Tests of pyrethroid vaporising mats against Aedes aegypti (L.) (Diptera: Culicidae)

Abstract

Vaporising mats are used to volatilise small amounts of pyrethroid to prevent mosquito nuisance within houses. A small absorbent mat containing pyrethroid is placed on a 5- to 6-W electric heater. The mat surface temperature is about 125°C. Pyrethroid is released for several hours at a slowly diminishing rate. In tests, no evidence of degradation of bioallethrin was obtained. Vapour from mats inhibited biting by female Aedes aegypti (L.) and caused knockdown and kill. A commercial mat containing 88 mg allethrin was as effective as a mosquito coil containing 0·25% allethrin. In laboratory-made mats, 40 mg bioallethrin or 19 mg S-bioallethrin gave equal or better action than allethrin. Additives, such as piperonyl butoxide, mineral oil or antioxidant slightly reduced the rate of emission of pyrethroid and diminished the bite inhibitory and knockdown effects.