Tuesday, September 29, 2009

Stop Biting ME!!!

Every summer at sleep away camp, my flesh became a feasting ground for those local country mosquitoes. That famous OFF spray that my mother packed never seemed to help, but it did reduce the number of bites. I should be thankful, more than a mosquito has never bitten me, but just how do bug repellents work?

Mosquito's are attracted three ways to humans. They are attracted to body heat; body temperature may rise during emotional or physical activities. They are also attracted to the carbon dioxide Humans exhale making people more susceptible after exercising or exerting themselves, releasing more carbon dioxide. Last, they are attracted to lactic acid, secretions our skin produces. In some species, female mosquitoes can only hunt for human blood using the scent of lactic acid.

The common active ingredient found in OFF and many other bug repellents is DEET. DEET, or N,N-diethyl-meta-toluamide, is the leading active ingredient world wide against insects. They distort the receptors on the mosquito's antennae, and make the skin unappetizing for future bites. It has also caused health concerns with rare adverse affects including headache, disorientation, nausea, confusion, irritability, difficulty in sleeping, convolutions and death. Products containing a low concentration of DEET are effective and usually safe when used as directed. Adverse effects are incredibly rare in low concentrations, but may occur in prolonged use or if ingestion occurs. Picaridin, the active ingredient found in Cutter Advanced Picaridin Repellent, (chemical name: 2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester), works similarly to DEET but has been used as a safer alternative with a "fresher lighter scent". It inhibits the mosquito's ability to locate the human by interfering with a specific olfactory receptor on the antennae. Other active ingredients are Oil of Lemon Eucalyptus, p-Mentane-3,8-diol, Methyl nonyl ketone, IR3535 (Avon Skin-So-Soft) and Oil of Citronella.
For area or clothing usage, popular ingredients are Permethrin, Allethrin and Metofluthrin.

What I found more interesting was WHY mosquitoes bite in the first place. Once having 37 mosquito bites (and a few choice words) after sitting in the park for about two hours at dusk, I took a trip to my local hospital getting a Benadryl shot for my widespread allergic reaction. My friend, however, had only one or two bites on his arms but rarely ever attracted mosquitoes. Female mosquitoes (males are not capable of biting) bite in order to produce the blood lipids they need to lay eggs. Like many species, these females are also selective about what their optimum blood choices are at a distance of 50 meters away. Scientists have found that some people who may process cholesterol more efficiently than others will have the by-product on their skin, thus attracting mosquitoes. Genetics also accounts for 85% of our susceptibility to the biting. The next time I get an awful mosquito bite ready to swell, I must remember to thank my mother.