Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2005
Publication Date: 1/1/2006
Citation: Klun, J.A., Khrimian, A., Debboun, M. 2006. The repellent and deterrent effects of ss220, bayrepel and deet against aedes aegypti, anopheles stephensi and phlebotomus papatasi. Journal of Medical Entomology. 43: 34-39.
Interpretive Summary: Three chemicals named SS220, Deet, and Bayrepel are known to protect humans against the bites of blood-feeding insects carrying disease by applying them topically to skin. Despite the widespread knowledge of the protective qualities of these compounds, there was little information available on exactly how they influence insect behavior and thereby suppress insect biting. The behavioral responses of mosquitoes and sandflies were studied, and it was discovered that each of the three chemicals caused the insects to make oriented avoidance movements away from a source of the chemical. This is known as a repellent effect. In addition, it was observed that when the insects were simultaneously exposed to skin treated with chemical and untreated skin, they bit only on skin without the chemical. When treated and untreated skin surfaces were covered with cloth, the insects bit only through cloth covering untreated skin. This observation proved that the insects used their sense of smell to detect the chemicals and avoided biting where the chemical odorant was present. The biting deterrent and repellent effects explain how the chemicals affect insect behavior and thereby manifest their personal-protection properties for humans.
Technical Abstract: Observations on the behavior of Aedes aegypti, Anopheles stephensi mosquitoes and the sand fly Phlebotomus papatasi in the presence of Deet, SS220, and Picaridin® topically applied to the skin of human volunteers showed that the insects were deterred from feeding on and repelled from surfaces emanating these compounds. When offered a 12 cm2 area of skin, one half treated with compound and one half untreated, the female insects fed almost exclusively on untreated skin. The sand fly and the mosquitoes detected treated surfaces without flight searching or by touching the skin surfaces. When the respective skin areas were covered with cloth, to prevent insect contact with skin surfaces, insects landed on and intensively bit through cloth covering untreated skin. This proved that the chemicals deterred insect feeding as a result of compound perceived in the vapor phase rather than by a tactile interaction with chemical. When cloth, one half untreated and the other half treated with chemical, was placed over untreated skin, the insects bit through the untreated cloth and avoided the treated cloth. In the presence of any of the three chemicals, no matter how presented to the insects, overall biting activity was reduced by about 50% relative to controls. This reduction evidenced a repellent effect for the compounds. Despite the fact that Deet, SS220 and Picaridin are often called insect repellents, they should also be classified as feeding deterrents because data show that they exert both effects upon the behavior of mosquitoes and sand flies. Heretofore, the combined effects of these compounds was not known.