Identification of oviposition attractants for Culex quinquefasciatus from fermented Bermuda grass infusions

Compounds which attract and stimulate oviposition by gravid Culex quinquefasciatus were isolated and identified from a fermented Bermuda grass infusion. The neutral portion of the ether extract of the aqueous infusion contained the stimulatory materials. Fractionation by liquid chromatography yielded an active fraction containing phenol, 4-methylphenol, 4-ethylphenol, indole and 3-methylindole. A blend of the 5 compounds strongly stimulated oviposition, as did blends of any 4 of them. Bioassays with individual compounds showed that only 3-methylindole consistently induced oviposition, in concentrations spanning 5 orders of magnitude.