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CANYON COUNTY MOSQUITO ABATEMENT DISTRICT

9719 Booker Lane

Nampa, Idaho 83686

Phone – (208) 461-8633

Fax – (208) 461-4459 Members: IMVCA, ECA of Idaho,

 NWMVCA, AMCA 

 Establish

 MOSQUITO AND PESTICIDE USE PLAN

 DEER FLAT NATIONAL WILDLIFE REFUGE, LAKE LOWELL SECTOR

 For 2010

 Introduction

The Canyon County Mosquito Abatement District has for eleven years been managing

the mosquito population around the Lake Lowell Sector of DFNWR. The presence of

Western Equine Encephalitis (WEE) was detected in cattle on ranch property that borders

the south boundary of the refuge in 1999. Active arbovirus surveillance in the adult

mosquito population was initiated in 2000. In 2006 there was a West Nile Virus outbreak

in Idaho. Lake Lowell Sector accounted for 40% of the positive West Nile pools detected

and tested in Canyon County during the 2006 epidemic. In 2007 there was no arbovirus

activity detected in the adult mosquito population on DFNWR. The main reasons for this

were two fold: 1.) Intensified larvicide activity in 2006. 2.) 2007 was a low water year

for the reservoir. However Canyon County did have 30 positive WNV pool site

locations. This was the most in the state and more than three quarters of the states nation

wide. In 2008 mosquito activity on DFNWR was again limited by low water volumes in

Lake Lowell and no positive Arbovirus was detected. In 2009, water levels on DFNWR

were at the highest level in over five years and many areas that had been dry became

flooded. As a result of these high water levels in, the Western Equine Encephalitis

mosquito (Culex tarsalis) spiked early in the year and positive West Nile Virus was first

detected on June 24.
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Deer Flat National Wildlife Refuge Surveillance Data 2009

0

200

400

600

800

1000

1200

1400

5/26/2009

6/2/2009

6/9/2009

6/16/2009

6/23/2009

6/30/2009

7/7/2009

7/14/2009

7/21/2009

7/28/2009

8/4/2009

8/11/2009

8/18/2009

8/25/2009

9/1/2009

Trapping Date

Trapped Mosquito numbers

Cx t

Cx p

Ae vx

Ochl n.

An free

Cu in.

2009 Surveillance date for DFNWR shows an early spike in the population of Culex tarsalis (BLUE) with positive WNV

activity first detected on June 24, 2009.
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 DFNWR 2009 SURVEILLANCE DATA

Date Species

Cx t Cx p Ae vx Ochl n. An free Cu in. Total

26-May 591 4 161 53 36 23 868

8-Jun 1086 16 61 19 220 179 1581

17-Jun 530 17 0 27 20 76 670

24-Jun 1195 65 3 6 117 196 1582

1-Jul 509 55 43 4 33 34 678

8-Jul 641 20 4 1 288 135 1089

14-Jul 671 78 27 4 116 123 1019

22-Jul 122 60 14 22 74 13 305

1-Aug 165 137 111 2 0 0 415

6-Aug 106 80 4 0 198 7 395

18-Aug 67 24 0 1 54 6 152

24-Aug 61 14 3 1 80 5 164

4-Sep 23 0 0 0 34 0 57

5767 570 431 140 1270 797 8975

Above surveillance data chart shows spike in Western Equine Encephalitis Mosquito (Culex tarsalis) . The numbers in red

indicate positive West Nile virus mosquito activity.

 Species Identification Key

 Cx t.............Western Equine Encephalitis Mosquito (Culex tarsalis)

 Cx p.............Northern House Mosquito (Culex pipiens)

 Ae vx............Inland Flood Water Mosquito (Aedes vexans)

 Ochl n..........Irrigated Pasture Mosquito (Ochlerotatus nigromaculis)

 An free..........Western Malaria Mosquito (Anopheles freebornii)

 Cu in............Winter Marsh Mosquito (Culiseta inornata)

 CCMAD Integrated Pest Management Principles (I.P.M) for DFNWR

I.P.M is a decision making process that uses all available pest management strategies.

This process will help determine what method of control will reduce the mosquito

populations to an acceptable level with the least impact to the environment. I.P.M.

methods will also weigh the health risk to exposure to pesticides versus the health risk of

an arbovirus.

CCMAD-I.P.M. will identify the following strategies for management of mosquito

populations: (The explanations of IPM strategies are found starting on page 2 of the

CCMAD Comprehensive Mosquito Management Plan that accompanies this document.)

1. Education.

2. Cultural.

3. Mechanical.

4. Biological.

5. Chemical or Pesticide use.

6. Surveillance.

7. Action Thresholds.

 

 Adult Mosquito Monitoring and Surveillance
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DFNWR is part of the Lake Lowell Control Sector of CCMAD and is the main source of

mosquito populations for this Sector. Mosquito surveillance is conducted for the

following reasons:

1. Adult mosquito population dynamics.

2. Species identification.

3. Presence of a mosquito borne disease.

4. Determining Action thresholds.

CCMAD conducts adult mosquito surveillance by deploying CDC CO2 light baited traps

throughout areas of DFNWR. A map of trap deployment is included with this document.

Traps are set out two times a week staring in May or sooner depending on weather

conditions. Eight to ten traps are deployed per night.

West Nile Virus Testing: Mosquitoes trapped are frozen and identified by species and

cataloged. Mosquitoes prepared for testing are divided into testing pools of 50 and tested

for West Nile Virus using the R.A.M.P. (Rapid Analytical Measurement Platform)

system. The R.A.M.P. system allows for accurate and immediate field testing for West

Nile Virus and allows for timely management decisions. Positive mosquito pools are

communicated with the Idaho Department of Health and Welfare Bureau of Laboratories.

Management decisions to determine action threshold levels are determined by a

calculated minimum infection rate of West Nile Virus tested mosquitoes. A calculated

M.I.R (minimum infection) is determined by the use of the following formula:

 Total # of positive tested pools x 1000 = M.I.R

 Total # of mosquitoes trapped

As defined by the Center for Disease Control, a calculated M.I.R of 5 mosquitoes / 1000

may indicate epidemic levels. The M.I.R ratio of 5/1000 is used by Idaho Public Health

Officials as a bench mark number to take emergency action such as region wide aerial

adulticide treatments.

 Pesticide Use and Action Level Thresholds

To determine pesticide use on DFNWR larval surveillance is first conducted. Larval

surveillance locations are noted on the included maps with this document.

Larval Control Action Thresholds: Thresholds are determined by standard mosquito

dipping techniques. Dipping is done in open water, along banks, under vegetation,

flooded areas, standing water pools that are shallow, catch basins and shoreline habitat.

Density determinations for Culex species (primary disease vectors):

 Low: 1-5 larvae per dip.

 Medium: 6-10 larvae per dip.

 High: > than 10 larvae per dip.
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The larvae density action level can be used to determine low much larval control products

are to be use or even if any action is to be taken. The following is the Action Level

Threshold that CCMAD takes on DFNWR:

 Low population density: No action taken.

 Medium population density: Use 5-7 lbs. per acre of Bti.

 High population density: Use 7-10 lbs. per acre of Bti.

Pesticides Used: Currently only biological control agents are used on DFNWR with the

active ingredient Bacillus thuringiensis israelensis.

Bti Agents used:

• Vectobac 12 AS aqueous suspension. EPA reg. no 73049-38

• Vectobac CG granular formulation. EPA reg. no. 73049-19

• Tecknar CG granular formulation. EPA reg. no. 73049-403

• Aquabac xt aqueous suspension. EPA reg. no. 62637-1

Pesticide Methods of Application:

1. Bti liquid products are applied by backpack sprayer or hydraulic power spray

equipment if large areas are treated.

2. Bti granular products are applied by hand granular spreaders and backpack power

blowers. In areas of limited access by ground or large acreage areas, fixed wing

aircraft are used.

Adulticide applications:

At the present time there are no immediate plans to use adulticide materials on

DFNWR. To review adulticide application methods and pesticide use refer to

CCMAD Comprehensive Mosquito Management Plan submitted with this

document.

CCMAD currently uses two mosquito adulticide materials within the district to control

adult mosquito populations:

• Malathion ULV, brand name: Fyfanon ULV EPA Reg. No. 67760-34

• Permithrin ULV, brand names: BioMist 4+4 EPA Reg. No. 8329-35

 Kontrol 4-4 EPA Reg. No. 53883-118

Contingency Emergency Mosquito Adulticide Plan:

When M.I.R. numbers reach epidemic levels, CCMAD will submit an emergency

adulticide use plan. Any consideration of adulticide materials will be to reduce the

infection rate of vector born species such as Culex species for West Nile Virus.
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This use plan will involve the use of truck mounted U.L.V. equipment to apply a targeted

adulticide application to areas that have elevated M.I.R of 5/1000 and elevated Culex

species numbers. This plan will occur over a short period of time (one or two nights).

Mosquito population will be monitored and again tested for disease presence. Materials

to be used will be from the above list. The total acreage to be treated will be of that that

is accessible by ground equipment and not to exceed 1,185 acres. (This figure was

computed by mileage measurements of access roads and multiplied by a 300 ft. swath

U.L.V. delivery swath.) Emergency adulticide applications will be considered when

threat level matrix (USFWS suggested matrix) reaches level 6 or level 7. (See proposed

threat level matrix below.)

 

 Health Threat Determinations

The following agencies are involved with determining a Health Threat emergency in

Canyon County:

1. The Board of County Commissioners. Amended Idaho Statutes (2007) 39-2812

p.1 states that the Board of County Commissioners are authorized to declare a

pest or vermin a “Public Health Threat”. In 2008 Canyon County was in the

second year of a declared emergency by the Board of County Commissioners.

This Public Health threat created the Canyon Interim Mosquito District for areas

that were not under the jurisdiction of the Canyon County Mosquito Abatement

District. An election in November 2008 made the interim district permanent and

has merged with CCMAD to create a county wide mosquito control program.

2. Mosquito Abatement Districts. Through field data and mosquito populations

monitoring, Canyon County Mosquito Abatement District plays an important role

in Health Threat determinations. CCMAD communicates its’ field findings with

the Idaho State Department of Health and Welfare and Central District Health

Department.

3. Idaho State Department of Health and Welfare. The Bureau of Laboratories may

be charged with confirmation of positive mosquito testing pools. The BOL

mostly relies on field testing data from Mosquito Abatement Districts.

4. Southwest District Health. The primary responsibility of Southwest District

Health is to monitor the disease outbreak potential and disseminate information to

the public the potential risks of a mosquito borne disease outbreak and

preventative measure to take.

Arbovirus History of DFNWR:

In 1999 cattle on ranch property that is adjacent to the southern boundary of DFNWR on

Lakeshore Dr. tested positive for Western Equine Encephalitis. In 2006 mosquitoes

testing positive for West Nile Virus were discovered early in June. The first confirmed

Culex tarsalis pools occurred on June 6 followed by positive pool discovery dates of June
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14, 20, 28, July 11, 17, 24, August 15 and 22. In total in 2006 there were 22 positive

West Nile Virus pools located on DFNWR Lake Lowell Sector. This was over _ of the

total for the County in the epidemic year of 2006. The total cumulative Minimum

Infection Rate for DFNWR (M.I.R.) was 12.04/1000. As mentioned earlier in this report

the bench mark for taking emergency action is the ratio of 5 infected mosquitoes/1000.

In 2007 there were no positive West Nile Virus mosquitoes pools detected on DFNWR.

County wide there were however thirty positive pools detected. In 2008 there was no

positive West Nile Virus mosquito activity detected from CCMAD surveillance on Deer

Flat National Wildlife Refuge. In 2009, West Nile Virus was detected on 5 sites with 5

infected traps. The M.I.R. in 2009 never approached the 5/1000 bench mark.

Arbovirus vector mosquito species detected:

Three primary vectors for West Nile Virus and Western Equine Encephalitis have been

identified on DFNWR.

• Culex tarsalis: Common name- Western Encephalitis Mosquito. This

species made up over 90% of the primary West Nile Virus vector species.

• Culex pipiens: Common name-Northern House Mosquito. Of lesser

importance but a very efficient transmitter of West Nile Virus.

• Culex erythrothorax: Common name-Tulle Mosquito. Populations of this

mosquito fluctuate greatly from year to year. It is an efficient transmitter

of West Nile Virus especially in bird populations.

 Mosquito Borne Threat Level Matrix

The State of Idaho in 2007 Revised West Nile Virus Phased Response Guidance for

Counties has defined five levels of response which is included with this document.

The USFWS included a Threat Matrix table in their Draft CFR and CCMAD used this

matrix in 2008 and 2009. CCMAD will adapt this matrix response again in 2009.

Health Threat Matrix (USFWS Draft CFR):

Health Threat Cat. Action Level Threat Level Response

_______________________________________________________________________________________

No documented or No action 1 Remove or manage breeding sites.

historical health threat

Documented historical Below action

Health threat. threshold. 2 Respond as in level 1, also allow surveillance.

 Above Action

threshold. 3 Response as in level 1&2 also allow site

 specific larvicide applications

Documented existing

Health Threat Below Action

 Thresholds. 4 Response as in threat level 2 plus increase

monitoring and disease surveillance.
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 Above action

 Thresholds. 5 Response as in level 3 & 4 plus allow site

 specific larvicide, pupacide or adulticide.

High risk for mosquito

 borne disease. Below action

 threshold. 6 Maximize monitoring and disease

surveillance.

 Above action

 Thresholds. 7 Response as in threat level 6 plus allow sitespecific applications of larvicide, pupacide

 and adulticide.

________________________________________________________________________________________________

In 2009 there were 5 positive mosquito pools on 5 different sites. With continued high water

levels and high water level carry over into 2010, CCMAD will begin the DFNWR mosquito

year at Matrix Level 4 using the above Matrix threat level for DFNWR.

 CCMAD Mosquito Management Strategy for Deer Flat National Wildlife Refuge

In 2009, CCMAD will deploy 10 to 12 surveillance traps in DFNWR. These traps will

be analyzed weekly and mosquitoes will be tested for WNV and other arbovirus diseases.

Below is an arbovirus surveillance trap location map for 2010.
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Larval inspections will begin as weather dictates in the spring and large scale larvicide

operations will again be conducted with contract aerial applicator, Valley Air Service

from Caldwell, Idaho. USFWS will be contacted before any aerial larvicide applications

are performed with information as to where the application will be conducted and how

may acres and rate of application of Bti.

Below is the record for Larvicide operations for 2009 on DFNWR. CCMAD speculates

that larvicide operations in 2010 should be similar to 2009.
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* Response to Positive West Nile Virus surveillance activity .

 

Application 

Date

Rate Acres 

Treated

Location Amount 

Used

May 1 8 

lbs/acre

500 acres DFR Access 2

to Access 8

4000 lbs.

May 19 8 

lbs/acre

200 acres N. Y. Canal inflow to DFR 

Access 1 and Access 8 (lower 

embankment dam to DFR 

Access 5

1600 lbs.

June 5 8 

lbs/acre

300 acres Gott’s Point to N.Y. Canal 

inflow

2400 lbs.

June 17 8 

lbs/acre

200 acres Gott’s Point to N.Y. Canal 

inflow

1600 lbs.

June 26* 8 

lbs/acre

200 acres Access 0 to Access 6 1600 lbs.

June 29* 8 

lbs/acre

200 acres Access 0 to Access 6 1600 lbs.

July 17* 8 

lbs/acre

180 acres Tio Lane Access to Access 1 1440 lbs.

July 28* 10 

lbs/acre

220 acres DFR Marsh 

DFR Access 8 (lower 

embankment dam) to Access 6

2200 lbs.

TOTALS 2000 acres 

treated

14,240 lbs. 

of Bti 

applied.

Arbovirus Disease Forecast for 2010:

Blue line: Currant level Green line: 2009 level Red line: Average level
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Current Data Graph

PROVISIONAL DATA - SUBJECT TO C HANGE!

Accessibility

• Water levels of Lake Lowell for the beginning of 2010 Water Year are at above

average levels and a History of elevated vector populations.

• Disease levels (West Nile Virus) were at highest level since 2006 epidemic year.

• In 2009 DFNWR accounted for 36% of the WNV tested mosquito pools county

wide.

• In 2009 DFNWR accounted for 27% of total positive West Nile virus pools

Respectfully Submitted,

Ed Burnett, Director of Operations