LABORATORY AND FIELD-EVALUATION OF DEET, CIC-4, AND AI3-37220 AGAINSTANOPHELES DIRUS (DIPTERA, CULICIDAE) IN THAILAND

Laboratory and field tests of the repellents diethyl methylbenzamide ( deet), 1-(3-Cyclohexen-1-yl-carbonyl)-2-methylpiperidine (AI3-37220), and (2-hydroxymethylcyclohexyl) acetic acid lactone (CIC-4) were condu cted against Anopheles dirus Peyton & Harrison, the principal malaria vector in Thailand. In the laboratory, An. dirus was more sensitive to CIC-4 than either AI3-37220 or deet. The duration of protection provi ded by each repellent in laboratory tests increased with higher concen trations of repellents and when exposed in cages containing fewer mosq uitoes. A field study in Chanthaburi Province, southeastern Thailand, during November 1993 tested 25% (wt:wt) ethanol solutions of each repe llent against An. dirus. In contrast to the laboratory experiments, pr otection provided by AI3-37220 was significantly better than either de et or CIC-4 and there was no significant difference between deer and C IC-4. Protection provided by deer and CIC-4 fell to below 95% 2 h afte r repellent application, whereas AI3-37220 provided >95% protection fo r 4 h. The protection provided by all repellents fell to less than or equal to 65% 7 h after repellent application.