Rossland, BC, V0G1Y0 - Columbia Shuswap Regional District Electoral Area 'A', Town of Golden Mosquito Control Program Mid-Season Update 7 July 2020
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Columbia Shuswap Regional District
Electoral Area ‘A’, Town of Golden
Mosquito Control Program
Mid-Season Update
7 July 2020
Submitted by:
Morrow BioScience Ltd.
2197 Columbia Avenue
Rossland, BC, V0G1Y0
Electoral Area ‘A’ and Town of Golden Mosquito Control Program Table of Contents LIST OF FIGURES .................................................................................................................................. III LIST OF APPENDICES .......................................................................................................................... III EXECUTIVE SUMMARY ......................................................................................................................... 1 INTRODUCTION...................................................................................................................................... 3 SIGNIFICANT REGIONAL ENVIRONMENTAL CONDITIONS ....................................................... 3 SNOW LEVELS ............................................................................................................................................................ 3 RIVER LEVELS ............................................................................................................................................................ 6 PRECIPITATION .......................................................................................................................................................... 9 AMBIENT TEMPERATURE RECORDS ................................................................................................................... 10 NUISANCE CONTROL ........................................................................................................................... 13 PROGRESS TO DATE ............................................................................................................................................... 13 GROUND APPLICATION SUMMARY ...................................................................................................................... 14 AERIAL APPLICATION SUMMARY ........................................................................................................................ 16 PUBLIC RELATIONS ............................................................................................................................. 17 ANNOYANCE REPORTS/INQUIRIES ..................................................................................................................... 17 EDUCATION OUTREACH ........................................................................................................................................ 18 PROJECT CONTACTS AT MORROW BIOSCIENCE LTD. ............................................................. 19 REFERENCES.......................................................................................................................................... 19 Morrow BioScience Ltd. ii
Electoral Area ‘A’ and Town of Golden Mosquito Control Program
List of Figures
Figure 1. 2020 river levels (m) recorded at the Columbia River at Donald gauge (ID:
08NB005), Columbia River at Nicholson gauge (ID: 08NA002), and the Kicking
Horse River at Golden gauge (ID: 08NA006) as reported by the River Forecast
Centre. 2020 data are current through 4 July ..................................................................... 7
Figure 2. 2017 - 2020 Columbia River at Donald gauge levels (m; ID: 08NB005), as
reported by the River Forecast Centre. 2020 data are current through 4 July..... 8
Figure 3. 2020 precipitation values (rainfall and snow accumulation; mm) recorded
at the Golden Airport weather station (ID: 1173210) for 01 April 1 – 2 July.
Average station precipitation values (1981-2010) are shown.................................. 10
Figure 4. Maximum daily ambient temperatures (C) as recorded at the Golden
Airport weather station (ID: 1173210) 01 April 1 – 2 July 2020. Lower black
line illustrates threshold at which Ae. sticticus eggs commence hatching; upper
black line illustrates threshold at which most Ae. sticticus eggs hatch. ................. 12
Figure 5. Ground application events (purple; ha) with Columbia River at Donald
(green; m) and Columbia River at Nicholson (blue; m). Data presented are from
1 April – 4 July 2020 ..................................................................................................................... 15
Figure 6. Aerial application events (black; ha) with Columbia River at Donald
(green; m) and Columbia River at Nicholson (blue; m). Data presented are from
1 April – 4 July 2020. .................................................................................................................... 17
List of Appendices
Appendix I. Mosquito biology and disease transmission FAQ document located at
morrowbioscience.com.
Appendix II. Aquabac® and Bacillus thuringiensis var. israelensis FAQ document
located at morrowbioscience.com.
Appendix III. Blog addressing mosquito disease transmission with specific
attention paid to COVID-19. Blog located at morrowbioscience.com.
Morrow BioScience Ltd. iii
Electoral Area ‘A’ and Town of Golden Mosquito Control Program Executive Summary The snowpack within the Upper Columbia Basin contributes run-off to the Columbia River and Kicking Horse River near Electoral Area ‘A’/Town of Golden. The 2020 snowpack was 113 percent of normal immediately prior to the mosquito season. Cooler-than-normal weather in April slowly brought out some low elevation snow from the Upper Columbia Basin. Provincial ambient averages were variable in May, with warmer weather in late May leading to regional snowmelt and a peak in the Kicking Horse River on 1 June (4.95 m). A secondary warming trend in the latter half of June caused mid and most high elevation snowmelt, resulting in local peaks of the Columbia River at Donald (28 June, 4.61 m) and Nicholson (30 June, 3.63 m). The Columbia River at Donald peak was considerably higher than those recorded in 2018 and 2019. As of 6 July, some high-elevation snow remained in the Upper Columbia Basin (i.e. ~9%). The regional Columbia River is receding, but may do so slowly until the regional snowpack is exhausted and notwithstanding significant precipitation. The local precipitation accumulation in April was lower-than-normal and likely did not contribute to the creation of mosquito development sites. However, local precipitation accumulation in May was higher-than-average and likely augmented the regional rivers. Environment Canada probabilistic weather forecasts show a 40-50 percent likelihood that precipitation accumulation will be above normal, with normal ambient temperatures forecasted within Area ‘A’/Golden from July-September. Thus, elevated regional river levels may persist longer-than-normal in 2020. Site monitoring began on 20 April and ground treatments commenced on 22 April at snowmelt mosquito development sites. Higher-than-normal river resulted in a need for seven aerial treatment campaigns in the program, thus far. Aerial and ground treatments were well-timed and effective, targeting variable larval development throughout the purview. A bacterial larvicide, AquabacÒ (active ingredient - Bacillus thuringiensis var israelensis) was used to treat approximately 2,910 ha (11,640 kg granules) required within Area ‘A’/Golden, as of 4 July. Few complaint calls or emails have been received as of 6 July. Six (6) calls and one email were received, with only two (2) calls classified as a complaint. All calls and emails were responded to within 24 hours of receipt. Call and email volume are expected to increase with warmer weather and as adult mosquitoes begin to disperse from peak river hatching events. Provincial recommendations against large gatherings in order to reduce the spread of COVID-19 resulted in adjusted education outreach strategies for 2020. MBL dispensed information on social media platforms and the MBL website. Two FAQ documents (i.e. mosquito biology and disease transmission FAQs, and Bacillus thuringiensis var. israelensis FAQs) were sent directly to the CSRD program manager Morrow BioScience Ltd. 1
Electoral Area ‘A’ and Town of Golden Mosquito Control Program in early May. Additionally, a disease transmission blog with focus on COVID-19 was posted on the MBL website. The head biologist was interviewed by a local radio station on 4 June to inform residents about the program, mosquito biology, and general mosquito control efforts being conducted within Area ‘A’/Golden. MBL will continue to update social media sites about program-specific activities throughout the height of the season. Morrow BioScience Ltd. 2
Electoral Area ‘A’ and Town of Golden Mosquito Control Program Introduction This report will include a summary of the mosquito control program activities for Area ‘A’ and Town of Golden within the Columbia Shuswap Regional District (CSRD) for the 2020 season through early July. Specifically, this report will include current environmental conditions affecting mosquito populations and monitoring efforts, outline the progress to date for the proposed deliverables, present any preliminary data, and identify potential issues for the duration of the mosquito season. The information presented herein is meant to provide a snapshot of the season, thus far. An in-depth review of each reporting category will be included in the 2020 final report, to be submitted by October. Significant Regional Environmental Conditions Snow Levels Floodwater mosquito control is the main focus of the Area ‘A’/Golden program. Snowmelt mosquito control is also conducted, but comprises a relatively small fraction of the overall control effort. Floodwater mosquito abundance within Area ‘A’/Golden is primarily governed by the regional Columbia River (i.e. Donald and Nicholson gauges) water levels. The Kicking Horse River also contributes water to the Columbia River near the Town of Golden, affecting down-stream flows. The water levels of those systems are mainly governed by the freshet released from the Upper Columbia Basin (Image 1). Frequent and large amounts of local precipitation can also affect river levels. However, in normal years, localized precipitation accumulation typically affects river levels to a lesser degree than the Basin – associated freshets during the late spring and early summer. Morrow BioScience Ltd. 3
Electoral Area ‘A’ and Town of Golden Mosquito Control Program
Image 1. Upper Columbia Snow Survey Basin (pink; https://www2.gov.bc.ca/gov/)
On 1 April 2020, immediately preceding the commencement of the mosquito larvae
monitoring season, the snowpack within the Upper Columbia Basin was 113 percent
of normal 1 . Predominantly weak systems were recorded in April, but ambient
temperatures within the Upper Columbia Basin were cooler-than-normal. Generally,
the snowpack in this basin increased slightly during April2. This trend is observed in
the Colpitti Creek weather station (ID: 2A30P) data (Image 2). The Colpitti Creek
station is the closest weather station to Area ‘A’/Golden and largely representative of
other weather stations in the vicinity.
The first measurable melting trend occurred in mid-May, with the middle and some
high-elevation snow showing significant drops in Snow Water Equivalent (SWE). The
Colpitti Creek snow weather station is a high-elevation station that shows a
decreasing snowpack during this timeframe (Image 2). This melting trend shows that,
while there was considerable snow melt in mid-May, the snowpack was augmented
slightly at various points in May due to multiple low-pressure systems. A more
1 https://www2.gov.bc.ca/assets/gov/environment/air-land-water/water/river-forecast/2020_apr1.pdf
2 https://www2.gov.bc.ca/assets/gov/environment/air-land-water/water/river-forecast/2020_may1.pdf
Morrow BioScience Ltd. 4Electoral Area ‘A’ and Town of Golden Mosquito Control Program consistent warming event began at the end of May3. This warming trend resulted in the melting of most low and mid-elevation snowpack. Cooler weather occurred in the first half of June slowing the snow melt in the Upper Columbia Basin. However, ambient temperatures within the Basin in the second half of June brought out much of the high-elevation snowpack. The final River Forecast Centre (RFC) Snow Survey and Water Supply Bulletin (15 June) reported that Upper Columbia Basin snowpack was 162 percent of normal4. The RFC notes that the percentages reported in the 15 June report should be interpreted cautiously. The relatively high snowpack currently noted in comparison to the typically low snowpack at this point in the season may provide a misleading extreme gauge on the remaining snowpack. However, the data do indicate the rarity of residual snowpack at this point in the season. Despite warming weather in the Upper Columbia Basin through late May and into early July, there was still some remaining snow as of 6 July (Image 2). Image 2. Colpitti Creek weather station (ID: 2A30P) Snow Water Equivalent trends (Upper Columbia Basin, 6 July 2020; BC Snow Survey Data Centre). Continued warming trends have further depleted snowpacks in the Upper Columbia Basin since the most recent Snow Survey and Water Supply Bulletin update (15 June). Automated Snow Weather Station data relays real-time Snow Water Equivalent (SWE) remaining at specific stations within each basin. The number of stations (i.e. six) within this basin is not high nor spatially representative of the basin, so the level of inference about basin-wide snowpack is high. As of 6 June, an estimated 9 percent of the SWE was left in the Upper Columbia Basin. With forecasted increasing 3 https://www2.gov.bc.ca/assets/gov/environment/air-land-water/water/river-forecast/2020_june1.pdf 4 https://www2.gov.bc.ca/assets/gov/environment/air-land-water/water/river-forecast/2020_june15_v10.pdf Morrow BioScience Ltd. 5
Electoral Area ‘A’ and Town of Golden Mosquito Control Program temperatures for early July within those regions, it is likely that the SWE will be entirely depleted by the middle of July. As such, the Columbia River and Kicking Horse River levels may remain slightly elevated until the snowpacks are exhausted. River Levels Floodwater mosquito eggs are laid on the damp substrate of areas that experience intra-annual flooding. Within Area ‘A’/Golden, floodwater mosquito development sites primarily exist along the flooding corridor of the Columbia River (Nicholson gauge, ID: 08NA002; Donald gauge, ID: 08NB005), including associated seepage sites. The Kicking Horse River at Golden also contributes to the Columbia River, affecting the Donald gauge levels. The presence of water is a hatching cue and, thus, tracking regional river levels provides predictive capabilities with regards to floodwater mosquito larval development. Within the mountain bench areas, mosquito development sites are primarily snowmelt associated. Mosquito eggs are laid in previous seasons within ditches and small depressions. Those areas collect snow or run-off from local snowmelt. When ambient temperatures begin to rise in the early spring, snowmelt mosquito eggs are able to hatch in those typically ephemeral mosquito development sites. In late-April 2020, a pulse of water came through local rivers from the Upper Columbia Basin (Image 2). That pulse marked the consistent rise of the regional Columbia River and Kicking Horse River (Figure 1). The first measurable warming trend occurred within the Upper Columbia Basin in early May, resulting in considerable freshet collection in the regional Columbia River and Kicking Horse River. Variable warming and cooling stints occurred through mid-June, resulting in fluctuating freshet input to those Rivers. During this period, the Columbia River at Donald exceeded the point at which ground treatments in that area typically become necessary (black line; Figure 1). The Kicking Horse River at Golden peaked on 1 June (4.952 m) following a short, but significant warming stint during that period. The Columbia River at Donald and Nicholson wouldn’t peak, however, until nearly a month later. A basin-wide warming trend in occurred in late-June, melting mid-elevation snow and most of the high-elevation snowpack from the Upper Columbia Basin. Following suit, the Columbia River at Donald peaked on 28 June at 4.613 m and the Columbia River at Nicholson peaked on 30 June at 3.632 m (Figure 1). Because the majority of the contributing snowpack has been depleted (see ‘Snow Levels’ above), it is unlikely that the peaks, thus far, will be surpassed. Morrow BioScience Ltd. 6
Electoral Area ‘A’ and Town of Golden Mosquito Control Program
2020 Columbia River and Kicking Horse Levels
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Figure 1. 2020 river levels (m) recorded at the Columbia River at Donald gauge (ID: 08NB005), Columbia
River at Nicholson gauge (ID: 08NA002), and the Kicking Horse River at Golden gauge (ID: 08NA006) as
reported by the River Forecast Centre. 2020 data are current through 4 July. Black line denotes Columbia
River (Donald gauge) when associated mosquito development sites historically require treatment.
The Area ‘A’/Golden mosquito control program is disparately affected by the
Columbia River due, primarily, to the input from the Kicking Horse River influencing
the Donald gauge levels. The Columbia River at Nicholson portion of the program is
treated sooner if the snow comes off sub-basins contributing primarily to the
Columbia River, while the Columbia River at Donald is treated sooner if the snow
comes off sub-basins contributing primarily to the Kicking Horse River. It is
important to track all noted river levels intra-annually to best determine treatment
needs. However, the Columbia River at Donald gauge provides a broader perspective
for inter-annual regional freshet comparisons.
The 2020 Columbia River peak at Donald hasn’t been this high since 2017 (Figure 2).
It was approximately 0.73 m higher than the 2019 peak and 0.19 m higher than the
Morrow BioScience Ltd. 7Electoral Area ‘A’ and Town of Golden Mosquito Control Program
2018 peak (Figure 2). As opposed to 2019, all mosquito development sites in Area
‘A’/Golden were wet at peak Columbia River levels in 2020.
Columbia River Levels (2017-2020)
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2017 2018 2019 2020
Figure 2. 2017 - 2020 Columbia River at Donald gauge levels (m; ID: 08NB005), as reported by the River
Forecast Centre. 2020 data are current through 4 July.
The current year’s peak in the Columbia River (Donald gauge) relative to those of
recent seasons’ is another predictive variable that may help explain a current year’s
mosquito larval abundance. If the current year’s peak river level far exceeded those
of the preceding seasons’, mosquito eggs laid between the high-water mark of those
years could have remained dormant until current-year flood waters trigger their
hatching. Because the peak of the Columbia River in 2020 far exceeded those of 2019
and 2018, it is likely that the peak level noted in 2020 triggered a considerable
number of eggs laid in the preceding lower-water years to hatch. As such, a higher-
than-normal larval abundance has been noted thus far and is expected through the
remainder of the 2020 season.
Another predictive variable for determining larval mosquito abundance for
floodwater mosquitoes is the rate at which rivers rise. Mosquito eggs laid on
substrates at various river levels have optimal environmental conditions and
adequate time within which to hatch when rivers rise at a slower rate. When levels
rise at high rates, mosquito eggs typically lack sufficient environmental cues to hatch
due to the pulse of cold, highly oxygenated water moving through the system. The
regional Columbia River and Kicking Horse River rose at moderate rates in 2020 due
to the relatively slow melt of the contributing snowpack. The slow snow melt coupled
with inconsistent weather meant that high Columbia River levels have also been
Morrow BioScience Ltd. 8Electoral Area ‘A’ and Town of Golden Mosquito Control Program sustained longer than normal. Thus, environmental cues were present to trigger mass mosquito hatching events at near-peak river levels. The Columbia River is slowly receding, given little remaining snowpack at high elevation snow stations (see ‘Snow Levels’ above). However, the Columbia River peaks at both the Donald and Nicholson gauges occurred approximately 3 weeks later than normal. Thus, declining levels may also take longer than normal to reach pre- flood stage. Besides residual high-elevation snowpack, local precipitation accumulation can considerably augment regional river levels (see ‘Precipitation’ below) at this point in the season. The long-term forecast does include a high likelihood of greater-than- normal precipitation. If significant precipitation occurs again, then that will likely sustain local river levels and associated seepage sites at unseasonably high levels. Precipitation While not the primary contributor to the Columbia River or Kicking Horse River levels within Area ‘A’/Golden, significant and concentrated local precipitation accumulation may temporarily elevate river levels, lending to the creation or augmentation of mosquito development sites. The precipitation received at the Golden Airport weather station (ID: 1173220) in April was approximately 8 mm lower than the station average (1981-2010; Figure 3). It is likely that precipitation did not measurably augment local river levels or mosquito development sites in April. In contrast, May precipitation accumulation in 2020 exceeded the station average by approximately 5 mm (Figure 3). While not significantly higher than average, the local precipitation received in May was on top of the rising freshet. Thus, in smaller systems like the Kicking Horse River, it is likely that the timing and amount of precipitation received in May augmented levels and likely led to the increased area of mosquito development sites near northern reaches of the program. Precipitation received to the area in June was lower-than-average (Figure 3). While lower than average, the over-all amount and timing of the events (i.e. 26-28 June) were such that peak Columbia River levels at Donald and Nicholson were likely slightly augmented by local precipitation. The Golden Airport weather station is current through 2 July. Thus, the precipitation accumulation noted in July is artificially low for this point in the year. Temperature and Precipitation Probabilistic Forecasts for Canada5 for July – September show a 40- 50% likelihood that precipitation for Area ‘A’/Golden will be above normal. Given this prediction, it is possible that significant precipitation events will occur in July, prolonging the presence of the mosquito development seepage sites. MBL technicians 5 https://weather.gc.ca/saisons/prob_e.html Morrow BioScience Ltd. 9
Electoral Area ‘A’ and Town of Golden Mosquito Control Program
are aware of the potential development of new sites given localized precipitation
events and will continue to monitor current and potential sites.
60
Monthly Precipitation Accumulation
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Precipitation (mm)
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20
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0
April May June July August
Average (1981-2010) 2020
Figure 3. 2020 precipitation values (rainfall and snow accumulation; mm) recorded at the Golden Airport
weather station (ID: 1173210) for 01 April 1 – 2 July (blue). Average station precipitation values (1981-
2010) are shown in orange.
Ambient Temperature Records
Ambient temperature, both locally and within the contributing snow basin, is an
important environmental condition to track. Ambient temperature data provides
information specific to the freshet timing, floodwater mosquito larval development,
and potential adult dispersal. The 2020 mosquito season began in April with below-
normal ambient temperatures across most of the snow basin contributing to the
regional Columbia River and Kicking Horse River. According to the May 1st Snow
Survey and Water Supply Bulletin6, the weather in April was largely stable, with only
a few weak systems presenting throughout southern BC. Below-average ambient
temperatures within the Upper Columbia Basin through April meant that the freshet
and associated floodwater mosquito development within Area ‘A’/Golden were
delayed by 2-3 weeks (Figure 4). Brief periods of warming temperatures in April
melted snow in the Upper Columbia basin and contributed relatively little to the
regional Columbia River and Kicking Horse River.
6 https://www2.gov.bc.ca/assets/gov/environment/air-land-water/water/river-forecast/2020_may1.pdf
Morrow BioScience Ltd. 10Electoral Area ‘A’ and Town of Golden Mosquito Control Program In general, ambient temperatures in early May were also lower-than-normal. However, a ridge of high pressure in mid and late-May aided in the increased melting rate of low and some mid-elevation snowpack. Ambient temperatures in contributing basins and locally dropped in early June. However, ambient temperatures increased in the second half of June. Ultimately, this increase in ambient temperatures in late June would lead to the regional Columbia River peaks in 2020. Temperature data is consistent with 2020 automated snow station data 7 depicting snowmelt points correlating with regional ambient temperature spikes. Local ambient temperatures can be a predictive tool in understanding when floodwater eggs might begin to hatch. In a laboratory experiment, Trpis and Horsfall (1969) exposed submerged eggs of a common univoltine floodwater mosquito species, Aedes sticticus, to various constant air temperatures and recorded hatching success. Results revealed that eggs began to hatch at 8°C, although larval development was slow and survivorship was low. Eggs held at 21°C provided the optimal temperature, of the five temperatures tested, for hatching and larval development (Figure 4). While Ae. sticticus is not the sole floodwater species present in BC, the species serves as a representative one for our purposes and provides general developmental benchmarks. It should be noted that extrapolating laboratory results to the field is not always necessarily appropriate due to the considerable additional variables for hatching success in the field (e.g. natural predators, water depth, associated water temperature, organic matter, etc.). Thus, the benchmark noted here is meant to provide a conservative gauge for the commencement of mosquito larval monitoring and treatment. 7 https://www2.gov.bc.ca/gov/content/environment/air-land-water/water/water-science-data/water-data-tools/snow- survey-data/automated-snow-weather-station-data Morrow BioScience Ltd. 11
Electoral Area ‘A’ and Town of Golden Mosquito Control Program
2020 Daily Maximum Ambient Temperature
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Threshold: greatest mosquito egg hatching
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Ambient Temperature (C)
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Threshold: mosquito egg hatching commencement
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Figure 4. Maximum daily ambient temperatures (C) as recorded at the Golden Airport weather station (ID:
1173210) 01 April 1 – 2 July 2020. Lower black line illustrates threshold at which Ae. sticticus eggs
commence hatching; upper black line illustrates threshold at which most Ae. sticticus eggs hatch.
Locally, the 2020 season also began with lower-than-normal ambient temperatures
for April. However, given that mid-April temperatures were above those noted as
being sufficient for mosquito egg hatching, floodwater mosquito eggs within Area
‘A’/Golden area were likely activated within April if exposed to flooding conditions
(Figure 4). The larval development at cooler temperatures would have been notably
slow (Trpis and Horsfall 1969). The potential for larval development – even in the
early portion of the mosquito season – is the primary reason for site monitoring
commencement in April.
Snowmelt mosquito eggs along the Columbia River bench area were also likely
triggered to hatch in April as sites began to show initial melting. These species
typically hatch early to ensure their development habitat remains wet from hatching
to emergence and also to reduce inter-species habitat competition as they develop
(Clements 1992). Certain snowmelt mosquito species begin to hatch at approximately
4°C water temperature and can complete development to adult emergence at 10°C
(Clements 1992).
Local ambient temperatures in later May and into June were relatively warmer and
closer to the most favourable larval development conditions for floodwater
mosquitoes (Figure 4). Thus, it was expected that hatching and larval development
rates would increase significantly within those months. Appropriately, larval
treatments also increased significantly in the beginning of May when a spike in
Morrow BioScience Ltd. 12Electoral Area ‘A’ and Town of Golden Mosquito Control Program ambient temperature warmed mosquito development sites to more favourable hatching conditions (Figure 4). Temperature and Precipitation Probabilistic Forecasts for Canada 8 for July – September do not show a significant likelihood that ambient temperatures for Area ‘A’/Golden are going to be different than normal. The normal trend is for ambient conditions to become warmer through July and then start to decrease in mid-August. Warming conditions into July will increase snow melt in high-elevation basins, present favourable environmental conditions for mosquito hatching, and increase the rate of development for mosquitoes. Increasing temperatures with relatively less precipitation means that mosquito development sites may become dry in August. Nuisance Control Progress to Date Seasonal mosquito development site monitoring begins when spring ambient temperatures start to rise steadily in the Upper Columbia Basin, followed by consistently increasing regional Columbia River and Kicking Horse River levels. Consequently, the 2020 mosquito-monitoring season started in mid-April as the Columbia River and Kicking Horse River levels were just beginning to increase above winter levels. 8 https://weather.gc.ca/saisons/prob_e.html Morrow BioScience Ltd. 13
Electoral Area ‘A’ and Town of Golden Mosquito Control Program
The slight increase in ambient
temperatures in mid-April led
to melting of some low
elevation snow within the
Upper Columbia Basin. This
early increase in ambient
temperature and pulse of water
in the system was sufficient to
activate mosquito eggs in a few
snowmelt mosquito
development sites. However,
ambient temperatures
remained low enough to delay
larval development into later-
April.
Mid-May temperatures slowly
increased across much of BC,
melting the remaining low-
elevation and some mid-
elevation snowpack in the
Upper Columbia Basin. The
snowmelt events, along with
Image 3. MBL staff member applying granular treatments via
higher-than-normal localized backpack blower to mosquito development sites.
precipitation accumulation in
May, caused regional Columbia River and Kicking Horse River levels to increase
beyond normal. Locally, early May daily ambient temperatures also consistently
reached the temperature threshold for optimal egg hatching and larval development
(Figure 4). A secondary warming trend in mid-June led to the peak of the Columbia
River at Donald and Nicholson in late June. The higher-than-normal peaks and
prolonged freshet in 2020 resulted in an increased need for ground treatment events
and aerial treatment events from April through June (Image 3). As of 6 July, a total of
approximately 2,910 ha have been treated in Area ‘A’/Golden.
Ground Application Summary
MBL field staff monitored mosquito development sites starting on 20 April in Area
‘A’/Golden. The Columbia River bench snowmelt mosquito development sites were
first treated on 22 April (Figure 5). Additional treatments quickly became necessary
following the initial treatment due to consistently increasing Columbia River and
Kicking Horse River levels (Figure 5). As opposed to 2019, all known sites were wet
this season.
Sites within Area ‘A’/Golden were visited on a weekly basis unless conditions
required more frequent monitoring (i.e. significantly high regional river levels,
Morrow BioScience Ltd. 14Electoral Area ‘A’ and Town of Golden Mosquito Control Program
ambient temperatures > 20°C, large precipitation events). Sites are treated when a
standard dip (350ml) collects 5 or more late instar (3rd or 4th instar) larvae per dip.
All sites are checked within one or two days of the initial treatment to ensure
treatment efficacy. If necessary, touch-up treatments are conducted.
AquabacÒ is the product used for all larval mosquito treatments conducted by MBL.
The active ingredient in AquabacÒ is a soil-borne bacterium, Bacillus thuringiensis
var. israelensis (Bti). Bti has high target specificity and achieves 95% - 100% efficacy
in typical field conditions (AquabacÒ Mosquito Biolarvicice - Technical Bulletin). The
application rate for ground treatments can vary depending on the plant density in the
target area. Using the granular product by ground, most sites in Area ‘A’/Golden
require an application rate of 4 kg/ha. The total area treated by ground within Area
‘A’/Golden as of 6 July was approximately 98 ha, which equates to about 393 kg of
granular Bti (Figs 5, 6). Real-time data associated with each treatment is available
through MBL’s client-registered, real-time program portal.
2020 River Levels and Ground Treatments
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Ground Treatments Columbia River (Donald) Columbia River (Nicholson)
Figure 5. Ground application events (purple; ha) with Columbia River at Donald (green; m) and Columbia
River at Nicholson (blue; m). Data presented are from 1 April – 4 July 2020. Treatment areas are
represented on the secondary y-axis.
Morrow BioScience Ltd. 15Electoral Area ‘A’ and Town of Golden Mosquito Control Program Aerial Application Summary The 2020 mosquito season is considered an above-normal water year. In high-water years, the aerial application portion of the Area ‘A’/Golden program becomes more important because field staff encounter site access challenges, as well as concurrent site activation. While many of the mosquito development sites within the program are accessible by ground, certain sites along the Columbia River require additional aerial treatments in high-water years. The number of aerial applications required are directly proportional to the height of the water and how long peak levels are sustained: low-water years require fewer treatments than high-water years. Considerably more floodwater larval mosquitoes were documented at sites in 2020 than in 2018 and 2019. The relatively high larval abundance is likely a function of higher water levels activating a compounded number of eggs laid above the 2018 and 2019 peak levels. The high water, coupled by the likelihood that more dormant mosquito eggs were activated due to the previous years’ low water, have made seven aerial treatments necessary as of 6 July. The aerial treatments occurred between 8 and 2 July (Figure 6). The 8 May aerial treatment event focused on treating large-scale snowmelt mosquito development habitat on the mountain benches. With regards to the floodwater treatments, aerial campaigns ideally take place immediately after the regional Columbia River has peaked because AquabacÒ (i.e. Bti) is able to reach mosquito larvae before they disperse with rising water. Mosquito development habitat proximate to the Columbia River at Donald and the Columbia River at Nicholson become active at different times due to the contribution of the Kicking Horse River near Golden. The aerial campaigns conducted in the Area ‘A’/Golden were perfectly timed to target the greatest abundance of mosquito larvae within each region of the program and in the most concentrated space (Figure 6). All treatments successfully controlled targeted snowmelt and floodwater mosquito larvae. Shapefiles of aerial treatments are maintained by MBL and will be supplied to the CSRD. Aerial application rates vary between sites due to differences in site canopy cover. Where canopy cover is greater, a higher granular application rate between 4 and 8 kg/ha may be necessary. This year, application rates were applied at 4 kg/ha. A total of 2,812 ha has been aerially treated, as of 4 July. This treatment area amounts to a total of approximately 11,248 kg of granular AquabacÒ (i.e. Bti) (Figure 6). Morrow BioScience Ltd. 16
Electoral Area ‘A’ and Town of Golden Mosquito Control Program
2020 River Levels and Aerial Treatments
5 800
700
4
600
Primary River Level (m)
Treatment Area (ha)
500
3
400
2
300
200
1
100
0 0
01-Jul
08-Jul
15-Jul
22-Jul
29-Jul
05-Aug
12-Aug
19-Aug
26-Aug
06-May
13-May
20-May
27-May
03-Jun
10-Jun
17-Jun
24-Jun
01-Apr
08-Apr
15-Apr
22-Apr
29-Apr
Aerial Treatments Columbia River (Donald) Columbia River (Nicholson)
Figure 6. Aerial application events (black; ha) with Columbia River at Donald (green; m) and Columbia
River at Nicholson (blue; m). Data presented are from 1 April – 4 July 2020. Treatment area is represented
on the secondary y-axis.
Public Relations
Annoyance Reports/Inquiries
MBL has maintained a Mosquito Hotline for over a decade (1-877-986-3363).
Messages left on the MBL Hotline are checked daily and recorded in a database. MBL
also has a contact form on the MBL website (morrowbioscience.com) that is directed
to staff inboxes. All calls and emails are returned within 24 hours
As of 6 July, six (6) calls and one (1) email have been received to the Mosquito
Hotline/MBL email contact form from the Area ‘A’/Golden program purview. Of the
calls, only two (2) were classified as complaints. The other four (4) were inquiries
about the purview extent, season forecast, and an early-season reminder to treat a
specific property. For a high-water year, the call and email volume to date has been
exceptionally low. However, the volume is expected to increase with the warming
weather and as adult mosquitoes disperse from peak Columbia River levels.
Morrow BioScience Ltd. 17Electoral Area ‘A’ and Town of Golden Mosquito Control Program Education Outreach Education outreach is a key aspect to each of MBL’s mosquito programs. The goals for this portion of the program are to increase awareness about personal protective measures, mosquito habitat reductive tips, and also to assure residents that Area ‘A’/Golden contractors are committed to mosquito control in their area. Outreach material can be presented in numerous forms: in person, through media interviews, and via social media sites. For the 9th year in a row, MBL has maintained a presence on social media. MBL has a Facebook account (facebook.com/MorrowMosquito), Twitter account (@MorrowMosquito), and Instagram account (linked to Facebook) which are regularly updated. Each platform includes posts regarding where monitoring events are taking place, what the environmental conditions are, and general larval abundance. As of 2 July 2020, the MBL Facebook page was up to 326 followers, which is an increase of 20 followers since this time in 2019. As of 2 July, the highest reach for a post most relevant to the Area ‘A’/Golden mosquito control program occurred on 24 June. The post described the higher-than-average mosquito annoyance as a direct result of high and sustained freshet levels, as well as cooler temperatures throughout most areas in southern BC. The post also provided personal protective tips for the longer-than-expected mosquito season this year. Given the provincial restrictions placed on large gatherings to reduce the spread of COVID-19, MBL has enacted a company-wide policy to invest in virtually-available education outreach material instead of attending public events. As such, the Morrow BioScience website (www.morrowbioscience.com) has highlighted two sets of FAQs focused on (1) mosquito biology and disease transmission (Appendix I) and (2) the active ingredient used in control efforts (Bacillus thuringiensis var. israelensis) (Appendix II). Additionally, a blog dedicated specifically to mosquitoes and COVID-19 was published on the MBL website (Appendix III). A media release was generated and approved by the CSRD program manager for distribution to radio stations with a reach within Area ‘A’/Golden. On 4 June, 104.3 FM EZRock conducted an interview with MBL’s head biologist. The interview included an update on general mosquito control activities occurring within the program purview. It also focused on tips to reduce mosquito breeding habitat around private properties and suggestions related to personal protective measures against mosquitoes. No additional interview requests have been made as of 2 July. If opportunities arise, MBL staff will ensure that the CSRD mosquito program manager is consulted prior to agreeing to an interview. Every effort will be made to accommodate interviews which assist in raising awareness about mosquito control efforts and personal protective measures. Morrow BioScience Ltd. 18
Electoral Area ‘A’ and Town of Golden Mosquito Control Program
Project Contacts at Morrow BioScience Ltd.
Dirk Lewis
Owner/Biologist
dirk@morrowbioscience.com
604.317.1413
Jeff Jackson
Program Operations Manager
Jeff@morrowbioscience.com
250.272.1168
Morgan Sternberg
Research Manager
morgan@morrowbioscience.com
250.231.4455
Barry McLane
GIS Manager
barry@morrowbioscience.com
250.231-6934
References
Becker Microbial Products, Inc. Aquabac Mosquito Biolarvicide – Technical Bulletin.
Accessed 12 June 2019. Available online:
https://beckermicrobialproductsinc.com/PDF/bulletin.pdf
Clements, A. (1992). Biology of Mosquitoes. CAB International.
https://beckassets.blob.core.windows.net/product/readingsample/457488/9
783540928737_excerpt_001.pdf
Trpis, M. and Horsfall, W.R. (1969). Development of Aedes sticticus (Meigen)) in
Relation to Temperature, Diet, Density, Depth. Annals Zoologici Fennici, 6(2):
156-160.
Morrow BioScience Ltd. 19CSRD – 2020 MID-SEASON REPORT
APPENDIX I
Frequently Asked Questions
Floodwater Mosquito Biology
and Disease Transmission
Updated: 3 May 2020Updated: 3 May 2020
Table of Contents
CATEGORY 1: MOSQUITO ECOLOGY ..................................................................................................... 3
QUESTION 1: WHAT TYPE OF MOSQUITOES ARE CONTROLLED BY MORROW BIOSCIENCE LTD (MBL)? ....................... 3
QUESTION 2: WHY DOESN’T MBL CONTROL CONTAINER MOSQUITOES LIKE THOSE IN RESIDENTIAL BACKYARDS AND
CATCH BASINS? ............................................................................................................................................ 3
QUESTION 3: WHAT CONDITIONS NEED TO BE PRESENT FOR FLOODWATER MOSQUITOES TO HATCH? ........................ 3
QUESTION 4: WHAT ENVIRONMENTAL FACTORS IN BC GOVERN FLOODWATER MOSQUITO DEVELOPMENT? ................ 3
QUESTION 5: WHY ARE ADULT MOSQUITOES MOST ABUNDANT AFTER THE PEAK IN LOCAL RIVERS? ........................... 4
CATEGORY 2: MOSQUITO DEVELOPMENT ............................................................................................ 5
QUESTION 1: WHAT IS THE LIFECYCLE OF FLOODWATER MOSQUITO SPECIES WITHIN THE PROGRAM AREA? ................. 5
QUESTION 2: AT WHAT LIFE STAGE ARE MOSQUITOES TARGETED FOR CONTROL? .................................................... 5
QUESTION 3: HOW FAR CAN MOSQUITOES FLY FROM THEIR HATCH SITE? .............................................................. 6
CATEGORY 3: DISEASE TRANSMISSION ................................................................................................ 6
QUESTION 1: WHAT DISEASES CAN MOSQUITOES TRANSMIT IN CANADA? ............................................................. 6
QUESTION 2: IS WEST NILE VIRUS A CONCERN IN BC? WHAT ARE THE MOST RECENT LEVELS? .................................. 6
QUESTION 3: WHERE CAN I GO TO FIND MORE INFORMATION ABOUT WEST NILE VIRUS?......................................... 7
QUESTION 4: CAN MOSQUITOES ACT AS A VECTOR FOR COVID-19? .................................................................... 7
QUESTION 5: WHERE CAN I GO TO LEARN MORE ABOUT POTENTIAL VECTORIZATION OF COVID-19 IN MOSQUITOES? .. 7
REFERENCES ......................................................................................................................................... 8
2Updated: 3 May 2020
Category 1: Mosquito Ecology
Question 1: What type of mosquitoes are controlled by Morrow BioScience Ltd (MBL)?
Most mosquito control program operated by MBL focus on one complex of mosquitoes, those that
develop in floodwaters, primarily during the Spring freshet (e.g. Aedes vexans, Aedes sticticus).
However, certain programs within BC also have snowmelt mosquito species (e.g. Aedes
communis). The females of these snowmelt species lay eggs in depressions within the landscape
that allow for snowmelt or precipitation to accumulate. Eggs are able to hatch under considerably
cooler conditions than those of floodwater or container mosquito species. At this time, MBL does
not control mosquito species typically found in containers (e.g. Culex pipiens).
Question 2: Why doesn’t MBL control container mosquitoes like those in residential
backyards and catch basins?
At this time, MBL doesn’t focus on treating containers (i.e. catch basins, bird baths, gutters, old
tires, etc.) to control container mosquito species primarily because besides catch basin habitats,
most of the container mosquito development sites are located on private property. While
sometimes producing enough mosquitoes to create very localized annoyance, they don’t create
broader nuisance levels. Although MBL doesn’t specifically target container mosquitoes, field and
outreach staff have developed messaging aimed at informing residents of proactive measures
that can reduce container mosquito habitat around their homes. Measures include refreshing
stagnant water daily during the height of the season, ensuring gutters are cleaned and not
holding water, removing old tires, covering rain barrels with a fine mesh to prevent mosquitoes
from accessing, and many more.
Question 3: What conditions need to be present for floodwater mosquitoes to hatch?
Floodwater mosquito eggs are triggered to hatch when submerged by fresh floodwaters, typically
occurring as a result of the Spring freshet in BC. As water warms up in the late spring, larvae
develop faster.
Question 4: What environmental factors in BC govern floodwater mosquito
development?
Tracking environmental factors that affect the flooding capacity within an area are important.
Flooding in BC typically occurs in the Spring as a result of the Spring freshet from snow basins
contributing to local rivers. Snowpacks vary inter-annually. When snowpacks in contributing
basins are low, the freshet usually follows suit and when they are high, the freshet is
comparatively high. A high freshet means more mosquito eggs may be activated to hatch,
3Updated: 3 May 2020
especially if previous seasons’ freshets resulted in low local river levels. Snowpacks in BC are
assessed by automated snow weather stations throughout the year and can be found at:
https://www2.gov.bc.ca/gov/content/environment/air-land-water/water/water-science-
data/water-data-tools/snow-survey-data.
Significant temporally and spatially concentrated precipitation accumulation may also elevate
local river levels. Local precipitation can temporarily increase seepage site levels, where
considerable mosquito development habitat is located. Thus, tracking local precipitation
accumulation can aid MBL field staff with determining how long mosquito development sites may
require management. Local weather station data can be found at: https://climate.weather.gc.ca
Question 5: Why are adult mosquitoes most abundant after the peak in local rivers?
Peak river levels represent the time at which the majority of floodwater mosquito eggs have been
triggered to hatch for the season. The time from when an egg hatches to emergence and dispersal
is typically 2-3 weeks (although this is highly dependent upon water temperatures). So even as
local river levels are receding, mosquito development may still be taking place. Adult floodwater
mosquitoes are strong enough to disperse from their hatch site quickly and are able to fly multiple
kilometers in search of a blood meal. Significantly warm weather increases the rate at which a
mosquito develops and may lead to more aggressive activity toward the end of a mosquito’s
lifespan.
4Updated: 3 May 2020
Category 2: Mosquito Development
Question 1: What is the lifecycle of floodwater mosquito species within the program area?
Source: North Shore Mosquito Abatement District (https://www.nsmad.com)
Floodwater mosquito eggs are laid in the damp substrate along floodwater corridors. Flooding
along with other appropriate environmental triggers (i.e. sufficiently warm, low dissolved oxygen)
allow for the eggs to hatch into larvae. The larvae go through four aquatic instar stages, which
are also the primary feeding stages, prior to developing into pupae (i.e. non-feeding stage). Pupae
then emerge into adults. The development process can take as little as four days in some species
to as long as two weeks. Development times also depend on ambient and aquatic temperature,
with warmer water resulting in accelerated mosquito development.
Question 2: At what life stage are mosquitoes targeted for control?
MBL does not conduct adult mosquito control. Adult control requires the use of pesticides with
considerable indirect and non-target effects. Instead, MBL targets the larval stage of the
mosquito. Mosquito larvae are the feeding stage of the life cycle, which makes the larval instars
particularly susceptible to larvicides dependent on ingestion. Specifically, the 3rd and early 4th
5Updated: 3 May 2020
larval instars are the target of MBL’s floodwater mosquito control program. The feeding rate
increases within the 3rd and early 4th instar stages, making the larvicide more effective.
Additionally, the 1st and 2nd instar larval stages are left as biomass in the aquatic ecosystem to
support the food web. This strategy helps with limiting the frequency of treatments and
supporting as robust a food web as possible.
Question 3: How far can mosquitoes fly from their hatch site?
Maximum flight distance from hatch site varies widely dependent upon species. A common
floodwater, Aedes vexans, may fly greater than 4 km from their hatch site, on average. The main
implication of these data is that uncontrolled mosquitoes may impact people from distances
farther than 4 km, in some circumstances. MBL endeavours to reduce mosquito annoyance to
residents in all areas within the contract purview.
Category 3: Disease Transmission
Question 1: What diseases can mosquitoes transmit in Canada?
In Canada, mosquitoes have been shown to transmit West Nile virus, Eastern Equine encephalitis
virus, and California serogroup viruses. West Nile virus is the most widely distributed vector borne
disease in North America. As the climate in Canada becomes warmer, the environment is more
hospitable to additional vectors and associated viruses.
Question 2: Is West Nile virus a concern in BC? What are the most recent levels?
West Nile virus (WNv) is only a slight concern in BC given the relatively few number mosquito
pools, birds, horses, and humans who have tested positive. From 1 January – 12 October 2019,
one positive human WNv case was detected in BC. In that same year no animals, no mosquito
pools, and no birds tested positive for the virus. Certain container mosquitoes, such as Culex
pipiens and Culex tarsalis, are primary WNv vectors. Thus, in years and situations where container
mosquito breeding is more prolific (i.e. warmer weather), more WNv transmissions may occur.
To reduce WNv exposure through mosquitoes, MBL and the BC Centre for Disease Control urges
residents to:
• remove or refresh standing water daily in the warmer months,
• ensure that outdoor plants or containers have a drainage hole,
• clear rain gutters of debris and make sure they drain,
• turn over wading pools when not in use, and
• install screens on windows and doors.
6Updated: 3 May 2020
Question 3: Where can I go to find more information about West Nile virus?
Health Canada maintains a thorough surveillance website, delineating cases by type (i.e.
human, animal, mosquito), week, and province from mid-April through October. The Health
Canada site also provides health-specific information surrounding WNv. It can be found at:
https://www.canada.ca/en/public-health/services/diseases/west-nile-virus.html
The BC Centre for Disease Control (BCCDC) website also contains health-related information for
residents. The BCCDC site has a more detailed map of surveillance activity by region. It can be
found at: http://www.bccdc.ca/health-info/diseases-conditions/west-nile-virus-wnv
Question 4: Can mosquitoes act as a vector for COVID-19?
At this time, there is no evidence that mosquitoes are involved in the spread of COVID-19 (SARS-
CoV-2). It is thought that the COVID-19 virus may not survive the internal processes of the
mosquito. Other supportive evidence for the inability of mosquitoes to act as vectors COVID-19 is
that other Coronaviruses have not proven transmissible through mosquitoes.
Question 5: Where can I go to learn more about potential vectorization of COVID-19 in
mosquitoes?
The Center for Disease Control addresses the potential for vectorization of COVID-19 in
mosquitoes: https://www.cdc.gov/coronavirus/2019-ncov/faq.html
The World Health Organization also addresses this question:
https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/myth-
busters
7Updated: 3 May 2020
References
Belton, P. (1983). The Mosquitoes of British Columbia. British Columbia Provincial Museum,
Victoria, British Columbia, Canada.
Center for Disease Control. (2020). Coronavirus Disease 2019 (COVID-19), Frequently Asked
Questions. Available online: https://www.cdc.gov/coronavirus/2019-ncov/faq.html
Health Canada. (2018). West Nile Virus and Other Mosquito-Borne Diseases National
Surveillance Report. Available online: https://www.canada.ca/en/public-
health/services/diseases/west-nile-virus/west-nile-virus-other-mosquito-borne-
disease.html
Trpis, M. and Horsfall, W.R. (1969). Development of Aedes sticticus (Meigen)) in Relation to
Temperature, Diet, Density, Depth. Annals Zoologici Fennici, 6(2): 156-160.
Verdonschot, P. F.M. and Besse-Lotoskaya, A. A. (2014). Flight Distance of Mosquitoes
(Culicidae): A Metadata Analysis to Support the Management of Barrier Zones Around
Rewetted and Newly Constructed Wetlands. Limnologica 45 (2014): 69-79.
Wood, D.M., Dang, P.T., and Ellis, R.A. (1979). The Insects and Arachnids of Canada (Part 6).
Ottawa, Canada.
World Health Organization. (2020). Coronavirus Disease (COVID-19) Advice for the Public: Myth
Busters. Available online: https://www.who.int/emergencies/diseases/novel-coronavirus-
2019/advice-for-public/myth-busters
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