30 Culex tarsalis 2 2 2 6 Culiseta incidens 3 2 1 1 4 2 4 6 3 2 28 Culiseta impatiens 3 3 6 Culiseta inornata 1 1 5 2 2 1 2 1 15 Ochlerotatus canadensis 1 3 4 Ochlerotatus fitchii 1 1 Ochlerotatus intrudens 1 1 Ochlerotatus punctor 1 1 Total Number Captured 5 2 8 14 13 9 20 10 15 4 5 1 106 Total Males Captured 2 1 1 2 4 3 5 6 5 0 0 0 29 BWP Consulting Inc Page 30
Table 14. Number of mosquitoes trapped in each of the New Jersey Light Traps. Waste Water Treatment Plant Noble Creek McLure Darfield East Blackpool Blackpool Clearwater Total Species Aedes cinereus 1 3 143 11 1 159 Aedes vexans* 134 36 136 1497 664 9 2476 Anopheles earlei* 9 7 6 5 22 1 50 Anopheles freeborni 1 53 3 1 3 1 62 Anopheles punctipennis 2 3 5 Coquillettidia perturbans * 6 4 2 12 Culex pipiens * 274 6 1 30 311 Culex tarsalis * 88 200 48 51 6 6 6 405 Culiseta alaskaensis 1 2 3 Culiseta impatiens 1 6 7 Culiseta incidens 9 1 3 28 41 Culiseta inornata * 12 95 19 29 9 15 179 Culiseta morsitans* 1 1 Ochlerotatus canadensis 1 4 5 Ochlerotatus communis 2 2 Ochlerotatus dorsalis* 1 1 Ochlerotatus fitchii 1 6 2 1 10 Ochlerotatus implicatus 1 1 Ochlerotatus increpitus 3 3 Ochlerotatus intrudens 12 18 13 1 1 45 Ochlerotatus mercurator 1 1 2 Ochlerotatus provocans 3 3 Ochlerotatus punctor 1 1 Ochlerotatus pullatus 1 3 4 Ochlerotatus sticticus* 12 40 267 16 335 Ochlerotatus male 3 6 1 10 Totals 382 522 122 285 1979 737 106 4133 No. trap nights 97 97 65 98 84 85 84 610 Ave. catch / night 3.9 5.4 1.9 2.9 23.6 8.7 1.3 6.8 * Mosquito species present on Peter Belton s list of British Columbia Mosquitoes as Vectors of West Nile Virus. BWP Consulting Inc Page 31
Table 15. Historic numbers of mosquitoes trapped per night in Areas J, L, O and P, and Area A. Trapping sites vary over the years. Year Areas J, L, O and P Area A 1989 3.4 1990 8.12 1991 2.02 1992* 0.18 1993 10.21 73.07 1994 1.24 5.40 1995 5.41 6.33 1996 7.31 13.11 1997 2.47 18.00 1998 0.31 3.13 1999 3.31 7.36 2000 0.03 0.59 2001 0.32 0.07 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 *First year Electoral A entered the program 7.0 BIOLOGY OF MAJOR MOSQUITO SPECIES COLLECTED 7.1. AEDINES IN GENERAL Until recently, all of the floodwater (i.e., laying their eggs on moist soil rather than on the waters 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 BWP Consulting Inc Page 32
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 fourteen different species of Aedes and Ochlerotatus species were trapped and they composed about 74% of the individuals caught in the TNRD light traps. The major Aedine species captured this year in the TNRD was Aedes vexans (Table 14), although large numbers of Ochlerotatus sticticus were also captured in East Blackpool. 7.1.1. 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 fly 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 does not appear on Belton s (2002) list of potential West Nile Virus vectors. This year, Aedes cinereus were present in all trapping locations in Area A as well as in the Darfield trap. 7.1.2. 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, BWP Consulting Inc Page 33
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 (2002) 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 except at the Kamloops Waste Water Treatment Plant, and was the most significant species in the East Blackpool, Darfield and Blackpool traps. The total number of specimens from all traps this year was 2476 (Table 14) with the majority being from East Blackpool (1497 specimens). 7.1.3. Ochlerotatus canadensis Ochlerotatus canadensis eggs usually hatch in temporary woodland pools as early as the beginning of April, although some eggs seem to have a delayed hatching mechanism as they have been observed hatching throughout the summer as late as ust (Woods et al., 1979). Belton (1983) reports that this species in usually not considered a pest in BC due to its low numbers. However, it can be a persistent biter in the forest and tends to bite on the lower legs. This species is rated + as a WNv vector (Belton, 2004) since specimens of this species have tested positive for the virus in other areas of North America. 7.1.4. 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. BWP Consulting Inc Page 34
7.1.5. 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 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 (2002) does not include this species on his list of potential WNv vectors. 7.1.6. Ochlerotatus intrudens This tiny mosquito, although short lived, can be a troublesome biter (Woods et al., 1979). It is common throughout Canada, but rarely abundant. Larvae of this species develop in temporary woodland pools and are often found associated with Ochlerotatus communis. This species is not expected to be a transmitter of WNv. 7.1.7. 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, 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). 7.2. 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). BWP Consulting Inc Page 35
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 encephalites 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 transmit the virus to her next host. 7.2.1. 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, 2002; 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, 2002). Culex tarsalis were found in all seven trapping locations with quite large numbers in the McLure, Darfield, Noble Creek and the Kamloops Waste Water Treatment plant traps. BWP Consulting Inc Page 36
7.2.2. 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 animal 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 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 all trapping locations except Darfield, Blackpool and East Blackpool, and were the major mosquito species captured in the Kamloops Waste Water Treatment Plant trap. 7.3. 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. 7.3.1. 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 BWP Consulting Inc Page 37
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, 2002). 7.3.2. 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 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 (2002) 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 this summer. 7.4. 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 BWP Consulting Inc Page 38
implicated in the transmission of malaria, and were no doubt involved in malarial outbreaks in Canada in the 19 th century. 7.4.1. 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 (2002) gives this species a vector competence rating of low. These mosquitoes were present in all trapping locations except at the Kamloops Waste Water Treatment Plant. 7.4.2. 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 (2002) does not include this species on his list of vector competency. 8.0 RECOMMENDATION FOR THE LIGHT TRAPS It is recommended that light trapping continue in the same locations as this year. It is also recommended that the TNRD continue using dry ice when it is feasible. BWP Consulting Inc Page 39
9.0 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, 31 calls were received on the Advisory Line. Ten calls were requests for our company to continue larviciding activities in previously mapped development sites. In these cases, home owners just wanted to make sure we were planning to visit. Six calls were received from individuals that were new to the program and wanted us to assess standing water on their properties. Each of these landowners were visited and new sites were mapped on five of the caller s residences (the sixth caller was located near Barriere Lake and was considered outside of the treatment area). Six calls were received from landowners that were concerned about adult mosquito populations. Each of these calls was from a different location with one call from each from the Noble Creek, Rayleigh, Westsyde, McLure, Darfield and East Blackpool areas. Six calls were received from individuals that had concerns regarding West Nile virus. Some of these callers were reporting standing water on neighbouring properties and others just wanted information on the illness. The final call was from an individual who was upset that we do not conduct routine adulticiding any longer and she was upset at the number of spiders on her property. All calls were returned within 24 hours and actions were taken as necessary. BWP Consulting Inc Page 40
10.0 THE KAMLOOPS SPRING HOME AND GARDEN SHOW The Spring Home and Garden show was March 10 th -12 th this year, and was busier than it has been in the last couple of years. Information about the TNRD nuisance control program, as well as information about WNv was displayed at our booth. We also provided brochures produced by the TNRD and the Interior Health Authority and displayed live mosquito larvae (although it was a challenge to find larvae this early in the season). 11.0 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 2006 Report of the TNRD WNv program that was provided to the TNRD earlier this fall. 12.0 SUMMARY OF RECOMMENDATIONS Throughout this report we have made recommendations that may facilitate the effective delivery of this program in future years. We will summarize each of these here, with a reference to the section where they originated so that the reader can view them in context. Section 3.4. : 1) It is recommended that the TNRD continue to purchase as much larvicide as possible at the beginning of the year, and store larvicide that does not fit into the TRND storage sheds at a secure rented storage locker. 2) We recommend that methoprene pellets be used to treat the flood-irrigated areas next to the community of Pritchard and other similar sites. Altosid should be purchased annually as part of the nuisance control program. Section 8.0 : 1) It is recommended that the TNRD continue using dry ice to augment the adult mosquito traps when it is feasible. BWP Consulting Inc Page 41
13.0 ACKNOWLEDGEMENTS As always, we have many people to thank. This year was a challenge due to the increased workload associated with the second highest water levels in the last eight years. This made the work both challenging and stressful as the goal of zero adulticiding weighs heavy on everyone s mind. We cannot thank enough our exceptional manager, Neil Horvath, and his crew of Bob Davis, Shaun Roberts, Ron Lampreau, Heather McNeil, Leslie Bradwell, April Hamilton, and Jodi Teranishi. We are so thankful that each of you was willing to take on this program (and the WNv program) this year and put in the long, hard hours that you did. We praise each of you for your dedication to the environment and your strong beliefs in providing an effective larviciding campaign. This was our second summer utilizing the services of Cariboo Helicopters and Kevin Jackson. Kevin was enthusiastic, flexible and a great deal of fun to work with. Thank you again for your hard work, Kevin. And finally, thanks again to all the TNRD staff that listened to my concerns and gave us the resources to conduct this program. BWP Consulting Inc Page 42
REFERENCES Belton, P. (1983). The Mosquitoes of British Columbia. British Columbia Provincial Museum Publication: Handbook No. 41. Belton, P. Personal communications and presentation at the West Nile Virus Planning Meeting November 28 th, 2002 at the British Columbia Center for Disease Control in Vancouver, B.C. Belton, P. (2002) British Columbia Mosquitoes as Vectors of West Nile Virus. BCCDC website: www.bccdc.org 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. BWP Consulting Inc Page 43