Sunday, June 26, 2011

Possible Perfume to Deter Mosquito Bites

Every time we exhale carbon dioxide, we are attracting female mosquitoes. However, there might be a new way to prevent mosquitoes from biting by overloading the nerve cell that detects carbon dioxide. According to Nature (, Stephanie Lynn and Nan Li from the University of California-Riverside, have found a combination of chemicals (2,3-butanedione or diacetyl) that prevent the female mosquito from finding hosts. Diacetyl smells like butter or cheese and it causes the mosquitoes’ nerve cell to continue to fire so it can not find the source of carbon dioxide. Instead, the female flies in a random pattern.

There are several advantages of using these chemicals, such as they do not have to be applied directly to skin and the chemcials can be blown over a large area to protect many people. In addition, these chemicals do not interfere with DEET, so the two chemicals can be used at the same time. Currently, diacetyl is found in some alcoholic drinks and it is used to give margarine and popcorn a buttery flavor. However, when it is used at high levels, it can be an irritant and has been linked to a lung disease called bronchiolitis obliterans also known as “Popcorn Worker’s Lung.”

Female mosquito feeding. Photo by Texas A&M University.

Wednesday, June 1, 2011

What Is Making You Itch This Summer?

As we begin to be more active outdoors, we need to remember to protect ourselves from chiggers, which are small red mites. Chiggers develop through four lifestages: egg, larva, nymph and adult. Six-legged larvae hatch from eggs and climb up onto vegetation, so they can crawl onto a passing host. This is the only stage that feeds on humans and animals. Chigger larvae prefer to bite people in places where clothing fits tightly over the skin such as around the waistline, under socks, or where the skin is thin or creased such as around the ankles or the back of knees. Chigger larvae insert their mouthparts into a skin pore or hair follicle, and then inject a digestive fluid to dissolve skin cells. This results in itchy, reddish welts on the skin. After feeding, the larvae drop off of the host to molt into eight-legged nymphs which then molt into adults. Chigger nymphs and adults feed on eggs of springtails, isopods, and mosquitoes. Under favorable conditions, most chiggers complete their development from egg to adult in 40 to 70 days.

Suggestions for Prevention of Chigger Bites:

Avoid sitting on the ground when camping, picnicking, or working outdoors. Wear tightly woven socks, long pants, long sleeved shirts, and high shoes. Also tuck pant legs inside boots and button cuffs and collars as tightly as possible to prevent chiggers from climbing inside your clothes. Apply repellents such as DEET or permethrin to both the skin and clothing. Powdered sulfur is another repellent that can be dusted around the opening of your pants, socks, and boots or rubbed on skin such as over legs, arms and waist.

Suggestions for Relief After Exposure to Chiggers:

Wash clothes in hot, soapy water to kill chigger larvae. Take a hot bath or shower and soap repeatedly; creams or ointments such as hydrocortisone or calamine lotion can be applied to relieve itching temporarily.

Suggestions for Use of Insecticides:

Chiggers sometimes become a problem in home lawns, so chemical control may be needed. Insecticide sprays may provide some temporary reduction of chiggers and they are effective when applied in areas where chiggers and their animal hosts are living and/or traveling. Insecticides containing carbaryl, permethrin, cyfluthrin are some suggestions for control.

Photo of chigger bites. Photo by Michael Merchant, Professor and Extension Entomologist, Texas A&M University.