| This is the first edition of
a newsletter focusing on managing public mosquito control programs in
South Dakota. It is being sent to coordinators of the SD Dept of Health
Mosquito Control grant funds. It will also be available at http://sdces.sdstate.edu/westnile/community.htm
Please see that the other communities involved with your grant are aware
of this information. If you know of information or have experiences you
would like to share with other mosquito managers, please forward the information
to me at Wilson.james@ces.sdstate.edu
or (605) 688-4752 and we will consider it for future issues.
Information from Hands-On Mosquito Control
During the last two weeks of June approximately 75 individuals attended
the hands-on mosquito control workshops offered by the Extension Service.
There have been requests for some of the information that was presented,
so I am sending copies of some of the material and providing Internet
links of other information. Please see that this material is filed in
your “West Nile Virus – Reference for South Dakota”
notebook and that a copy gets circulated to the individuals who are actively
involved in your public m mosquito control program.
Adult Mosquito Surveillance – Internet Graphing program
Many communities have been active in trapping and counting mosquitoes
on a regular basis to estimate populations and determine if adult spraying
is necessary. To assist you in evaluating your mosquito counts and comparing
your counts with neighboring communities, the Extension Service is inviting
you to enter your data into a web-based graphing program. The public viewing
page is located at: http://www.ces.sdstate.edu/mosqcount/
From this page select a county (click within its borders) to see if any
communities have reported their trap counts. Try selecting Yankton county
then select “Yankton M.Mag.” You should see a graph listing
their total mosquito count and the number of culex tarsalis If you are
interested in using this data graphing program to enter your mosquito
counts, please contact Jim Wilson by phone ( 605 688-4752) or by email
(wilson.james@ces.sdstate.edu)
and I will enter your name and trap locations into the program.
Mosquito Identification
One of the easiest mosquito ID keys was put together by Dr. Mike Hildreth,
SDSU and is available online at: http://biomicro.sdstate.edu/Hildrethm/Mosquito/Index.html
Then click on “Identification Procedures” to become familiar
with the terminology of the mosquito parts. From there click on “South
Dakota Adult Mosquito Key”. The left picture shows a male mosquito.
If you find your sample is not a male, you will likely need to click on
the far right picture. This should take you to pictures of mosquitoes
with pointed butts and those with rounded butts. Since most of the mosquitoes
you will catch will likely be either Aedes vexan or Culex tarsalis, this
will separate the two most likely groups. If the mosquito has a pointed
butt, it is probably an Aedes vexan. If it has a rounded butt, it is probably
a Culex tarsalis. If you think it may be a Culex tarsalis, click on the
“rounded butt” pictures then click on the lower left picture
“culex species” and note if it has a light colored band part
way down it’s snout (proboscis). A rounded butt and a light band
on the proboscis is a good indicator that you have a Culex tarsalis.
Microscopes are almost a necessity for identifying mosquitoes unless you
have a good hand lens and very good eyes. You may want to consider visiting
with your local school to see if they may have one you could borrow. Be
sure you check the type of microscope that is available. Ideally you should
look for a “dissecting” microscope that includes a magnification
of 10X – 60X. . You should have a light source from above, not below
the mosquito. Many of the microscopes in biology labs may be “slide”
microscopes. They generally have a much greater power (more than 60X)
and provide light from the bottom. Some communities have used an Intel®
PlayTM QX3TM Computer Microscope http://www.intel.com/intelplay/
for around $55 on the Internet. This microscope plugs into a computer.
It doesn’t not have the best picture, but it may be suitable.
You may want to keep track of the numbers of mosquitoes using the example
surveillance form that is enclosed. Also enclosed is a copy of a set of
suggested threshold guidelines developed by SDSU, SD Department of Health
and Sioux Falls Health Department to assist you in determining when to
consider adult mosquito control. These are suggestions only. Your threshold
may be different.
Pesticide Application Records / Emergency Discharge Response Plan
South Dakota Department of Agriculture requires that every commercial
pesticide applicator must complete applicator records at the close of
each business day. This includes those certified in the public health
category, that are either applying an adulticide or a larvicide. The specific
record requirements are available at http://www.state.sd.us/doa/das/pestrule.htm#records
We have enclosed an example form, approved by SD Dept of Ag, that may
be suitable for mosquito application records.
All commercial applicators are also required to have an emergency discharge
response plan on file. Extension Extra 8109 – Handling Pesticide
Properly (enclosed) will provide you with a simple example plan and an
explanation of what to include in your plan. SD Department of Ag have
a more comprehensive plan available to download at http://www.state.sd.us/doa/das/Com_resp.pdf
Adulticide Applications
Many questions have surfaced regarding when and how often to spray for
adult mosquitoes. In order for ULV applications to work, mosquitoes must
be actively flying and come in contact with a droplet of spray. This means
that spraying should start no earlier than dusk. This may be 9 or 9:30
p.m. in some communities. If you are spraying in the mornings you will
want to finish spraying around sunrise. By spraying at these times you
are getting the most cost effective control and you also reduce the exposure
to people who may be walking, or biking. Some communities avoid spraying
at these times because of the cost of overtime for employees. They may
find that the money spent for extra sprayings may be much more than the
cost of overtime for spraying at the best time.
When to spray adult mosquitoes should be based on surveillance data such
as trap counts and not by using a schedule. If you spray every Tuesday
but get a rebound in the population by Friday you may miss the peak population
and increase your community’s risk of WNV infections. By the same
token, if you are spraying twice a week and there are no significant mosquito
populations you are wasting money and exposing individuals to the pesticide
with no benefits. It’s kind of like shooting a shotgun in the air
twice a week and hoping a duck may be flying by. You will waste a lot
of shells and probably not get many ducks. Scout (light traps), evaluate
your data (see on-line graphing above), and determine if the numbers meet
the threshold before you spray. Not only is this the most cost effective
method, it will give you documentation for answering the calls about why
you did or did not spray on a certain day.
Don’t forget to take every opportunity to educate the public. If
the public understands why you are doing something they will be more likely
to accept it. Mosquito control and WNV Information is available at your
local Extension Office. Also don’t forget to notify the public before
you intend to spray. Local radio, newspapers, and local cable TV public
access channels .are some of the most common method. Some smaller towns
are using different ideas such as, the marquee sign on the local bank,
sign boards on main street, and posting notices in front of the post office.
If people aren’t “surprised” by the adulticide application,
they will be less likely to complain. If you find people on the sidewalk
when you are spraying, consider stopping until they pass. Avoid treating
ball diamonds, parks, or other public areas when people are present.
Also remember that larviciding should be continued even after you have
started adult spraying. It will help keep the populations from rebounding
quickly. If you have questions or comments, please let us know. |
