Laboratory Evaluation of Compounds for Repellency Against the Cat Flea, 1994

Thirty compounds were screened for repellency against the adult cat flea and deet (N,N-diethyl-m-toluamide) was used as a standard for comparison. The compounds tested were obtained from the USDA-ARS Medical & Veterinary Entomology Research Laboratory, Gainesville, FL. One pair of knee-high white tube socks (80% cotton, 17% polyester, 3% Lycra, Dupont) was treated with a repellent in acetone solution at an estimated rate of 1 mg/cm2. Each sock was soaked in a solution of 950 mg technical repellent in 100 ml of acetone until the entire amount of solution was absorbed into the sock. The control socks were soaked in 100 ml of acetone. Both pairs of socks were then air-dried for two hours. Each trial was begun by the subject pulling on an under-layer of nylon stockings over his trousers before putting on the treated or control socks. The subject walked for three minutes in a 1 × 1 × 0.5 m square aluminum arena. The arena floor was covered with carpet and was infested before each trial with 200 newly emerged adult cat fleas. After the three minute trial period the subject removed each sock by rolling it off his leg and foot and placing it in a plastic bag which was then frozen to kill the fleas before they were counted. After each trial the carpet was vacuumed to remove fleas that did not attack the subject. To protect the carpet from contamination, the subject wore rubber sandals over the treated socks. Each trial was completed with the same subject used as treatment and control. Compounds which had percent repellency <70% were eliminated. For the remaining effective compounds, tests were replicated four times on different days for each repellent.