The thigmotropic oviposition response of the sandfly Lutzomyia longipalpis (Diptera: Psychodidae) to crevices

Two experiments were carried out to investigate if Lutzomyia longipalpis would be attracted and stimulated to lay eggs in crevices. In the first experiment, females were introduced into a chamber and offered the choice of oviposition in a test site consisting of artificial crevices, and an open control site. Significantly more eggs were laid in the crevices of the test site than in the control site. In the second experiment, females were individually isolated in vials containing vertically placed filter papers, either folded to provide artificial crevices or arranged to offer two flat surfaces. The females isolated with the folded papers laid significantly more eggs than those isolated with the flat papers. The post-oviposition survival rates of both groups of females were, however, similar. It is suggested that the oviposition preference of the fly for the surface crevices was due to thigmotropic behaviour.