Repellency of deet to nymphs of Triatoma infestans

The repellency of N,N-diethyl-3-methylbenzamide (deet) to Triatoma infestan s (Klug) (Hemiptera: Reduviidae) was evaluated using third-instar nymphs an d a video tracking technique. Three experimental designs were used: (a) the test arena floor was divided into two halves, only one of which was treate d with deet; (b) the arena floor was divided into an inner circle and an ou ter ring, only the latter treated with deet; (c) half of the test arena was covered by a filter paper roof treated with deet (out of reach of the nymp hs). In all three types of experiment, a repellent effect was demonstrated proportional to the dose of deet. When a host (pigeon) was shielded by deet -treated gauze, the rate of blood-feeding by the nymphs was inhibited. Topi cal pre-treatment of the nymphs with N-ethylmaleimide, to block chemorecept ion, inhibited the repellency.