Research at NMSU looks at the effectiveness of mosquito repellents
Mosquitoes can carry many deadly diseases, including Zika, West Nile Virus, and dengue fever. Last year, there were 33 cases of West Nile Virus in New Mexico. At New Mexico State University research is being done to gain more understanding of the insect’s life cycle in order to disrupt the process of disease transmission.
Dr. Immo Hansen works at the Hansen laboratory on campus as the principal investigator, studying disease-transmitting arthropods, which includes mosquitos.
Recently, the lab has been testing insecticide resistance in mosquitoes and the effectiveness of various repellents. What they’ve found is that chemical repellents are the most effective for repelling mosquitoes for hours at a time.
Dr. Hansen says that compared to a control, Deet cut mosquito attraction by roughly 40%. According to Hansen, some essential oil repels mosquitoes at a similar rate, but effectiveness is short-lived. Unlike insecticide, chemical repellents offer the user long-lasting protection without harming the ecosystem.
“Especially now that mosquito season is peaking, these repellents are flying off the shelves, and some work better than others, so it’s really important to know which ones are the good ones and which ones are the not so good ones,” Hansen said.
Dr. Hansen and his team use a wind tunnel to conduct research that helps determine how effective the repellents are.
“When you test mosquito repellent in the field, you have the problem that the wind is unpredictable, it can change directions and blow away your repellents. In order to address this problem, we are using the small wind tunnel facility here in order to get a constant airflow,” Hansen said.
The wind tunnel provides a stable environment to test repellents. By using a cage filled with a predetermined number of mosquitoes and a bait volunteer upwind, the team is able to calculate the effectiveness of any given repellent.
Dr. Hansen says that when looking for an effective repellent, you should look for one of the following active ingredients: deet, picaridin, ir3535, and lemon eucalyptus oil. These repellents are all proven to be protective for hours on end. But to Dr. Hansen, the best solution to keeping mosquitos at bay is keeping them out of your living space.
“Check the screens on your windows, make sure there are screens, and make sure they don’t have holes, keep them outside of your house,” Hansen said.
The second thing is to get rid of standing water in your backyard. This is breeding habitat for mosquitoes, and just getting rid of this habitat is going to reduce the number of mosquitos in your local area. Dr. Hansen says homes that have standing water areas, such as a pond, mosquito fish are highly efficient at controlling mosquito populations, and one of his favorite methods of mosquito control.
“I have a pool in my backyard and I have a whole swarm of mosquito fish in there … You don’t even have to feed them, they live on insects that fall into the water, and they will take care of mosquitos, they will just eat all the larvae,” Hansen said.
As for insecticides, Dr. Hansen sees them as a temporary solution. Insecticides are effective at killing mosquitos, but they disrupt the surrounding ecosystem and can be harmful to pollinators. On top of this, mosquitos actually gain resistance to insecticides over time if used too frequently:
“It is an effective method, but doing all of these other things – reducing breeding habitats, using fish and screening your house is probably the more effective long-term solution,” Hansen said.
According to Hansen, being prepared and protected is your best chance in preventing vector-transmitted illnesses.