Over Wynwood, the Miami neighborhood where Zika gained a foothold in the continental United States, low flying planes have been spraying naled, a tightly controlled pesticide often used as a last resort. It appears to be working, killing at least 90% of the target mosquitoes, Reuters reports. 

 

Across the Biscayne Bay in Miami Beach, wind and high-rise buildings make aerial spraying challenging. So, the effort in the popular tourist destination has focused on ground-sprayed pyrethroids - pesticides that are safer but don't always work. The arrival in Florida of Zika, a virus that can cause a crippling birth defect known as microcephaly, has drawn into focus the limitations of the U.S. mosquito control arsenal. Larvicides reduce future populations relatively safely. But for use against the mature mosquitoes that spread disease, only two classes of pesticides are approved. Each has drawbacks. Organophosphates, such as naled, are effective. But there are strict controls to limit risk. Pyrethroids are safer but have been used so much that mosquitoes, in many places, are immune.

 

"That's really the weak link in much of the United States," said Michael Doyle, director of the Florida Keys Mosquito Control District. "We're kind of caught off guard."

 

Doyle led a 2009 effort against a dengue outbreak in South Florida, the first in the United States in nearly a century. Authorities threw everything they had at the Aedes aegypti, the same mosquito that carries Zika: backpack fogging, door-to-door yard inspections looking for watery breeding sites and larvicide spraying.

 

Still, 88 people were infected before the virus was brought under control more than two years later, and there continue to be sporadic cases in Florida. The outbreak highlighted gaps in the mosquito control arsenal that remain, according to pesticide makers, abatement officials and entomologists. Few companies make pesticides for use in public health outbreaks, a niche market that is expensive to get into, has a limited upside and varies season to season.

 

Safety testing a new pesticide can cost up to $250 million and take 10 years, said Karen Larson, vice president of regulatory affairs at privately held Clarke Mosquito. As long as a product remains on the market, companies must continue testing for unforeseen side effects, an expense that some makers have blamed for decisions to abandon products.

 

"There's not a lot of profit," Larson said. Sales of the Dibrome brand of naled have been estimated at $12 million a year. By comparison, total crop pesticide sales for some companies can exceed $500 million in a single quarter. Bayer, Dow Chemical(DOW.N), BASF (BASFn.DE) and other agricultural pesticide makers "are not interested in going after a $20 million or $30 million a year market," said William A. Kuser, investor relations director at Dibrome maker American Vanguard Corp (AVD.N).

 

The U.S. Environmental Protection Agency has approved several new pesticides in recent years. But it has received few requests for using them against mosquitoes, said Jim Jones, Assistant Administrator for the agency's Office of Chemical Safety and Pollution Prevention.

 

"Although it's of critical importance, the amount one can sell is small and it's variable, which makes it difficult for business planning," Jones said. "You can go many years without having much of a market at all, then suddenly, whether it's because of a nuisance outbreak of mosquitoes or something like West Nile or Zika, the market grows significantly."

 

Abatement authorities have pressed for help with the cost of developing mosquito control pesticides. The 1996 U.S. Food Quality Protection Act includes a provision for subsidies to defray the expense of safety testing, but Congress has never funded it.

 

Photo: Reuters

Нашли ошибку в тексте? Выделите её мышкой и нажмите: Ctrl + Enter



Related

Comments