| Anopheles gambiae is arguably one of the most dangerous insects today due to its effectiveness as a vector of human malaria. In Western Kenya, larvae of this mosquito are commonly found in puddles associated with freshly disturbed soils. Laboratory choice tests were performed with different soil types and synthetic chemicals to determine which stimulated or inhibited oviposition. Some soil samples were found to stimulate oviposition 2 fold over a pure water control while others reduced oviposition significantly. Effects of particular soils varied over time. Geosmin, 2-methylisoborneol, phenol, p-ethylphenol, and o-phenylphenol stimulated greater than 60% ovipositional events compared to distilled water control, while indole and skatole inhibited greater than 60% oviposition. Further testing needs to be done to determine if they are biologically active in the field. Visual observations of An. gambiae females were performed within a 21 x 2.5 x 12 cm Plexiglas arena to identify and quantify behavior details of oviposition. Many hypergravid An. gambiae laid eggs readily on moist substrates while others took longer to initiate oviposition, but most accomplished egg deposition the night tested. Once begun, most females deposited all their eggs in one sitting with eggs dropping every 5 +/- 1 sec. The overall impression was that ovipositional sequence is quite simple and reproducible. |
