Oviposition attractants and stimulants for the sandfly Lutzomyia longipalpis (Diptera: Psychodidae).

Oviposition preferences of Lutzomyia longipalpis Lutz & Neiva for surfaces containing frass (colony remains), larval rearing medium, and rabbit feces were investigated in the laboratory. In oviposition choice chambers, significantly more eggs were laid on sites containing frass, larval rearing medium, or rabbit feces than on untreated control sites. Experiments using unwashed and washed materials indicated, for the first time, the presence of chemical oviposition attractants or stimulants or both in larval medium (consisting of equal weight proportions of rabbit feces, potting compost, sand, and Daphnia). In an olfactometer, aroma from rabbit feces strongly attracted ovipositing females, and significantly higher numbers of eggs were laid in the olfactometer test chamber containing the rabbit feces than in the untreated control chamber. In comparisons of oviposition responses to hexane and distilled water extracts of rabbit feces, only the water extract was attractive. Similarly, the distilled water extract of rabbit feces proved to be an oviposition stimulant. Females kept individually with filter papers impregnated with the extract of feces oviposited earlier and survived longer than females kept with untreated papers.