Laboratory and field trials of four repellents with Culex pipiens (Diptera: Culicidae)

During Operation "Desert Shield," 16 volunteers field-tested four insect repellents (deet, the lactone CIC-4, and the piperidine compounds AI3-37220 and AI3-35765) against biting mosquitoes at King Fahd Airport, Eastern Province, Saudi Arabia. CIC-4 and AI3-37220 (25% wt/vol) provided effective (> 90%) protection against bites for 4 h. Deet and AI3-35765 protected for only 2 h. The compounds subsequently were evaluated for repellency against laboratory-reared Culex pipiens L. CIC-4 was more effective than deet, AI3-37220, or AI3-35765 at the ED50 but not at the ED95 level in initial sensitivity tests using human volunteers. At the ED95 level, deet provided significantly better protection than either piperidine compound. In laboratory duration tests, AI3-37220 provided 8 h of effective (> 90%) protection against Cx. pipiens bites, deet and AI3-35765 7 h of protection, and CIC-4 2 h of protection.