Metro Vancouver Final Report Nuisance Mosquito Control Program 2017

Transcription

1 Metro Vancouver Final Report Nuisance Mosquito Control Program 2017 December

2 By: Michael Jackson PhD and Kate Patterson BSc Kingsway Avenue Burnaby, B.C. V5H 1Y9 Phone: Fax:

3 Executive Summary Culex Environmental has been responsible for implementing the Nuisance Mosquito Control Program since 2006 for select Metro Vancouver Regional Parks and five Metro Vancouver municipalities: District of Maple Ridge, City of Pitt Meadows, City of Surrey, the Township of Langley and the City of Coquitlam (which was added to the program in 2012). The Nuisance Mosquito Control Program includes: (i) regular monitoring of larval mosquito populations on municipal land (and on certain private lands in the Township of Langley), (ii) treatment with the bacterial larvicides Bti and BSph when numbers of larvae exceed threshold levels, (iii) biweekly monitoring of adult populations at two sites in each of the five municipalities, and (iv) public outreach. In 2017, monitoring of the Surrey Salt Marsh began in the second week of April, while regular weekly monitoring of all sites began on May 1 st. Due to the unusually high seasonal rainfall and resultant higher river level into early July, regular weekly monitoring continued later than in previous years, until the middle of July, when monitoring frequency was reduced to biweekly until the end of August. Of the 5,093 site visits in 2017, 83 contained mosquito larvae resulting in a total count of 3,134, down from 11,927 last year. In 2017, the unusually cold weather in May and early June delayed the hatching of larvae and only a very small number of mosquitoes collected in the majority of samples. The most common species overall was Aedes dorsalis. By late June, when temperatures were warm enough to hatch out larvae, the Salt Marshes had mostly dried up and the largest numbers of mosquitoes were Aedes sticticus and Aedes vexans, emerging from the floodplains in the Township of Langley and Maple Ridge. There were also a significant number of Mansonia perturbans adults identified in 2017, however, the overall number was much lower than previous years. In 2017 the river rose to its highest level, 5.6 meters, on June 4 th. Two aerial treatments were conducted, the first between June 9 th and 12 th and a second application on June 29 th. Between May 1 st and August 8 th, 2.80 kg of VectoBac 200G and 17.0 kg of Vectolex CG were applied by hand in the Metro Vancouver nuisance control program including Northwest Langley WWTP and cattail treatments. In 2016, Culex implemented a strategic treatment plan targeting cattails for the very aggressive nuisance mosquito Mansonia perturbans. The program was continued in 2017 and adult trapping at cattail treatment areas showed a reduction in numbers from 2015 and 2016, indicating that over time the treatments may be reducing the established population of Mansonia in these areas. In 2017 Culex Environmental attended five community events (one in each municipality) to help residents understand the behaviour and biology of mosquitoes, as well as how they can best eliminate mosquito breeding grounds on their properties. The Mosquito Hotline (plus s from participating municipality coordinators) enabled residents of the municipalities to make enquiries and voice concerns regarding nuisance mosquitoes in their vicinity. Between the Hotline and municipal coordinator s, 110 concerns were recorded, compared to 28 in 2016, 23 in 2015, and 95 in 2014, which was a wet year comparable to We recommend on-going monitoring of adult populations and all surface water sites for larvae in 2018 that have been previously identified as productive nuisance sites on public lands, Park lands within in the scope of the program, and private lands in the Township of Langley. We also recommend continuing the early treatment of cattail habitat, in all municipalities where cattail habitat has been identified, with Bacillus sphaericus to control Mansonia perturbans. 3

4 Table of Contents Executive Summary Introduction Historical Nuisance Program Mansonia perturbans Treatment Strategy Methodology Site Surveys Surface Waters Adult Mosquito Trapping Sampling Techniques Surface Water Larval Mosquito Sampling Adult Mosquito Trapping Sample Processing Mosquito Larvae Adult Mosquitoes Larvicide Treatment Data Management Results Surface Water Larval Mosquito Sampling Adult Mosquito Monitoring Larvicide Treatment Nuisance Mosquito Hotline Public Education and Communications Discussion and Recommendations Mansonia perturbans Climatic Factors Program Effectiveness and Recommendations Long-Term Program Effectiveness West Nile Virus Update References Appendices

5 List of Figures Figure 1: Metro Vancouver Nuisance Mosquito Control Larvicide Applications ( )... 9 Figure 2: Number of Concern Calls Each Year ( )... 9 Figure 3: Number of Concern Calls Each Year Compared to Peak River Level of Fraser River at Mission Gauge ( ) Figure 4: Number of Larval Samples and Number of Samples Containing Mosquitoes Taken by Culex Environmental ( ) Figure 5: Adult Species Distribution ( ) Figure 6: Sample Pesticide Treatment Form Figure 7: Surface Water Sampling Form Figure 8: Numbers of Aedes species in Adult Traps Figure 9: Aerial Treatment of Brae Island June 9 th and June 12 th Figure 10: Aerial Treatment of Brae Island June 29 th Figure 11: Average number of Mansonia perturbans in adult traps in 2013 to Figure 12: Metro Vancouver River Level, Temperature, Precipitation and Snowpack Figure 13: Metro Vancouver River Level, Temperature, Precipitation and Snowpack Figure 14: Metro Vancouver River Level, Temperature, Precipitation and Snowpack Figure 15: Metro Vancouver River Level, Temperature, Precipitation and Snowpack Figure 16: Metro Vancouver River Level, Temperature, Precipitation and Snowpack Figure 17: Metro Vancouver River Level, Temperature, Precipitation and Snowpack Figure 18: Average Number of Larvae Before and After Treatment Figure 19: Average Number of Larvae found Before and After Treatment across all Four Municipalities

6 List of Tables Table 1: Samples Collected in May Table 2: Samples Collected in June Table 3: Samples Collected in July Table 4: Samples Collected in August Table 5: Samples Collected at GVR Table 6: Metro Vancouver Nuisance Adult Trapping Results Table 7: Results of Adult Trapping near Cattail Treatment Sites in the Township of Langley Table 8: VectoBac Treatments in Maple Ridge Table 9: VectoBac Treatments in Surrey Table 10: VectoBac Treatments in the Township of Langley Table 11: VectoBac Treatments of Metro Vancouver Parks Table 12: Vectolex Treatments of Cattails for Mansonia perturbans Table 13: Concern Calls Summary Table 14: Total Number of human, mosquito, bird and horse cases of West Nile virus in British Columbia since Table 15: Total number of human cases and fatalities due to West Nile virus since introduction in New York in

7 1.0 Introduction 1.1 Historical Nuisance Program Metro Vancouver has been running a nuisance mosquito abatement program since This program has included: (i) regular monitoring of larval populations on municipal land, (private land in the Township of Langley, upon owner s request), (ii) larvicide treatment, when necessary, with the bacterial agent Bacillus thuringiensis israelensis (Bti) and Bacillus sphaericus (BSph) when threshold numbers of larvae are exceeded, (iii) biweekly monitoring of adult populations at two sites in each municipality, and (iv) public education and outreach, including operation of a Nuisance Mosquito Hotline to enable residents to make enquiries and voice concerns regarding nuisance mosquitoes in their neighborhoods. Nuisance mosquito species in the Lower Mainland are typically aggressive daytime biters such as Aedes vexans, Aedes dorsalis and Aedes sticticus. These species tend to develop in areas subject to intermittent flooding, such as riparian margins and seepage areas in the Lower Fraser floodplain. The larvae of these species are rarely found in permanent water bodies, particularly those that hold healthy natural predator populations. However, another aggressive nuisance species, Mansonia perturbans has now established populations in the Lower Mainland. Mansonia perturbans is increasingly becoming a source of the nuisance problem, even in particularly dry years such as 2015, due to the habitat of the larvae being mostly cattail beds that are not regulated by intermittent flooding, but are rather more permanent. A cattail treatment plan targeting Mansonia perturbans was implemented in In 2016 and 2017 there was a decrease in the emergence of Mansonia perturbans adults, thus indicating that the established populations may be decreasing in number in response to the treatments. Early in the history of the Nuisance Program, larvicide treatment encompassed large open water areas often over 500 hectares in size (Figure 1). However, the corresponding numbers of concern calls that arose in the vicinity of these areas suggest that the wide scale treatments were not very effective at eliminating the source of the problem in many areas (Figures 2-3). The number of site visits in each year of the program has varied, based on conditions, duration and changes in the scope, but generally has increased with each year of the program (Figure 4). There is now a long-term trend showing an overall reduction in the proportion of samples containing mosquitoes following year-on-year implementation of the fully integrated IMMPACT control program. In 2007 there was an extensive emergence of nuisance mosquitoes in the Township of Langley (Jackson et al. 2007). The problem arose from the appearance of a previously rare species, Aedes sticticus, which had been known to develop in its aquatic stages in seepage pools amongst cottonwood stands, but neither larvae nor adults of this species had been found in any numbers for many years (Hearle 1926, Jackson et al. 2007). The resurgence of Aedes sticticus appears to have happened synchronously across southern BC. In 2008, Culex Environmental identified new areas of potential breeding habitat to be included in monitoring programs through a survey of the Township of Langley s foreshore, including McMillan Island (Jackson et al. 2008a). The 2008 freshet rose rapidly, resulting in a large area requiring treatment on McMillan Island (Jackson et al. 2008b). In 2009, an extended spring freshet resulted in the need for two aerial treatments with new cohorts of larvae hatching as rising water levels increasingly inundated new areas. These treatments resulted in a significant reduction in mosquito populations as well as concern calls (Jackson et al 2009). 7

8 In 2010 the Brae Slough Enhancement program resulted in Coho and Chinook salmon colonizing the main channel preventing treatment under the Integrated Pest Management Act and Regulation (BC Ministry of Environment 2006). In this year the spring freshet was comparatively low and only reached the 4.0m mark at the Mission gauge. Aerial treatment occurred twice on MacMillan Island and numbers of concern calls on the mosquito hotline remained low (Jackson et al. 2010) At the start-up meeting for the 2011 program it was decided that the Surrey saltwater sites would be monitored every week beginning in April as the mosquitoes at this location did not respond to the bi-weekly treatments that took place in It was also decided that these sites would be treated with the bacterial pesticide Vectolex CG as it is a longer lasting pesticide and works better in salt water than Vectobac 200G. In 2012, the freshet was very high in amplitude, causing the river level to rise to over 6m at the Mission Gauge. Areas were flooded that had not been flooded in over 10 years, inundating eggs that were laid many years ago that were still viable. This led to an increase in the proportion of samples which contained mosquitoes (18% in 2012 versus 11% in 2011). In 2013, the freshet occurred relatively early in the season, and occurred in synchrony with a high level of precipitation. These two factors combined to create an increased amount of standing water, particularly on Brae Island, where the aerial treatment was carried out (Jackson et al. 2013). Despite the increased water, treatment was remarkably effective, resulting in a very low number of concern calls throughout the season. The 2014 season had a moderately high freshet that, combined with some rain events occurring after aerial treatments must have caused a secondary hatch of nuisance mosquitoes, resulting in higher levels of both Aedes sticticus and Aedes vexans adults, and subsequent higher numbers of concern calls (95). The large increase in adult populations, however, was from Mansonia perturbans. Over 4,000 of the 7,500 adult mosquitoes trapped were identified as this vicious biter (Jackson and McMahon 2014). The 2015 season was extremely dry, with snow pack levels far below the long term average. Fewer site visits were required due to dry conditions, and an exceptionally low number of concern calls were received. No aerial treatment was required on Brae Island, saving thousands of dollars in larvicide and helicopter costs (Jackson and McMahon 2015). The 2016 season was extremely warm early on, with snow pack melt occurring earlier in the season, thus causing the river level to remain low, below the point at which there is enough water to cause hatching of floodplain mosquitoes. No aerial treatment was required on Brae Island, even though there was considerably more precipitation than in The 2017 season was extremely cold early on, with very few mosquitoes collected in samples until mid-june. However, warming temperatures coincided with the rising river level in mid-june resulting in a large emergence of adults from the floodplains at MacMillan Island and Kanaka Creek. This led to a higher number of concern calls (110) than in the last two years, most of which came from the Fort Langley area near Brae Island. Two aerial treatments helped to abate the large emergence of adults from Brae Island in June. 8

9 Figure 1: Metro Vancouver Nuisance Mosquito Control Larvicide Applications ( ) Figure 2: Number of Concern Calls Each Year ( ) 9

10 Figure 3: Number of Concern Calls Each Year Compared to Peak River Level of Fraser River at Mission Gauge ( ) Figure 4: Number of Larval Samples and Number of Samples Containing Mosquitoes Taken by Culex Environmental ( ) 10

11 1.2 Mansonia perturbans Treatment Strategy 2017 Between 2011 and 2016 Mansonia perturbans has been the dominant adult species collected in adult traps (Figure 5). In 2015 a very large number of Mansonia were caught, which was not expected to happen in such a dry season was a much wetter year than 2015 and also produced a large number of Mansonia. As per recommendations for 2017 (Jackson and Patterson, 2016), this year, Culex continued treating cattail sites with Bacillus sphaericus in all municipalities where cattail sites had been identified in The number of Mansonia caught in adult traps in 2017 was much lower than previous years, while Aedes species numbers were the highest in Figure 5: Adult Species Distribution ( ) 11

12 2.0 Methodology 2.1 Site Surveys Surface Waters In total, 461 different surface water sites were sampled for larvae across the five jurisdictions, Metro Vancouver Parks, and Northwest Langley WWTP. 27 new sites were added in 2017, no sites were removed. Township of Langley: 226 sites (Appendix A) City of Surrey: 75 sites (Appendix B) District of Maple Ridge: 49 sites (Appendix C) City of Pitt Meadows: 34 sites (Appendix D) City of Coquitlam: 32 sites (Appendix E) Select Metro Vancouver Regional Parks (Kanaka Creek, Derby Reach, and Brae Island): 69 sites (included in TOL and MR site maps, list below) Northwest Langley WWTP: 10 sites (Appendix F) (draining and earth-filling lagoons) Kanaka Creek Brae Island Derby Reach MR-155 BRAE-2 TOL-261 TOL-1075 TOL-358 MR-156 BRAE-3 TOL-262 TOL-1076 TOL-359 MR-158 TOL-1070 TOL-263 TOL-334 TOL-360 MR-159 TOL-1071 TOL-264 TOL-335 TOL-361 MR-160 TOL-1072 TOL-265 TOL-336 TOL-362 MR-161 TOL-1073 TOL-266 TOL-337 TOL-363 MR-32 TOL-1074 TOL-311 TOL-338 TOL-364 MR-97 TOL-232 TOL-700 TOL-339 TOL-365 MR-559 TOL-233 TOL-701 TOL-350 TOL-366 TOL-238 TOL-702 TOL-351 TOL-367 TOL-239 TOL-703 TOL-352 TOL-601 TOL-240 TOL-704 TOL-353 TOL-602 TOL-256 TOL-705 TOL-354 TOL-603 TOL-260 TOL-706 TOL-355 TOL-604 TOL-356 TOL-605 TOL-357 TOL

13 Date Created Site Name Source 08-Jun-17 MA-22 Mansonia Sampling 08-Jun-17 MA-23 Mansonia Sampling 08-Jun-17 MA-24 Mansonia Sampling 08-Jun-17 MA-25 Mansonia Sampling 30-Jun-17 MR-103 Hotline 30-Jun-17 MR-108 Hotline 07-Jul MR-130 Hotline 29-May-17 SR-111 Hotline 12-May-17 SR-145 Coordinator 12-May-17 SR-146 Coordinator 12-May-17 SR-148 Coordinator 28-Jun-17 TOL-002 Hotline 28-Jun-17 TOL-003 Hotline 28-Jun-17 TOL-1010 Hotline 28-Jun-17 TOL-1011 Hotline 26-May-17 TOL-1014 Hotline 26-May-17 TOL-1015 Hotline 26-May-17 TOL-1016 Hotline 26-May-17 TOL-1017 Hotline 28-Jun-17 TOL-1018 Hotline 28-Jun-17 TOL-1019 Hotline 09-Jun-17 TOL-403 Hotline 09-Jun-17 TOL-404 Hotline 09-Jun-17 TOL-405 Hotline 06-Jun-17 TOL-707 Hotline 26-May-17 TOL-998 Hotline 26-May-17 TOL-999 Hotline Adult Mosquito Trapping Surrey, Langley, Maple Ridge, Coquitlam and Pitt Meadows were each allocated two adult mosquito light trap site locations. Adult trapping locations remained the same as in 2016 in all municipalities. Adult mosquitoes were sampled eight times from these ten trapping sites at 14-day intervals between May 8 th and August 18 th, for a total of 80 trap nights. 2.2 Sampling Techniques Surface Water Larval Mosquito Sampling 13

14 At each surface water site, larvae and pupae were sampled using a standard 350mL long handled dip sampler. The standard larval sampling procedure described in the Municipal Mosquito Control Guidelines (Silver 2008) was followed. Larvae were collected from each of ten dips at each surface water site Adult Mosquito Trapping At each adult mosquito monitoring site, mosquitoes were sampled using a Centre for Disease Control (CDC) light trap which was baited with dry ice, set out between 3:00 pm and 7:00 pm and picked up the next morning between 8:00 am and 10:00 am. 2.3 Sample Processing Mosquito Larvae The number of larvae (early and late instars) and pupae sampled were recorded cumulatively. Depending upon the number of specimens, the samples were placed in either small clear plastic vials or in Ziploc bags, which were then placed in a cooler for transport. For identification purposes, specimens were counted and categorized as either early (1st or 2nd) or late (3rd and 4th) instars. Late instars were preserved for identification in 70% ethanol. Earlier instars were kept in large containers and reared to later instars which were subsequently preserved for identification. Similarly, pupae were kept in containers and reared to adults. The newly emerged adults were placed in a freezer overnight and then dried before identification. All larvae and pupae collected were identified to the lowest possible taxonomic level Adult Mosquitoes Adult mosquitoes collected in the CDC traps were transported to the Culex laboratory, where they were frozen, then identified. Identifications were conducted using a dissecting microscope and a taxonomic key from Wood et al. (1979). All individuals were identified to the lowest possible taxonomic level. 2.4 Larvicide Treatment The larvicide generally used for this program is VectoBac which contains the biological agent, Bacillus thuringiensis israelensis (Bti), the most widely used control agent in the fight against mosquito nuisance. Used throughout North America in all the areas infected with WNv, it offers the fastest response while doing minimal harm to the environment. Bti has been researched for many years and is one of the most stringently researched pesticides in North America. The bacterial cells of Bti produce a spore and a crystalline protein toxin, or endotoxin, as they develop. When the mosquito larvae ingest the spores, the protein toxin is activated by alkaline conditions and enzyme activity in the 14

15 larval gut. The activated toxin attaches to specific receptor sites resulting in paralysis and destruction of the cells in the gut wall. Larvae usually die quickly from the activity of the toxin or may stop feeding and die within two or three days from the effect of septicaemia (blood poisoning). Bti bacteria do not persist in the environment in sufficient quantities to provide continuing control of target pests. A treatment threshold of ten or more late instar larvae in any five 350ml dips of a ten dip sample was used to determine when larvicide should be applied. An application rate of 1.0g of product per square meter of wetted area was targeted specifically at 3 rd and 4 th instar larvae. If ten or more late instar larvae were collected, the Bti treatment was conducted. When the larvae found exceeded threshold numbers but they were earlier instars, treatment was deferred until they reached later stages. VectoBac 200G was either applied by hand or backpack blower. Vectolex CG, containing a different bacterium as an active agent called Bacillus sphaericus was also applied by hand in certain salt marsh sites and cattail sites, as described above. Records of each larvicide treatment were taken to log the application rate, the area, product name, name of the applicator, and license number. Reports of all larvicide applications were electronically sent to the program administrator (Figure 6). Figure 6: Sample Pesticide Treatment Form 15

16 2.5 Data Management At the end of each sampling day, field technicians connect to Wi-Fi at Culex laboratory and submit their larval sampling forms, and pesticide treatment forms, if any (Figure 7). The forms are immediately stored in the cloud, and accessible by the Operations Manager. Pesticide forms are downloaded and transmitted to the Metro Vancouver coordinator. The larval sampling data is downloaded, checked for errors, corrected, and then uploaded to the IMMP database stored in the cloud. Larval identifications are submitted when completed on a separate form and also uploaded to the IMMP database after verification. Figure 7: Surface Water Sampling Form 16

17 3.0 Results 3.1 Surface Water Larval Mosquito Sampling Of the 5,093 site visits in 2017, 83 site visits resulted in larvae being collected (Tables 1 through 5). A total of 3,134 larvae were collected and 2,531 larvae were identified. This is down from 11,927 larvae collected in 2016 and 29,395 larvae collected in The most commonly identified species was Aedes dorsalis, with 818 larvae identified, comprising 32% of the total. Nuisance mosquitoes, Aedes vexans and Aedes sticticus were at 16.3% up from 2.2% identified in Potential high risk West Nile virus vectors (Culex tarsalis and Culex pipiens) accounted for 12.7% of identified larvae, down from 24% in The sewage lagoons were monitored for mosquito larvae weekly from the beginning of May to the end of June, when the pools were emptied of water and thus no more sampling was required. A total of 17 (down from 1,406) larvae were collected and 2 larvae were identified (Table 5). Culex tarsalis was the only species identified. Tables 1 through 5: Larval Species Identification in all Municipalities and Parks in Table 1: Samples Collected in May Culex SiteID Date Total Mosquitoes Collected Total Mosquitoes Identified Non Mosquito Larvae Unknown Mosquito Aedes aloponotum Aedes dorsalis SR /18/ SR /18/ SR /18/ SR /26/ SR /26/ SR /01/ SR /01/ SR /01/ SR /09/ SR /09/ SR /15/ SR /15/ MR /18/ SR /23/ TOL /31/ N/A N/A N/A N/A N/A BRAE-2 05/31/ N/A N/A N/A N/A N/A Total Note: No samples collected in Coquitlam and Pitt Meadows in May. 17

18 Table 2: Samples Collected in June Date Culex Site ID Total Collected Total Identified Unknown Mosquito 05/31/2017 BRAE /31/2017 TOL /01/2017 MR /05/2017 SR /05/2017 SR /05/2017 TOL /05/2017 SR /05/2017 SR /06/2017 TOL /07/2017 TOL /07/2017 TOL /07/2017 TOL /07/2017 TOL /07/2017 TOL /08/2017 MR /08/2017 COQ /09/2017 TOL /12/2017 SR /09/2017 TOL /19/2017 SR /14/2017 TOL /14/2017 TOL /14/2017 BRAE /15/2017 MR /16/2017 TOL /16/2017 TOL /16/2017 TOL /16/2017 TOL /19/2017 TOL /21/2017 TOL /23/2017 TOL /23/2017 TOL /23/2017 TOL /23/2017 TOL /26/2017 TOL /28/2017 TOL /30/2017 TOL /30/2017 TOL /30/2017 TOL /30/2017 MR /30/2017 TOL Total Note: No samples collected in Pitt Meadows in June. Aedes aloponotum Aedes dorsalis Aedes japonicus Aedes sticticus Aedes vexans Anopheles punctipennis Culex pipiens Culex tarsalis Culex territans Culiseta incidens Culiseta inornata 18

19 Table 3: Samples Collected in July Date Culex Site ID Total Larvae Collected Total Larvae Identified Unknown Mosquito 07/04/2017 SR /04/2017 SR /04/2017 TOL /07/2017 TOL /07/2017 TOL /13/2017 MR /14/2017 TOL /14/2017 TOL /14/2017 TOL /17/2017 TOL /18/2017 TOL /18/2017 TOL /18/2017 TOL /19/2017 TOL /20/2017 GVR /20/2017 GVR /20/2017 GVR /25/2017 SR Total Note: No samples collected in Coquitlam and Pitt Meadows in July. Aedes dorsalis Aedes japonicus Anopheles punctipennis Culex pipiens Culex tarsalis Culex territans Culiseta incidens Culiseta inornata Table 4: Samples Collected in August Date Culex Site ID Total Larvae Collected Total Larvae Identified Unknown Mosquito 08/01/2017 TOL /01/2017 TOL Total Note: No samples collected in Coquitlam, Pitt Meadows, Maple Ridge and Surrey in August. Culex pipiens Culiseta incidens 19

20 Table 5: Samples Collected at GVR Culex SiteID Date Total Mosquitoes Collected Total Mosquitoes Identified Non Mosquito Larvae Culex tarsalis GVR998 05/15/ GVR /19/ GVR /26/ GVR998 05/26/ GVR986 06/23/ Total KEY FINDINGS FROM LARVAL MOSQUITO SURVEILLANCE Of the 5,093 site visits in 2017, 83 sites contained mosquito larvae. A total of 3,134 larvae were collected. Culex tarsalis and Culex pipiens, both high risk West Nile virus vectors, made up 12.7% of the larval collection (322). Aedes dorsalis, the species found predominantly at the Surrey Salt Marsh, made up 32%, up 11% from Adult Mosquito Monitoring Adult mosquitoes were trapped biweekly at two locations in each of the five municipalities. Eight trapping rounds were conducted between May 8 th and August 18 th From the samples collected over 80 trap nights, 4,017 (down from 6,668 in 2016) adult mosquitoes were identified (Table 6). Aedes sticticus was the most commonly collected mosquito. In 2015 and 2016, the Fraser River did not flood and very few Aedes species emerged. Since 2013, Mansonia perturbans has been the dominant species collected in adult traps, up to 88% of identified adults in 2016, 73% in 2015 and 54% in was the first year since 2012 where a unique combination of temperature and flood conditions led to a high emergence of Aedes species from the floodplain, thus causing higher numbers of those species to be collected in adult traps. In 2017, Mansonia accounted for just 15% of all adult species collected, while Aedes sticticus accounted for 57%. Typically, Mansonia perturbans adults are mostly captured in the adult traps in June. In 2016 and 2015, the majority 20

21 of the Mansonia perturbans adults were collected in June. In 2017, the emergence of Mansonia began later than in previous years, with the highest numbers being trapped at the end of June and into the beginning of July. The later emergence in 2017 was likely due to the unseasonably cold temperatures in May and June In addition to the biweekly adult trapping, as part of a new treatment program to address the growing concerns over Mansonia perturbans becoming established in the Lower Mainland, 16 additional adult traps were set in the Township of Langley at four different locations between June 16 th and July 26 th, near cattails that were being treated biweekly with Vectolex CG. As shown in Table 7, Mansonia perturbans adults were consistently trapped at all four sites throughout the Township of Langley, which are shown in Appendix G. Adult trapping for Mansonia began later than in 2016 due to the cold weather conditions throughout May and early June that delayed the emergence of most mosquito species. No Mansonia were detected in our regular adult trapping until June. Overall, the number of Mansonia trapped in 2017 was much lower than previous years, even though there was more standing water throughout the Lower Mainland in 2017 than the previous two years. In 2017, 664 mosquitoes were trapped at MA-2/ TOL-1A at the peak of emergence on June 28 th. In 2016, 1,868 Mansonia were trapped on June 20 th, with several trapping nights reaching well over 1000 mosquitoes. Another key species to emerge in greater numbers every several years is Aedes sticticus. Figure 8 shows the numbers of the three Aedes species of concern, Aedes sticticus, Aedes vexans and Aedes dorsalis, caught in adult traps between 2008 and In 2017, Aedes sticticus was trapped in the highest numbers since tracking began in Table 6: Metro Vancouver Nuisance Adult Trapping Results 2017 Date Culex Site ID Total Mosquitoes Identified Unknown Aedes aloponotum Aedes canadensis Aedes cinereus Aedes dorsalis Aedes fitchii Aedes increpitus 05/11/2017 SR-1a /11/2017 SR-2a /11/2017 TOL-1a /11/2017 TOL-3a /15/2017 COQ-1A /15/2017 COQ-2A /15/2017 MR-2a /15/2017 MR-3a /15/2017 PM-1a /15/2017 PM-3A Total Aedes punctor Aedes sticticus Aedes vexans Anopheles earlei Anopheles punctipennis Mansonia perturbans Culex pipiens Culex tarsalis Culiseta impatiens Culiseta incidens Culiseta inornata Culiseta minnesotae Culiseta morsitans 21

22 Date Culex Site ID Total Mosquitoes Identified Unknown Aedes aloponotum Aedes canadensis Aedes cinereus Aedes dorsalis Aedes fitchii Aedes increpitus 05/24/2017 TOL-1a /24/2017 TOL-3a /26/2017 COQ-1A /26/2017 COQ-2A /26/2017 MR-2a /26/2017 MR-3a /26/2017 PM-1a /26/2017 PM-2a /26/2017 SR-2a /26/2017 SR-3a Total Aedes punctor Aedes sticticus Aedes vexans Anopheles earlei Anopheles punctipennis Mansonia perturbans Culex pipiens Culex tarsalis Culiseta impatiens Culiseta incidens Culiseta inornata Culiseta minnesotae Culiseta morsitans Date Culex Site ID Total Mosquitoes Identified Unknown Aedes aloponotum Aedes canadensis Aedes cinereus Aedes dorsalis Aedes fitchii Aedes increpitus 06/05/2017 SR-1a /05/2017 SR-2a /05/2017 TOL-1a /05/2017 TOL-3a /08/2017 COQ-1A /08/2017 COQ-2A /08/2017 MR-2a /08/2017 MR-3a /08/2017 PM-1a /08/2017 PM-2a Total Aedes punctor Aedes sticticus Aedes vexans Anopheles earlei Anopheles punctipennis Mansonia perturbans Culex pipiens Culex tarsalis Culiseta impatiens Culiseta incidens Culiseta inornata Culiseta minnesotae Culiseta morsitans Date Culex Site ID Total Mosquitoes Identified Unknown Aedes aloponotum Aedes canadensis Aedes cinereus Aedes dorsalis Aedes fitchii Aedes increpitus 06/19/2017 SR-2a /19/2017 SR-3a /19/2017 TOL-1a /19/2017 TOL-3a /22/2017 COQ-1A /22/2017 COQ-2A /22/2017 MR-2a /22/2017 MR-3a /22/2017 PM-1a /22/2017 PM-2a Total Aedes punctor Aedes sticticus Aedes vexans Anopheles earlei Anopheles punctipennis Mansonia perturbans Culex pipiens Culex tarsalis Culiseta impatiens Culiseta incidens Culiseta inornata Culiseta minnesotae Culiseta morsitans 22

23 Date Culex Site ID Total Mosquitoes Identified Unknown Aedes aloponotum Aedes canadensis Aedes cinereus Aedes dorsalis Aedes fitchii Aedes increpitus 07/04/2017 SR-2a /04/2017 SR-3a /04/2017 TOL-1a /04/2017 TOL-3a /06/2017 COQ-1A /06/2017 COQ-2A /06/2017 MR-2a /06/2017 MR-3a /06/2017 PM-1a /06/2017 PM-2a Total Aedes punctor Aedes sticticus Aedes vexans Anopheles earlei Anopheles punctipennis Mansonia perturbans Culex pipiens Culex tarsalis Culiseta impatiens Culiseta incidens Culiseta inornata Culiseta minnesotae Culiseta morsitans Date Culex Site ID Total Mosquitoes Identified Unknown Aedes aloponotum Aedes canadensis Aedes cinereus Aedes dorsalis Aedes fitchii Aedes increpitus 07/17/2017 SR-2a /17/2017 SR-3a /17/2017 TOL-1a /17/2017 TOL-3a /18/2017 COQ-1A /18/2017 COQ-2A /18/2017 MR-2a /18/2017 MR-3a /18/2017 PM-1a /18/2017 PM-2a Total Aedes punctor Aedes sticticus Aedes vexans Anopheles earlei Anopheles punctipennis Mansonia perturbans Culex pipiens Culex tarsalis Culiseta impatiens Culiseta incidens Culiseta inornata Culiseta minnesotae Culiseta morsitans Date Culex Site ID Total Mosquitoes Identified Unknown Aedes aloponotum Aedes canadensis Aedes cinereus Aedes dorsalis Aedes fitchii Aedes increpitus 07/31/2017 SR-2a /31/2017 SR-3a /31/2017 TOL-1a /31/2017 TOL-3a /01/2017 COQ-1A /01/2017 COQ-2A /01/2017 MR-2a /01/2017 MR-3a /01/2017 PM-1a /01/2017 PM-2a Total Aedes punctor Aedes sticticus Aedes vexans Anopheles earlei Anopheles punctipennis Mansonia perturbans Culex pipiens Culex tarsalis Culiseta impatiens Culiseta incidens Culiseta inornata Culiseta minnesotae Culiseta morsitans 23

24 Date Culex Site ID Total Mosquitoes Identified Unknown Aedes aloponotum Aedes canadensis Aedes cinereus Aedes dorsalis Aedes fitchii Aedes increpitus 08/14/2017 SR-2a /14/2017 SR-3a /14/2017 TOL-1a /14/2017 TOL-3a /15/2017 COQ-1A /15/2017 COQ-2A /15/2017 MR-2a /15/2017 MR-3a /15/2017 PM-1a /15/2017 PM-2a Total Aedes punctor Aedes sticticus Aedes vexans Anopheles earlei Anopheles punctipennis Mansonia perturbans Culex pipiens Culex tarsalis Culiseta impatiens Culiseta incidens Culiseta inornata Culiseta minnesotae Culiseta morsitans Table 7: Results of Adult Trapping near Cattail Treatment Sites in the Township of Langley 2017 Date Culex Site ID Total Mosquitoes Identified Aedes aboriginis Aedes sticticus 06/16/2017 MA /16/2017 MA /16/2017 MA /16/2017 MA /28/2017 MA /28/2017 MA-3A /28/2017 MA /28/2-017 MA /13/2017 MA /13/2017 MA /13/2017 MA /13/2017 MA /26/2017 MA /26/2017 MA /26/2017 MA /26/2017 MA Total Aedes vexans Anopheles earlei Anopheles punctipennis Mansonia perturbans Culex pipiens Culex tarsalis Culiseta impatiens Culiseta incidens Culiseta morsitans 24

25 Figure 8: Numbers of Aedes species in Adult Traps KEY FINDINGS FROM ADULT MOSQUITO SURVEILLANCE Eighty trap nights were conducted in 2017 collecting a total of 4,017 adult mosquitoes, down from 6,668 collected in % of specimens identified were the nuisance mosquito species Mansonia perturbans and 6% were potential high risk West Nile virus vector species (Culex pipiens and Culex tarsalis). Mansonia perturbans is not a West Nile virus vector species, but it is an aggressive daytime biter of humans. Numbers are down from 88% in 2016 to 15% in 2017 of all adults collected. There were 16 additional trapping nights near Cattail Treatment Sites in the Township of Langley where 1327 of the 1829 (73%) of adult mosquitoes were identified as Mansonia perturbans, compared to 83% in ,931 (48% of the total) Aedes sticticus were collected, which is significant as this species is known to be an aggressive daytime biter. 25

26 3.3 Larvicide Treatment Between May 1 st and August 8 th, 2.80 kg of VectoBac 200G and 17.0 kg of Vectolex CG were applied in the Metro Vancouver nuisance control program including Northwest Langley WWTP and cattail treatments (Tables 8 through 12), not including the two aerial treatments of Macmillan Island. In 2017 flood conditions throughout the month of June led to two aerial treatments of Macmillan Island, one on June 9 th and 12 th and the second one on June 29 th. On June 9 th and 12 th Culex used kg of VectoBac to treat hectares (Figure 9). On June 29 th Culex used kg of VectoBac to treat hectares (Figure 10). The label for Vectolex CG was changed in 2015 which prohibited retreatment within two weeks. This meant that Vectolex CG could not be applied at either Northwest Langley WWTP or the Surrey salt marshes at the same frequency as in previous years. Culex alternated use of Vectolex CG and VectoBac 200G each week to comply with the new restrictions. Vectolex CG has also been shown to be much more effective at treating Mansonia perturbans than VectoBac 200G, thus cattail sites were treated only every other two weeks between May and August, for a total of 6 treatment rounds. Date Table 8: VectoBac Treatments in Maple Ridge 2017 Culex Site ID Area Treated (m2) Amount Used (g) Pesticide Type 30/06/2017 MR Vectobac 200G 13/07/2017 MR Vectobac 200G 24/07/2017 MR Vectobac 200G 24/07/2017 MR Vectobac 200G Total

27 Date Table 9: VectoBac Treatments in Surrey 2017 Culex Site ID Area Treated (m2) Amount Used (g) 01/05/2017 SR Vectolex CG 01/05/2017 SR Vectolex CG 15/05/2017 SR Vectolex CG 23/05/2017 SR Vectobac 200G 05/06/2017 SR Vectobac 200G 05/06/2017 SR Vectobac 200G 05/06/2017 SR Vectobac 200G 05/06/2017 SR Vectobac 200G 19/06/2017 SR Vectobac 200G 04/07/2017 SR Vectobac 200G 04/07/2017 SR Vectobac 200G 25/07/2017 SR Vectobac 200G Total Table 10: VectoBac Treatments in the Township of Langley 2017 Date Culex Site ID Area Treated (m2) Amount Used (g) Pesticide Type 07/06/2017 TOL Vectobac 200G 14/06/2017 TOL Vectobac 200G 16/06/2017 TOL Vectobac 200G 16/06/2017 TOL Vectobac 200G 23/06/2017 TOL Vectobac 200G 30/06/2017 TOL Vectobac 200G 30/06/2017 TOL Vectobac 200G 04/07/2017 TOL Vectobac 200G 07/07/2017 TOL Vectobac 200G 07/07/2017 TOL Vectobac 200G 14/07/2017 TOL Vectobac 200G 14/07/2017 TOL Vectobac 200G 17/07/2017 TOL Vectobac 200G 17/07/2017 TOL Vectobac 200G 18/07/2017 TOL Vectobac 200G 18/07/2017 TOL Vectobac 200G 19/07/2017 TOL Vectobac 200G 01/08/2017 TOL Vectobac 200G Total

28 Table 11: VectoBac Treatments of Metro Vancouver Parks 2017 Date Culex Site ID Area Treated (m2) Amount Used (g) Pesticide Type Table 12: Vectolex Treatments of Cattails for Mansonia perturbans 2017 Metro Vancouver Park 05/06/2017 TOL Vectobac 200G Derby Reach 27/06/2017 TOL Vectobac 200G Derby Reach Total 2 2 Date Culex Site ID Area Treated (m2) Amount Used (g) Pesticide Type Metro Vancouver Park 02/06/2017 TOL Vectobac 200G Brae Island 07/06/2017 TOL Vectobac 200G Brae Island 07/06/2017 TOL Vectobac 200G Brae Island 07/06/2017 TOL Vectobac 200G Brae Island 14/06/2017 TOL Vectobac 200G Brae Island Total Culex Site ID Date Area Treated (m2) Amount used (g) Pesticide Type COQ /06/ Vectolex CG COQ /06/ Vectolex CG COQ /06/ Vectolex CG COQ /07/ Vectolex CG Total

29 Date Culex Site ID Area Treated (m2) Amount Used (g) Pesticide Type 01/06/2017 MR Vectolex CG 01/06/2017 MR Vectolex CG 01/06/2017 MR Vectolex CG 15/06/2017 MR Vectolex CG 15/06/2017 MR Vectolex CG 15/06/2017 MR Vectolex CG 29/06/2017 MR Vectolex CG 29/06/2017 MR Vectolex CG 29/06/2017 MR Vectolex CG 13/07/2017 MR Vectolex CG 13/07/2017 MR Vectolex CG 13/07/2017 MR Vectolex CG 08/08/2017 MR Vectolex CG 08/08/2017 MR Vectolex CG 08/08/2017 MR Vectolex CG Total Date Culex Site ID Area Treated (m2) Amount Used (g) Pesticide Type Metro Vancouver Park 26/05/2017 MA-3A Vectolex CG Derby Reach 08/06/2017 MA Vectolex CG Derby Reach 21/06/2017 MA-3A Vectolex CG Derby Reach Total Date Culex Site ID Area Treated (m2) Amount Used (g) 30/05/2017 SR Vectolex CG 13/06/2017 SR Vectolex CG 26/06/2017 SR Vectolex CG 10/07/2017 SR Vectolex CG Total

30 Date Culex Site ID Area Treated (m2) Amount Used (g) Pesticide Type 25/05/2017 MA Vectolex CG 25/05/2017 MA Vectolex CG 25/05/2017 MA Vectolex CG 25/05/2017 MA Vectolex CG 25/05/2017 MA Vectolex CG 26/05/2017 MA Vectolex CG 26/05/2017 MA Vectolex CG 26/05/2017 MA Vectolex CG 26/05/2017 MA Vectolex CG 02/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 08/06/2017 MA Vectolex CG 09/06/2017 MA Vectolex CG 09/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 30

31 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 21/06/2017 MA Vectolex CG 30/06/2017 TOL Vectolex CG 07/07/2017 MA Vectolex CG 07/07/2017 MA Vectolex CG 07/07/2017 MA Vectolex CG 07/07/2017 MA Vectolex CG 07/07/2017 MA Vectolex CG 07/07/2017 MA Vectolex CG 07/07/2017 MA Vectolex CG 07/07/2017 MA Vectolex CG 07/07/2017 MA Vectolex CG 07/07/2017 MA Vectolex CG 10/07/2017 TOL Vectolex CG 14/07/2017 TOL Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 21/07/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG 04/08/2017 MA Vectolex CG Total

32 Figure 9: Aerial Treatment of Brae Island June 9 th and June 12 th 2017 Figure 10: Aerial Treatment of Brae Island June 29 th

33 3.4 Nuisance Mosquito Hotline In 2017, the Nuisance Mosquito Hotline remained a very useful information resource for the public. The hotline maintained a number for local calls ( ) and for toll-free long distance calls ( ). Inquiries were answered in person between 8am and 4pm Monday to Friday. Outside office hours a voice message was taken and responded to promptly the following day. The link to this information can be accessed by clicking the Mosquito Hotline button at the bottom of the Culex Environmental home page ( Residents calling the Hotline with concerns regarding mosquitoes in their area were asked a series of questions to obtain more information about the site, and given information (Appendix L). If requested, Culex staff visited the area of concern and conducted a site assessment (Appendix M). If, at the time of assessment, the problem area was located on non-municipal land, the property owner was advised on mosquito management techniques that he or she could apply. While follow up monitoring was not conducted on non-municipal land in Maple Ridge, Surrey, Coquitlam or Pitt Meadows, it was carried out on non-municipal lands in Langley when an initial assessment identified a potential nuisance mosquito development site. These sites were added to our database of sample sites and visited regularly. Culex Environmental received a total of 110 concern alerts (either by phone or ), summarized below, during the 2017 program (Table 13). 96 of the calls came from Fort Langley, one from Metro Vancouver Parks, three came from Maple Ridge, seven from Surrey, and one from Coquitlam. Historically, the number of concern calls and the peak river level at the Mission gauge are closely correlated (Figure 3). A total of 27 sites were created as a result of responses to the concern calls received in These sites will be reevaluated to confirm their development habitat validity in 2018 and will be added to the routine monitoring schedule should they again be identified as potential habitat. A summary of concern calls is listed below. Maps showing locations of concern calls from 2012 to 2017 can be found in Appendix H. Table 13: Concern Calls Summary 2017 Date Details Description of Site found Municipality Source Winter 2016 Four new retention ponds located near the intersection of Highway 17 and Highway 1 were brought to our attention. The sites were visited on May 12, No mosquitoes were found, however the ponds are potential mosquito habitat. Three sites were created SR-148, SR-146, SR-145. The fourth pond is inaccessible at this time due to construction. City of Surrey Surrey Coordinator 25-May May May May-17 A resident requested that we check out a pond in their backyard. A resident called for a site visit to show us around property. Site has stream with depressions and standing water, a pond and a ditch in front of the house. A resident of the Township of Langley called to inquire if we were out monitoring yet and if it will be a bad year for mosquitoes. A resident called to request a site visit for an open ditch in front of house. The site was visited on May 25, and two new sites were created at two separate ponds, TOL-999 and TOL-998. Four new sites were created- TOL-1015, TOL-1014, TOL-1016, TOL-1017 Called back and left a message. The ditch is at the corner of Balsam and Woodcrest in south Surrey, one site was made SR-111. Township of Langley Township of Langley Township of Langley Surrey Hotline Hotline Hotline Hotline 33

34 Date Details Description of Site found Municipality Source 09-Jun Coordinator alerted us to a potential site in a pond near A St. in Langley, near the Sharon Village Townhouse Complex. A site visit on June 9th found a pond with low water levels that were potential habitat, three sites were made. TOL-404, TOL-405, TOL-406. Township of Langley Coordinator 15-Jun Jun Resident called about a body of water across from house. A site visit was made on June 16, and a new site was created, TOL-707. The water body is fish bearing and no mosquitoes were found, but the area is potential habitat. Mosquitoes are out in Fort Langley. Concerned Called back and gave more information about our about illness transmitted by mosquitoes and if we program. will be spraying this year. Township of Langley Township of Langley Hotline TOL Website 26-Jun 24 separate calls. People wanted an update on what TOL is doing to control the mosquitoes and/ or to notify us that there are a lot of mosquitoes. Called back with more information about our program. Township of Langley TOL Website/ Hotline 26-Jun Called about standing water underneath a stand of trees. A site visit on June 27th found no standing water in the location described. There were lots of adults flying around and there was an inaccessible fenced area that may have sites- unable to confirm. Township of Langley Hotline 26-Jun Called about standing water at Cassimeer and Jenny Lewis in Bedford Landing. A site visit on June 27th found no standing water in the location described. The area is close to several other sites. No adults were flying around. Township of Langley Hotline 26-Jun Called about a ditch on 240th st. with standing water. A site visit on June 27th found a very low level of water in the ditch. The water was too low to contain mosquito larvae at this time. Township of Langley Hotline 26-Jun 26-Jun 27-Jun Called about park in downtown Fort Langley and wanted us to check for standing water. Called about standing water by Billy Brown Road, off of 96th ave. 37 separate calls. People wanted an update on what TOL is doing to control the mosquitoes and/ or to notify us that there are a lot of mosquitoes. A site visit on June 27 did not find any standing water in and around the park. A site visit on June 27th did not find standing water in the area described. Other sites already exist throughout Bedford Landing as well. Called back. Site visit not necessary. Township of Langley Township of Langley Township of Langley Hotline Hotline TOL Website/ Hotline 27-Jun 27-Jun Homeowner wanted us to check standing water at a bridge at 88th and Glover Road. Caller wanted us to check out site in Noel Booth Community park. No larvae were found but there were adults around. The water level had gone down a lot at the time of visit. Water was slowly moving. A site was made TOL Two sites were made in a pond in a park, TOL-002 and 003. No larvae were found on June 28th. Township of Langley Township of Langley Hotline Hotline 27-Jun 28-Jun Called about standing water in ditches near property. Wanted to know if we have sites in park area of Bedford Landing Site visit on June 28th did not find mosquitoes but three sites were made in ditches near the property, TOL-1011,TOL-1018, TOL Confirmed that we do have sites and are sampling in the area. Township of Langley Township of Langley Hotline Hotline 28-Jun 6 separate calls. People wanted an update on what TOL is doing to control the mosquitoes and/ or to notify us that there are a lot of mosquitoes. Called back with more information about our program. Township of Langley Hotline 28-Jun Wanted to know if we treat Metro Vancouver Parks. Confirmed that we do have sites in some parks. 29-Jun Called about standing water near property. A site visit on June 30 found standing water in reed canary grass behind property. A site MR-108 was made. 29-Jun 30-Jun Caller has a green space behind property, currently a construction site and temporary. Called about the Derby Reach Houston Trail that has lots of mosquitoes. On June 30 a site visit found a pool of water in construction site with mosquitoes. A site MR-103 was made. Gave more information about our program and monitoring efforts in Fort Langley. Township of Langley Maple Ridge Maple Ridge Township of Langley Hotline Hotline Hotline Hotline 34

35 Date Details Description of Site found Municipality Source 04-Jul Requested a site visit to ditches near house on 179 st. A site visit on July 5th did not find any potential Surrey Hotline near 99 ave. mosquito habitat- all ditches in the area were dry. 04-Jul Called to report high numbers of mosquitoes. A message was left for the caller about our mosquito control program. 04-Jul A homeowner called to request a site visit to a water body in their backyard. A site visit on July 5th found a water body that contained fish. No larvae were found. Homeowner is filling in site, no site was made. 06-Jul Asking about mosquito repellant options. Gave information about options for preventing mosquito bites. 06-Jul Reporting high numbers of mosquitoes. Discussed the Culex mosquito control program with the caller. 06-Jul Resident wanted us to check out an area behind house where beavers have dammed up a creek, which has some standing water. A site visit on July 7th did not find any larvae as the water level was low and flowing. There is a possibility of a higher water level in the spring, however, everything is connected to a flowing creek, which is fish bearing. The beaver damn was not blocking the flow of water completely. 07-Jul Requested a site visit for pond in front of property. A site visit on July 10th found a pond with cattails for which Culex site TOL-341 already exists. The pond was treated with vectolex for the cattail control program. Township of Langley Township of Langley Surrey Township of Langley Township of Langley Township of Langley Hotline Hotline Hotline Hotline Hotline 07-Jul Requested that Culex call or stop by when next in Maple Ridge. An attempt to contact the resident and discuss a site visit was made on July 13th and July 14th. The resident did not get back to us. The possible site is along Kanaka Creek, which is fish bearing and cannot be treated. Maple Ridge Hotline 07-Jul Request for a site visit to some open ditches surrounding resident's house. A site visit on July 13th found 3 ditches, 1 of which had water in it. A new site was made, MR-130, to include all three connected ditches. 10-Jul Reporting high numbers of mosquitoes. Discussed the Culex mosquito control program with the caller. 11-Jul Called to ask what the state of Brae Island is as they Gave information about recent treatments and what we would like to go camping there. are finding in the area. 17-Jul Reporting high numbers of mosquitoes. A message was left for the caller about our mosquito control program. 17-Jul Called about a pool of water near an empty property. Called back and explained that we can't treat on private property without permission from the City. Passed the request onto the City of Coquitlam. 17-Jul Reporting a storm drain in alley. A site visit on July 18th found no visible ditches and possible breeding sites. There was one storm drain, which is not part of the Culex sampling protocol at this time. 18-Jul Wanted to confirm a site on property. Confirmed that there is a site at the resident's property, TOL Jul Caller wanted us to check some standing water at 75th A visit to this site found very low standing water, which and 232 st. was not deep enough to sample. However, this site will be flagged for next spring when the water levels rise. Maple Ridge Township of Langley Township of Langley Township of Langley Coquitlam Surrey Township of Langley Township of Langley Hotline Hotline Hotline Hotline Hotline Hotline Hotline Hotline 19-Jul A business owner in Fort Langley called about lots of adults flying around in downtown Fort Langley. A site visit on July 20 did not find any new sites, however there are active sites nearby that are being treated as needed, TOL-1090 and TOL Township of Langley Call to Township of Langley 20-Jul A request by from Metro Vancouver to check out sites in the Boundary Bay area. On July 20th 7 previous Boundary Bay sites were visited as well as a survey of the park. Mosquito larvae were found at one site that was treated. Metro Vancouver Parks Metro Vancouver coordinator 25-Jul Inquiry about where to buy Bti. Called back and left a message. Hotline 26-Jul ed to ask what was being done about mosquitoes Replied back with information about Culex monitoring Township of in Fort Langley. the area. Langley 26-Jul Resident has a green belt behind house and lots of mosquitoes. On July 27th a site visit to the area found that the entrance to a trail down to the green belt was fenced off and locked. The resident was asked more information about how to access site, and Culex will do another site visit if the resident notifies us of a way to access site/ that it is not private property. Surrey 31-Jul Received an inquiry about treating mosquito habitat in resident's backyard. Called back and left a message with resident that Culex currently does not treat habitat on private property Surrey Hotline

36 3.5 Public Education and Communications The public plays a key role in helping to reduce nuisance mosquito development sites. It is important that residents have a clear understanding of mosquito behavior and biology, the benefits realized by their control and the role that people have in preventing certain mosquito-borne illnesses. Public Education Events Over the spring and summer of 2017, Culex Environmental staff attended five community events: the Kanaka Creek Watershed Stewardship Center Opening event in Maple Ridge, Pitt Meadows Day, the Fort Langley May Day Festival, the Teddy Bear Picnic in Coquitlam and the Surrey Canada Day event. These public events catered to all ages. Culex Environmental staff set up informational display booths which presented posters (Appendix I) and also provided brochures and children s workbooks. All visitors were free to help themselves to the newly revised public education pamphlet (Appendix I) and bookmarks (Appendix J). Children were given the Biter Fighters workbook (Appendix K). Staff members interacted with visitors, answering questions and concerns regarding the Nuisance Mosquito Control Program, specifically on ways to reduce the occurrence of mosquito bites and eliminate household mosquito breeding habitats. At all events Culex set up a dissecting microscope for people to get a closer look at some mosquito larvae. The microscope was a hit at all of the events. There was even a long line to use the microscope for while during the Teddy Bear Picnic event. 36

37 4.0 Discussion and Recommendations Continued monitoring of each species helps to reveal changes in their behavior and adaptation to changing conditions, which is critical to the success of any mosquito nuisance control program. Over the years we have continued to refine our monitoring and this has provided essential knowledge about the distribution of different species, picked up the resurgence of some species and the decline of others as well as revealing the existence of completely new species. In 2008, Culex enhanced the program to target habitats of a re-emerging nuisance mosquito, Aedes sticticus. In 2014, Culex discovered a new species to British Columbia, Aedes japonicus, and research efforts focused on monitoring and looking for this species around the Lower Mainland. As per our 2015 recommendations, Culex implemented a treatment protocol in 2016 targeting cattail habitat throughout all five municipalities to control the nuisance mosquito Mansonia perturbans. In 2017, a reduced number of Mansonia perturbans trapped indicated that our cattail treatment program has had some effect on reducing the established population. In 2014, Culex discovered Aedes japonicus in British Columbia for the first time, in Maple Ridge and has continued to monitor for the presence of this species. In 2017 several Aedes japonicus were identified in a sample from the Township of Langley, near the Fort Museum. Aedes japonicus is of concern as it is a potential disease vector. Our continuing monitoring and identification efforts will allow us to further track this species should it begin to establish populations in more locations. 37

38 4.1 Mansonia perturbans With higher water levels in 2011 and 2012, Mansonia perturbans established a significant population in the Lower Mainland (Jackson et al. 2011, Jackson et al. 2012, Jackson et al. 2013). Due to the low snow pack in the early part of 2015, it was determined that research into Mansonia perturbans would be postponed because populations of this species were expected to be quite low in drier years, although in fact we were proven wrong on this assumption. It is likely that cattail habitats in Langley are more influenced by rainfall than by river levels, and it is clear that even dry years can produce high numbers of Mansonia. June and July 2016 received much more rainfall than in 2015 and our adult trapping results again showed high numbers of Mansonia emergence. In 2017, which had similarly high precipitation to 2016, Culex continued the cattail site treatment program that was initiated in Figure 11 below shows that, based on our adult trap results, our cattail treatments seem to have been effective at reducing established larval populations of Mansonia perturbans, as these are the lowest numbers that have been seen in several years. Figure 11: Average number of Mansonia perturbans in adult traps in 2013 to

39 4.2 Climatic Factors It is well known that changes in climatic conditions and environmental factors strongly influence the abundance of nuisance mosquitoes from year to year. With common nuisance mosquitoes in the Fraser Valley floodplain, such as Aedes vexans and Aedes sticticus, egg production usually commences after the initial adult emergence in late June and early July, with each female laying hundreds of eggs over an extensive area. Preferred egg-laying habitat ranges from areas that are flooded annually, to areas that may flood once every five to ten years. Dormant eggs will hatch according to a combination of environmental triggers, including exposure to water, oxygen content, and water temperature (Horsfall et al. 1973). Hatching usually occurs around 14 C (Horsfall et al. 1973, Dr. P. Belton pers. comm.). Several environmental factors may be used to predict a nuisance mosquito outbreak. The severity of the spring freshet and river level can be tracked by monitoring the winter snow pack accumulation, air temperatures and precipitation, particularly during May and early June. Heavy snow pack accumulation followed by warm weather and rain-on-snow events up in the mountains in May can lead to an extremely high freshet in early June. When a high freshet is followed by above average air temperatures in excess of 15 C, eggs are triggered to hatch in very large numbers. In 2012 the freshet was of unusually high amplitude and duration (Figure 17), with extensive areas remaining flooded for much longer than usual throughout the Lower Mainland with major inundations across River Road in Langley and the adjacent farmland. This provided the conditions for Mansonia perturbans to thrive and become a major nuisance species in Metro Vancouver. In 2013, the freshet was early, starting the life cycle of mosquitoes a few weeks earlier than normal (Figure 16). A well-timed aerial treatment successfully controlled the mosquitoes for the 2013 season. In 2014, the freshet peaked in early June, with the aerial treatment occurring soon after (Figure 15). Rain events after the freshet caused re-flooding of previously treated areas and may have led to the increased number of Aedes species detected in Fort Langley. Based on adult trap numbers, the primary nuisance problem was again Mansonia perturbans for the third year in a row. In 2015, water and snow pack levels were below normal. The Fraser River peaked at 4.6m at the Mission gauge, the lowest in five years, and as a result, an aerial campaign was determined to be unnecessary (Figure 14). In 2016, snow pack levels were much higher than in 2015 (Figure 13), however the Fraser River peaked at 3.7m at the Mission gauge, a meter lower than in Temperatures in the early spring reached record levels, thus causing the snowpack to begin melting earlier and more gradually so that no peak river level occurred after the freshet. No aerial treatment was necessary. In 2017, the snow pack level was the highest it has been since 2012 (Figure 12) and the river level peaked at 5.6 meters on June 4 th. Precipitation was extremely high in the spring through to mid-may in 2017 compared to seasonal means over the past ten years, however, due to very cold temperatures in May and early June, the water remained too cold for larvae to hatch. By mid-june, two main factors, increasing river level and higher temperature, coincided to produce a large emergence of adults from the floodplain over a period of several weeks. 39

40 Figure 12: Metro Vancouver River Level, Temperature, Precipitation and Snowpack

41 Figure 13: Metro Vancouver River Level, Temperature, Precipitation and Snowpack

42 Figure 14: Metro Vancouver River Level, Temperature, Precipitation and Snowpack

43 Figure 15: Metro Vancouver River Level, Temperature, Precipitation and Snowpack

44 Figure 16: Metro Vancouver River Level, Temperature, Precipitation and Snowpack

45 Figure 17: Metro Vancouver River Level, Temperature, Precipitation and Snowpack

46 4.3 Program Effectiveness and Recommendations Ultimately, the goal of the Nuisance Program is to reduce the number of nuisance species mosquitoes to tolerable levels of human annoyance. Several factors contribute to the size of nuisance mosquito populations each year, such as snowpack, river levels, temperature, and the success of the previous year s mosquitoes in laying eggs. Culex uses the following indicators to evaluate the effectiveness of the Nuisance Program: Comparison of Pre- and Post-Treatment Larval Numbers The effectiveness of the larvicide treatment is shown by a comparison of the average number of larvae sampled before and after treatment (Figure 18). When evaluating larvicide effectiveness, it is important to recognize that the larvicide does not affect 1st instar larvae that hatch from eggs after treatment is applied. The larvae do not consume significant food at this stage and the larvicide disperses and becomes ineffective within 48 hours. The result is that there are often a number of larvae that are unaffected by earlier treatments, but will be susceptible to the next treatment, which is why sites are monitored every seven to ten days. As was seen in 2015, it appears that the switch to alternating between Vectolex and Vectobac at the Surrey salt marsh had a negative impact on the level of control achieved in previous years. However, in 2017 the pools at the Surrey salt marsh remained dry for much of the season and very few treatments were needed. In a future wetter year we also recommend manually removing the larvae and pupae from the margins of the waterbodies, which is actually relatively easy to achieve around small salt marsh depressions and will implement this if necessary in Adult Sampling Results In 2017, the number of nuisance species adults was down by about 2600 individuals from The increase in adults came from Aedes species. Due to our treatment program in 2016 the established populations of Mansonia perturbans appear to have decreased in number. Culex will continue this treatment program in Concern Calls The number of concern calls gives a rough indication of the level of nuisance experienced by the public. In 2017, the Hotline recorded 110 calls, compared to 105 calls in 2012, which was a similar year in terms of weather conditions. 46

47 Figure 18: Average Number of Larvae Before and After Treatment Long-Term Program Effectiveness As mentioned above, larvicide is known to have little effect on first instar larvae that hatch from eggs after treatment is applied. The result is that there are often a number of larvae that are unaffected by earlier treatments, but will be susceptible to the next treatment, which is why sites are monitored every seven to ten days. The efficacy of each year is summarized in Figure

48 Figure 19: Average Number of Larvae found Before and After Treatment across all Four Municipalities KEY RECOMMENDATIONS FOR NUISANCE PROGRAM IN 2018 Continue monitoring, surveillance and treatment using the IMMPACT approach to continue an effective Metro Vancouver Nuisance Mosquito Program Continue monitoring the Surrey salt-marsh sites weekly throughout the entire summer to control Aedes dorsalis. Include physical removal as a control measure for these sites to improve efficacy. Continue treatment of Mansonia perturbans sites in all municipalities where cattails are present with BSph (Bacillus sphaericus). Bti (Bacillus thuringiensis israelensis) has been shown to be ineffective in controlling this species. Continue monitoring numbers with adult traps. 48

49 4.5 West Nile Virus Update CANADA 2017 As of October 7, 2017, a total of 152 human clinical cases of West Nile virus have been reported to the Public Health Agency of Canada: Quebec (12), Ontario (139), Manitoba (3), Alberta (5) and BC (1). Of these, fifty-four cases (34 %) were classified as West Nile virus Neurological Syndrome. Six fatal cases have been reported. In addition, six West Nile virus asymptomatic infections have been reported. As of October 7, 2017, 544 (3.13%) out of 17,373 mosquito pools have tested positive for WNV in Canada: Saskatchewan (10), Manitoba (41), Ontario (429) and Quebec (84). As of October 7, 2017, the Public Health Agency of Canada has examined a total of 183 dead birds for WNV, of which 126 (69%) dead birds have tested positive for WNV: Manitoba (2), Saskatchewan (9), Ontario (37), and Quebec (78). As of October 7, 2017, forty-seven horses with WNV infection have been reported to the Canadian Food Inspection Agency by various provincial/private animal health laboratories. These are preliminary data under validation: British Columbia (4), Alberta (9), Manitoba (1), Ontario (18), Saskatchewan (8) and Quebec (7). Table 14: Total Number of human, mosquito, bird and horse cases of West Nile virus in British Columbia since 2007 Year Human Mosquito Bird Horse 2007 (19) (1) (1) Total 5(21) Numbers in brackets indicate travel acquired cases. 49

50 UNITED STATES 2017 As of October 17, 2017, the Centers for Disease Control and Prevention have reported a total of 1,502 human clinical cases of West Nile virus disease in 42 states in the US, including the following border states: Washington (9), Idaho (11), Montana (10), New York (36), North Dakota (61), Minnesota (23), Michigan (38), and Vermont (1). Of these, 987 (66%) were classified as neuroinvasive disease and 515 (34%) were classified as non- neuroinvasive disease. Eighty-six fatal cases have been reported. In addition, 202 presumptive viremic blood donors have been identified. Table 15: Total number of human cases and fatalities due to West Nile virus since introduction in New York in 1999 Year Canada United States Human Cases Fatalities Human Cases Fatalities , , , , , , , , , , , , , , Total Zika Virus Update Canada As of September , 523 travel-related cases, 4 sexually transmitted cases and 2 reports of maternal-to-fetal transmission of Zika virus have been detected in Canada. There's ongoing low risk to Canadians travelling to countries or areas in the U.S. with reported mosquito-borne Zika virus. 50

51 At this time, according to the British Columbia Center for Disease Control, Zika virus is considered to be a travel related infection. United States As of October 18, 2017, there have been 225 locally acquired mosquito-borne cases reported in the US States. There have been 5,264 travel-associated cases. In total, there have been 4,575 cases reported including 48 that were sexually transmitted. 51

52 5.0 References BC Ministry of Environment Integrated Pest Management Act and Regulation Mosquito Management Sector Review Paper. 25pp. Belton, P The Mosquitoes of British Columbia. BC Provincial Museum, Handbook No Bidlingmayer, W. L Larval development of Mansonia mosquitoes in central florida.28, Retrieved from Ellis, R Municipal Mosquito Control Guidelines. Health Canada Bureau of Infectious Diseases. 54pp. Floore, T. and Ward, R Evaluation of Bacillus sphaericus against Mansonia dyari larvae in phosphate lakes in Polk County, Florida. Journal of the American Mosquito Control Association. 25: Hearle, E Mosquitoes of the Lower Fraser Valley B.C. and their control. Natural Resource Council Report No 17, 94pp. Horsfall, W. R., Fowler, H. W. Jr, Moretti, L. J., and Larsen, J. R Bionomics and embryology of the inland floodwater mosquito. Univ. Illinois Press, Chicago. Jackson, M., Evelyn, M., Gow, J., Meikleham, N., Waldock, S., and Fladmark, D Metro Vancouver 2007 Integrated Mosquito Management Program - Nuisance Mosquito Control Program. Jackson, M., Evelyn, M., McMahon, S., Meikleham, N., Fladmark, D., and Sheppard, J. 2008a. Metro Vancouver Fraser Foreshore Survey Report. Jackson, M., Evelyn, M., Gow, J., Meikleham, N., McMahon, S., Fladmark, D., and Sheppard, J. 2008b. Metro Vancouver 2008 Integrated Mosquito Management Program. Nuisance Mosquito Control Program. September 2008 Jackson, M., Evelyn, M., Gow, J., McMahon, S., Fladmark, D., and Sheppard, J Metro Vancouver 2009 Integrated Mosquito Management Program. Nuisance Mosquito Control Program. November 2009 Jackson, M., McMahon, S., Fladmark, D., and Sheppard, J Metro Vancouver 2010 IMMPACT. Nuisance Mosquito Control Program. November Jackson, M., McMahon, S., Fladmark, D., and Sheppard, J Metro Vancouver 2011 IMMPACT. Nuisance Mosquito Control Program. November Jackson, M. and McMahon, S Metro Vancouver 2012 IMMPACT. Nuisance Mosquito Control Program. November Jackson, M. and McMahon, S Metro Vancouver 2013 IMMPACT. Nuisance Mosquito Control Program. November Jackson, M. and McMahon, S Metro Vancouver 2014 IMMPACT. Nuisance Mosquito Control Program. November Jackson, M. and McMahon, S Metro Vancouver 2014 IMMPACT. Nuisance Mosquito Control Program. November

53 Jackson, M. and Patterson, K Metro Vancouver 2014 IMMPACT. Nuisance Mosquito Control Program. November Kaufman, M.G. and Fonseca, D.M Invasion biology of Aedes japonicus japonicus (Diptera: Culicidae). Annual Review of Entomology 59:31-49 Merritt, R. W., Lessard, J. L., Wessell, K. J., Hernandez, O., Berg, M. B., Wallace, J. R Lack of effects of Bacillus sphaericus (Vectolex ) on non-target organisms in a mosquito-control program in southeastern Wisconsin: a 3-year study. Journal of the American Mosquito Control Association. 21: Silver J Mosquito ecology: Field sampling methods third edition. Springer pp. Sjogren, R.D., Batzer, D.P., Juenemann, M.A Evaluation of methoprene, temephos and Bacillus thurigiensis var. israelensis against Coquillettidia perturbans larvae in Minnesota. Journal of the American Mosquito Control Association. 2: Wood, D.M., Dang, P. T., and Ellis, R The mosquitoes of Canada Diptera: Culicidae. 390pp. Agriculture Canada Publication 1686, Hull, PQ. 53

54 6.0 Appendices Appendix A: Township of Langley Surface Water Sites 54

55 Appendix B: Surrey Surface Water Sites 55

56 Appendix C: Maple Ridge Surface Water Sites 56

57 Appendix D: Pitt Meadows Surface Water Sites 57

58 Appendix E: Coquitlam Surface Water Sites 58

59 Appendix F: Langley Waste Water Treatment Plan Surface Water Sites 59

60 Appendix G: Mansonia perturbans Cattail Treatment Sites

61 Appendix H: Concern Call Locations

62 Appendix I: Facts about Mosquitoes Poster and Brochure for Public Education Events 62

63 63

64 Appendix J: Bookmark given out at Public Education Events 64

65 Appendix K: Fighter Biter Booklet given out at Public Education Events 65

66 66

67 67

68 68

69 69