Optimizing ovitrap use for Aedes aegypti in Cairns, Queensland, Australia: effects of some abiotic factors on field efficacy.

Insecticide-treated lethal ovitraps are used for control of the dengue vector Aedes aegypti in north Queensland, Australia. In an effort to optimize their use, the influence of deployment height, premise shading, and protection from wind on trap efficacy was assessed in field experiments. Sticky ovitraps were used as a proxy for lethal ovitraps because they provide a direct measure of adult visitation rates. Sticky ovitraps deployed at ground level for 1 wk captured significantly more female Ae. aegypti (mean +/- SE, 1.7 +/- 0.4) than those set at 1.75-m elevation (1.0 +/- 0.3). Setting traps on the leeward side of houses significantly improved collections during a dry season experiment but not in the wet season. Traps set at lightly or heavily shaded premises performed equally well. To determine the optimum number of ovitraps to set per premise, five treatments making up different numbers of traps (1, 2, 4, 6, or 8) were trialled in a Latin square experimental design. Female Ae. aegypti collections increased as more traps were deployed, although mean collections by using 4 (2.6 +/- 0.6), 6 (2.4 +/- 0.5), or 8 traps (4.8 +/- 1.3) could not be separated statistically, suggesting that 4 traps was the optimum number for routine deployment.