Mosquito trapping program ramps up
County turns to tech to help cut down populations
When bitten by a mosquito, you swat the pest away and cope with an annoying but temporary itchy spot for a few hours or days. But some mosquito bites can spread viruses and even cause serious diseases.
In this area, the main concern is West Nile virus, which in a small number of cases can lead to serious side effects. However, mosquitoes may also carry such problematic diseases as Zika virus, yellow fever, Chikungunya virus, dengue fever and malaria.
Thus as temperatures heat up and mosquito activity increases, so, too, do efforts to keep the pest under control.
Mosquitoes infected with West Nile virus have been found in samples near the East Wetlands, officials reported in early June. It’s become an annual occurrence during Yuma’s hot weather, and it’s why Yuma County conducts an aggressive mosquito trapping program throughout the summer.
Fortunately, for the second year there’s a new technology to aid in that intensive chore covering the county’s 5,519 square miles. The BG-Counter automatically differentiates mosquitoes from other insects entering the trap, counts them and wirelessly transmits the results to a cloud server.
It saves a lot of driving, especially when considering the area to be sampled extends from the international border to Aqua Caliente in far eastern Yuma County, said Richard Cuming, environmental vector control specialist II with the Yuma County Public Health Services District.
The BG-Counter “is very helpful,” he said. “We can use it for remote monitoring. We can put traps at Fisher’s Landing and get the results every morning without having to drive all the way out there. We know how many mosquitoes we’ve captured and when they’re active. That helps us schedule treatment to get best results. We want them when they’re resting and not flying around.”
The technology also helps determine the effectiveness of treatment, he said. “If we fog and the numbers don’t go down, we need to figure out why. Maybe they’ve become resistant, and we need to change chemicals.”
The mosquito season can start as early as late February and run through October. During those months, 15 to 40 traps are set out every two weeks along the river and in town, whereever Cuming gets complaints. The traps are set out in the afternoons with dry ice, which gives off carbon dioxide that attracts mosquitoes (the same thing that attracts them to humans). The mosquitoes typically feed from evening to morning. In the early mornings, Cuming checks the traps for the number and species of mosquitoes. Any Culex species mosquitoes, the main vector for West Nile virus, are then tested for the disease.
Mosquito control is a team effort. Working alongside Cuming for the past 24 years is Joey Martinez, another environmental vector control specialist II. They also work with the Yuma County Pest Abatement District, and the Quechan Indian Nation has vector control on its side of the Colorado River. “The three agencies work together on the problem,” Cuming said.
Fogging is the treatment of last resort, and is primarily used along the river. In more developed areas, Cuming and his team work with homeowners to identify and eliminate breeding sources. These can be anything with even a very small amount of standing water, such as old tires, pet dishes, planters and toys. For water sources that can’t be emptied, larvicides may be applied to keep larvae from maturing into adult mosquitoes, but they need to be applied carefully.
“Hundreds if not thousands of mosquitoes can be born in a very small amount of water, even in a bottle cap,” said Yuma County Communications Director Kevin Tunell. “That’s why we urge people to police their yards. Anywhere water can puddle, mosquitoes can breed.”
Other recommendations to reduce the risk of mosquito bites include having good screens on windows and doors; wearing protective clothing such as long sleeves and long pants when outside from dusk to dawn, when mosquitoes are most activel and using a mosquito repellent containing DEET, picaridan or oil of lemon eucalyptus.
Mosquitoes become infected with West Nile virus when they feed on infected
birds. The infected mosquitoes then transmit the disease to humans by biting them.
Approximately 80 percent of people are who infected with West Nile virus will show no symptoms, but up to 20% may have mild symptoms such as fever, headache and body aches, according to the Centers for Disease Control and Prevention website at www.cdc.gov/westnile. About 1 in 150 people infected with the disease will develop severe illness and may require hospitalization. It can also lead to more serious conditions, such as meningitis or encephalitis.
“One of the beauties of letting everybody know (about these findings) goes with the detection that goes on,” Tunell said in an earlier interview with the Yuma Sun. “We have the Yuma County Public Health District, we have vector specialists that go out hunting West Nile so when they do find (it), they typically go into a pattern where they treat that area and they test and retest.”
He concluded: “Mosquitoes haven’t changed, and the disease they carry hasn’t changed, but the way we respond to breakouts is getting better.”