Specifics Related to August Spraying Event
August 30, 2017
Deciding When to Spray
The Town’s West Nile Virus Integrated Management Policy follows a data driven approach to determine when spraying for adult mosquitoes should occur. Once the vector index, or risk level, reaches .5 or above, per Town policy, spraying is to commence town-wide. The risk level is not based on a single trap, but rather all the traps in the area which currently is four spread out in areas across the Town of Berthoud. West Nile virus positive mosquitoes were collected from three of the four trap locations in Berthoud this past week indicating a wide spread presence of the virus and infected mosquitoes based on the calculated VI of 1.1 by CSU testing labs for the Town
Product Used to Spray and Safety Issues
The Town of Berthoud contractor, VDCI, uses a product that is labeled and approved by the EPA and the State of Colorado for mosquito control purposes. They use this product at a higher dilution rate and an application rating far lower than the maximum amount allowed.
It is also important to note that there have been numerous, peer-reviewed, articles indicating that ULV applications for mosquito control do not pose a significant risk to humans or non-target insects. In one study (Effects of single and multiple applications of mosquito insecticides on non-target arthropods, Davis and Peterson, 2008), the researchers determined that “measurable and persistent biological effects on non-target arthropods, exposed to larvicides and adulticides applied via ULV sprayer would be small”. Also in an article published by the Center for Disease Control (Human Exposure to Mosquito-Control Pesticides — Mississippi, North Carolina, and Virginia, 2005), the researchers measured the pesticide metabolite concentrations in urine of people pre-and post- application. And it was determined that “ULV application in mosquito control activities did not result in substantial pesticide exposure to humans”. In contrast, they were able to show an “association between home and/or work application of pesticides and pesticide metabolite concentrations”. In other words, individuals are far more likely to have pesticide exposure from home and work related uses of pesticides than from ULV mosquito control efforts.
We understand that there is great concern about our mosquito control applications. For that reason, we take great measures to avoid deleterious effects from the pesticide. We use a very small dose, we spray when mosquitoes are most active but most people and non-target insects are not, we atomize the product to a very fine droplet (<20 microns) to reduce the amount of deposition and residue, we apply when meteorological conditions are most conducive to success and all of our equipment is routinely serviced and checked to ensure accuracy of the application.
One of the primary ways we reduce the risk of pesticide exposure to humans is with our low application rate. We apply AquaKontrol 30-30 at a rate of 0.0035 lbs of active ingredient per acre. In other words, for the average sized property in this neighborhood, approximately 0.00053 pounds (0.0085 ounces) of permethrin would be applied per property. For reference, typical head lice shampoos containing 1% permethrin are used for head lice treatment at a rate of 1-2 oz applied directly to a child’s scalp every 9 days.
Many of the human health concerns stemming from pesticide exposure are the result of the accumulation of persistent pesticides in the environment, from miss-applications or from applications of an entirely different kind. When used incorrectly, pesticides can indeed lead to cancer, leukemia and brain tumors. However, those reactions to mosquito control applications are not reported due to the lower percentage of concentrate, additional dilution of product that we do, and application methodology of our equipment.
We cannot eliminate all the risk of contracting WNV, just like we cannot eliminate all the risk of applying pesticide; the goal is to find the right balance and make people’s lives in the Berthoud community safer.
Larviciding at Loveland Reservoir
The majority of land around Loveland Reservoir is owned by the Town of Berthoud and VDCI does have access to the areas that produce larvae. Larvae tend to produce in the dense vegetation around the edge of the lake and in cattails that cover the north and western edge. VDCI has surveyed the southern part of the lake which is privately owned property but do not find production in that area.