Immo A. Hansen
Dept of Biology
New Mexico State University
Las Cruces,
NM 88003-8001
(575) 646-7719
immoh@nmsu.edu

NMSU Department of Biology


About NMSU


About Las Cruces, New Mexico



Bioassays

Our lab offers collaborations on a variety of mosquito assays. We test mosquito repellents, attractants, larvicides, and insecticides.
Y-Tube
Wind Tunnel
Feeding Assay
Larvicides
CDC Bottle Test
Arm in Cage
Field Testing

Y-Tube

This is a powerful assay to test the efficacy of mosquito repellents and attractants. We used this assay in our 2015 paper, The Efficacy of Some Commercially Available Insect Repellents for Aedes aegypti (Diptera: Culicidae) and Aedes albopictus (Diptera: Culicidae), where we discovered that Victoria Secret Bombshell perfume is a strong mosquito repellent.

In this assay, mosquitos are released into the mosquito holding chamber of the plexiglas Y-tube and have the choice of flying towards one of two chambers. The treatment chamber usually contains a human hand that can be treated with different repellants or another form of attractant. The control chamber is empty.

The data produced with these experiments enable us to calculate repellency or attractant indexes for specific treatments or products.

Check out these news articles about our research!
Huffington Post
USA Today
Daily Mail
USA Today

Wind Tunnel

The wind tunnel assay, similar to the Y-tube, can be used to test mosquito repellants and attractants in a more natural setting. In this setup, a human bait sits upwind from a three chambered mosquito taxis cage. Mosquitoes are loaded into the middle chamber and are given the choice to either fly towards the bait or away or stay where they are.

We used this assay in our 2017 paper to show the efficacy of a variety of wearable mosquito repellent devices. The data produced with wind tunnel experiments can be used to calculate repellency or attractant indexes for specific treatments or products.

Check out our video on El Paso Proud to see how we test mosquito repellants in the wind tunnel.

Check out our recently published paper, Efficacy of Some Wearable Devices Compared with Spray-On Insect Repellents for the Yellow Fever Mosquito, Aedes aegypti (L.) (Diptera: Culicidae), testing mosquito repellants as well as these recent news articles!
Science Magazine
EurekAlert
iNVISIVERSE

Feeding Assay

Mosquito feeding assays can be used to test the efficacy of repellent or insecticide-treated clothing or screen mesh in repelling or killing mosquitoes.

We use artificial glass feeders to blood-feed mosquitoes that are located within a cage. The mosquitoes have to land on and feed through the fabric to get to the blood and are so exposed to it.

We measure engorgement rates to determine repellency effects of the fabric treatments. If mosquitoes take blood the fabric treatment was not effective. We can also measure survival rates over time in case the fabric is treated with pyrethroids or other insecticides.

The results of feeding assay experiments can be used the efficacy of specific treatments for clothing, bed nets, etc.

Larvicides

Larvicides are an important component for integrated mosquito control efforts. They are an effective tool to reduce larval habitat which is critical for mosquito reproduction.

For testing of larvicide we follow the WHO guidelines for Laboratory and Field testing of mosquito larvicides. Mosquito larvae are exposed to different concentrations of the larvicide and mortality is recorded over time.

The data produced in these experiments are used to calculate the LC50 (lethal concentration that kills 50% of all mosquito larvae in 24 hrs) and the LC90. This information can be used to determine how much larvicide should be used for treating mosquito larval habitat as well as for determining levels of larvicide resistance in specific populations of mosquitoes.

CDC Bottle Test

This test is used to determine the efficacy of specific insecticides in killing adult mosquitoes. It can also be used to determine the levels of insecticide resistance in specific mosquito populations.

We follow the CDC guidelines when performing this test. Mosquitoes are transferred into bottles that have been treated with various insecticides and their mortality is monitored over time.

This test can be used to compare the efficacy of novel and old adulticides as well as to determine resistance to specific adulticides.

Arm in Cage

...

Field Testing

The most time-consuming and expensive assay for repellents or repellent devices is the field test. For this test an experimenter is set up in the field within mosquito habitat at times when mosquitoes are most active. The experimenter wears a protective suit that only exposes the arms. A second experimenter catches all mosquitoes that land on the test person using an aspirator.

This assay can be used to test the efficacy of spray-on repellents, lotions, repellent devices, or repellent-treated clothing.

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