Evaluation of chlorphoxim used against Anopheles albimanus on the south coast of Mexico: 1. Results of indoor chlorphoxim applications and assessment of the methodology employed.

While the malaria outlook in recent years has either remained the same or shown improvement in some parts of South America, the number of reported malaria cases in certain parts of Middle America has continued to increase (I). The eighteenth report of the WHO Expert Committee on Malaria, published in 1980 (2), lists twelve constraints impeding the progress of antimalaria activities. These include administrative and operational problems, difficulties posed by prevailing social patterns of behavior, parasite resistance, vector resistance, the degree of vectorhuman contact, changes in vector behavior leading to avoidance of treated surfaces, and a poor understanding of vector behavior. In the past, the strategy of indoor malaria spray programs has depended upon the efficiency of the insecticides used to control vector populations with divergent behaviors and resistance patterns. The behaviors involved have usually included a wide range of biting and resting habits that influence the insecticide contact time needed to effectively control those members of the vector population involved in the transmission cycle. However, with the mounting resistance of malaria vectors to insecticides and the continuing alteration of environmental and ecological behavior patterns, it is becoming increasingly evident that there is a need to modify this vector control strategy. Specifically, it is necessary to develop a strategy that includes thorough study of the target vector’s bahavior, especially as it relates to transmission of the parasite. In this vein, a primary aim of the Malaria Research Center in Tapachula, Mexico, has been to develop an entomologic and epidemiologic strategy appropriate for Mexico’s malaria problems, one that may also prove relevant for dealing with malaria problems in other portions of the hemisphere. The specific work reported here, involving trial applications of chlorphoxim, was directed at determining that insecticide’s efficacy in controlling Anopheles albimanus and at further investigating this susceptible vector’s indoor behavior.