EVALUATION OF THE FLUSHING OUT ACTIVITY OF PYRETHROIDS ON TRIATOMA-INFESTANS

Tetramethrin, deltamethrin and cypermethrin formulated as fumigant tab lets or spray(ing) solutions showed flushing out activity on Triatoma infestans. Fumes arising from the tablets were analysed by gas chromat ography. The proportion of pyrethroid liberated was between 10 and 20% of the original amount formulated. The flushing out activity shown wa s dependent on the pyrethroid compound, insect stage and sex. In gener al deltamethrin proved the most active flushing out agent and cypermet hrin the least active. Maximal activity was shown in the combination o f nymphs and tetramethrin. Nymphs of Rhodnius prolixus were only flush ed out by deltamethrin. In all cases, deltamethrin and cypermethrin yi elded 100% mortality 7 days after exposure to the pyrethroid fumes, wh ile tetramethrin was not a killing agent.