Sub-additive effect of conspecific eggs and frass on oviposition rate of Lutzomyia longipalpis and Phlebotomus papatasi.

Oviposition behavior is a fairly neglected aspect in our understanding of the biology of sand flies. In this study, we used a comparative approach using both new- and old-world species (Lutzomyia longipalpis and Phlebotomus papatasi) in choice and no-choice oviposition chambers to evaluate the effect of old sand fly colony remains (frass), conspecific eggs, and their combination on oviposition rates of these sand flies. We also tested the effect of egg washing with de-ionized water on oviposition rates. In both choice and no-choice experiments, sand fly species laid more eggs on a substrate containing frass. The effect of eggs alone was not significant but showed a positive trend. Furthermore, for both sand fly species, the effect of the combined treatment was sub-additive suggesting a potential inhibitory effect of one factor on the other. Egg washing did not have a significant effect. The choice and no-choice experimental designs did not differ in their outcomes suggesting the choice-design could serve as an effective high throughput method for screening oviposition attractants/stimulants.