Durability of Permethrin as a Potential Clothing Treatment to Protect Against Blood-feeding Arthropods1

The durability of permethrin (3-phenoxyphenyl) methyl cis, trans (±)-3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropanecarboxylate) was studied to determine its potential as a clothing treatment for protection against bloodsucking arthropods. Minimum effective dosages in cloth that caused 100% mortality in 15 min ranged from 0.008–0.125 mg/cm2 with 4 species of mosquitoes and 2 species of flies when the insects were exposed to the treatment for only 10 sec. Minimum effective dosages that caused 100% mortality in 15 min for a 5th species of mosquito resistant to DDT and a flea ranged from 0.032–0.25 mg/cm2 with an exposure of 30 sec. The lone star tick, Amblyomma americanum (L.), required a 2-min exposure to obtain similar mortality with a dosage of 0.016 mg/cm2. Even after 33–50 cold water rinses of treated cloth, dosages of 0.125–0.25 mg/cm2 still killed 100% of the yellow fever mosquito, Aedes aegypti (L.) (30-sec exposure) and A. americanum (2-min exposure). All A. aegypti were killed despite 2 soapy washes of the cloth. Cloth treated with similar dosages was effective after a 1-month exposure to outdoor weathering. Such treatments of clothing could be used for personal protection from blood-feeding arthropods and would also kill a wide variety of these pests.