Summary

The insecticide OMS-33 was evaluated as a candidate for future use in the problem areas of Central America where the vector, A. albimanus, had become resistant to DDT. Field trials of partial spraying of the interior surface, with 60 grams/35 days/house showed the efficiency of this method. The extremely rapid turnover of the sprayable surfaces, occurring especially just before and in the beginning of the season of highest transmission, makes the use of short intervals between the spraying cycles desirable. The volatility and the high price of the insecticide also makes frequent application of small quantities preferable. The A. albimanus that enter the houses for biting stay for a considerable time in the houses resulting in a very high kill by the vapor of the insecticide.

The evaluation of the insecticide entailed the investigation of several epidemiological factors for which some new techniques were established, for instance, methods of differential studies on the duration of presence of A. albimanus inside the houses before and after biting; studies of A. albimanus by coloration with fluorescent dye and direct observation of their behavior in ultraviolet light, and studies on the techniques of measuring the fumigant effect of the insecticide.