To avoid overusing chemical agents in the war against West Nile virus, the city of Plano has enlisted a small aquatic army to prey on mosquito larvae.
Known as “mosquitofish,” the city has introduced the fish by the hundreds into local bodies of water, hoping to build a thriving population to combat mosquitoes before they reach adulthood.
“They will eat other things, but if there’s mosquito larvae, they will tend to pick that over anything else,” said Joseph Daley, Plano’s stormwater program administrator. “So it’s kind of like eating your dessert — for them, anyway.”
Introducing mosquitofish into local bodies of water such as Rowlett Creek, White Rock Creek and Spring Creek is more effective than using larvicides — chemicals that kill mosquito larvae — which are better suited for stagnant ponds, Daley said.
“One of the end goals is for us to use less chemicals,” Daley said. “The idea and the hope is that by using larvicides and the fish, by getting the populations of mosquitoes under control, we don’t have to use [adulticide sprays] as often.”
Dr. James Kennedy, regents’ professor of biology at the University of North Texas, has done work advising local governments and other organizations on ways to prevent the spread of West Nile. He has recommended the use of mosquitofish as one component of a balanced approach.
“Although there is a place for adulticides and control of adult mosquitoes, it’s a very, very tricky business at that point,” Kennedy said.
“If you can control those larval populations, you’re far ahead of the game in terms of controlling mosquito populations.”
Predator and prey
The mosquitofish, also known by its scientific name, Gambusia affinis, or simply gambusia, has a biological advantage over other native fish when it comes to capturing mosquito larvae, Kennedy said.
“Other fish that eat insects may take mosquito larvae, but the advantage of the gambusia is their mouthparts are directed upwards so they are able to take the larvae at the surface of the water, so they are very effective predators of that kind of insect,” he said.
The city of Plano bought about 500 mosquitofish from a fish farm in Arizona, but some local vendors such as Water Gardens Galore in Dallas sell them, often for use in private ponds.
Barbara Moeller, who co-owns Water Gardens Galore with her son, Steven Moeller, said she has been selling the fish since she started her business about 20 years ago. During that time, sales have remained steady, she said.
“Maybe a little bit more people [are] asking about them the last two or three years, but I think that’s because people are more concerned about West Nile,” she said.
A growing demand
Depending on the size of the individual fish, which can range from roughly four to seven centimeters in length, Moeller sells them for 25 to 50 cents per fish.
One of Moeller’s customers, Dallas resident Joyce Mills, said she stocked her backyard pond with mosquitofish when she removed its aerators and filters. The fish helped fight mosquito larvae in the newly stagnant water.
Since then, Mills said, there are virtually no mosquitoes in her yard.
“I’m from Illinois originally, right on the Mississippi, and we too were never able to go out at night the mosquitoes were so bad,” Mills said. “It’s so pleasant to be able to go out there and sit and talk and enjoy the evenings and mornings.”
Daily hopes the fish continue to multiply to the point where the species becomes self-perpetuating, helping to keep the mosquito problem under control. But until then, the city will continue periodically introducing more fish to bodies of water.
And success, he said, will ultimately be measured by its effect on minimizing the mosquito population.
“The idea to move from here on out would be to try to spread these guys around the city as much as possible,” Daley said.
Neighborsgo reporter Daniel Houston can be reached at 214-977-8024.