Evaluation of the Flushing out Activity of Pyrethroids on Triatoma Infestans

Tetramethrin, deltamethrin and Cypermethrin formulated as fumigant tablets or spray(ing) solutions showed flushing out activity on Triatoma infestans. Fumes arising from the tablets were analysed by gas chromatography. The proportion of pyrethroid liberated was between 10 and 20% of the original amount formulated. The flushing out activity shown was dependent on the pyrethroid compound, insect stage and sex. In general deltamethrin proved the most active flushing out agent and Cypermethrin the least active. Maximal activity was shown in the combination of nymphs and tetramethrin. Nymphs of Rhodnius prolixus were only flushed out by deltamethrin. In all cases, deltamethrin and Cypermethrin yielded 100% mortality 7 days after exposure to the pyrethroid fumes, while tetramethrin was not a killing agent.