(Beyond Pesticides, September 2, 2016) Last Sunday, beekeepers in Dorchester County, South Carolina emerged from their homes to find their yards and farms, once full of busy buzzing, littered with the honey bees. The cause was no mystery — a massive bee-kill had occurred due to aerial spraying of Naled, a highly toxic insecticide used primarily to control adult mosquitoes. The county announced plans to spray two days before the incident, when four travel-related cases of Zika virus were confirmed in the area by the state Department of Health and Environmental Control. The spraying occurred between 6:30 and 8:30am.
Naled is an organophosphate insecticide with the highest acute toxicity of any mosquitocide. According to the Environmental Protection Agency (EPA), Naled can cause cholinesterase (an enzyme necessary to the transmission of nerve impulses) inhibition in humans, meaning that it can overstimulate the nervous system causing nausea, dizziness, confusion, and, at very high exposures (e.g., accidents or major spills), respiratory paralysis and death. Naled is highly toxic to honey bees.
In Dorchester County, beekeepers say that the spray announcements did not come soon enough. Flowertown Bee Farm and Supply lost more than 2.3 million insects from 46 hives, according to co-owner Juanita Stanley. “Had I known, I would have been camping on the steps doing whatever I had to do screaming, ”˜No you can’t do this,’” Ms. Stanley said in an interview with Charleston’s WCSC-TV. Ms. Stanley told the Post and Courier that the bees are her income, but that “it’s not about the honey, it’s about saving the bees.” Andrew Macke, a hobby beekeeper, had two hives that he had been caring for over two years. After the plane flew over, releasing the toxic insecticide onto their property, Mr. Macke’s wife called him to tell him about the “thousands and thousands of bees dead” all around their pool deck and driveway.
The county acknowledged the bee deaths Tuesday. “Dorchester County is aware that some beekeepers in the area that were sprayed on Sunday lost their beehives,” Jason Ward, county administrator, said in a news release. He added, according to the Post and Courier, “I am not pleased that so many bees were killed.” Unfortunately, this doesn’t alleviate the devastation that occurred, nor does it repay the financial loss that some of the beekeepers now face.
Ms. Stanley worried about how to move forward from the incident. “I don’t know where to go from here,” Ms. Stanley said to the Post and Courier. “I can’t just go out and buy more bees, and right now I’m focused on how do I clean up all this mess? What can be reused and what can’t? What steps do I take?” This can be tricky, as the impacts of mosquito spraying on pollinators can be felt long after spraying has ended. Pesticide residues on vegetation, surface waters, soil and hives, which can last from several hours to months after application, results in continued exposure for non-target organisms.
While counties and mosquito abatement districts across the country gear up to prevent the spread of Zika virus, it is prudent to keep in mind that while mosquito management is a necessary public health service, common methods of control —aerial and ground spraying of pesticides— not only have questionable efficacy, but can also harm non-target organisms like pollinators, whose populations are already suffering elevated losses. In this particular case, the four documented cases of Zika virus that triggered the aerial spray were all travel-related. At the time of spraying, there were no known mosquitoes in the area that were carrying the Zika virus, which means that the spraying did not serve to alleviate a public health risk. With the continuous news coverage on the threat of Zika, many communities are quick to react, despite the fact that there are no mosquitoes in the area that are infected with the virus. Given the potential health risks and environmental impacts of adulticiding, spraying purely to control nuisance mosquitoes should be avoided.
While we do not underestimate the threat from new and current mosquito-borne diseases, an ideal mosquito management strategy adopts an integrated approach that emphasizes education, aggressive removal of breeding sites (such as standing water), larval control, monitoring, and surveillance. Alternative strategies, including introducing mosquito-eating fish, encouraging predators, such as bats, birds, dragonflies, and frogs, and using least-toxic larvicides, like Bacillus thuringiensis (Bt), can be applied successfully without endangering pollinators and other organisms.
Widespread spraying is not a solution for these mosquito-borne diseases. These methods fail to sufficiently control mosquito populations, promote pesticide resistance, and kill other species that act as natural predators to mosquitoes. In our attempts to stave off these diseases, we inadvertently harm ourselves, non-target organisms and overall ecosystem biodiversity. We can protect pollinators and manage mosquito populations at the same time. A measured approach is needed for managing mosquitoes that first involves an understanding of the mosquito’s lifecycle, reducing breeding sites, and targeting larval populations. Control of disease-carrying mosquitoes that does not endanger pollinators can be successful when emphasis is placed on public education and preventive strategies.
Individuals can take action by eliminating standing water, using least-toxic mosquito repellents, and talking to neighbors about alternatives. We have created the Mosquito Doorknob Hanger, which has great tips on speaking with neighbors on backyard and community mosquito control. Community based programs should encourage residents to employ these effective techniques, focus on eliminating breeding sites on public lands, and promote monitoring and action levels in order to determine what, where, and when control measures might be needed.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.