Abstract
BackgroundPhlebotomine sand flies are vectors of human leishmaniases, important neglected tropical diseases. In this study, we investigated diel patterns of oviposition behavior, effects of visual cues on oviposition-site selection, and whether these affect the attraction of gravid Phlebotomus papatasi (Scopoli), the vector of old-world cutaneous leishmaniasis, to olfactory cues from oviposition sites.Methodology/principal findingsTo evaluate these questions, we conducted a series of experiments using attraction and oviposition assays within free-flight test chambers containing gravid females entrained under a 14:10 hrs light:dark photoperiod. By replacing sticky-screens or moist filter papers every three hours, we showed that oviposition site search occurs mainly in the latest part of the night whereas peak oviposition occurs during the early part of the night. Behavioral responses to olfactory oviposition cues are regulated by time-of-day and can be disrupted by transient exposure to a constant darkness photoperiod. Gravid females, but not any other stage, age, or sex, were attracted to dark, round oviposition jars, possibly resembling rodent burrow openings. This visual attraction disappeared in the absence of an illumination source. Egg deposition rate was not affected by jar color. Olfactory cues had the strongest effect when the visual cues were minimal.Conclusion and significanceOur study showed, for the first time, that visual cues in the form of oviposition-site color, lighting level, and photoperiod are important in guiding the oviposition behavior of phlebotomine sand flies. Furthermore, such visual cues could modify the flies’ sensitivity to olfactory oviposition cues. Our results suggest that chemosensory and visual cues are complementary, with visual cues used to orient gravid females towards oviposition sites, possibly at long- to medium-ranges during crepuscular periods, while olfactory cues are used to approach the burrow in darkness and assess its suitability at close-range. Implications to sand fly control are discussed.
Highlights
Phlebotomine sand flies (Diptera: Psychodidae) transmit protozoan parasites (Leishmania spp.), as well as pathogenic bacteria (Bartonella bacilliformis) and viruses [1,2,3]
We investigated diel patterns of oviposition behavior, effects of visual cues on oviposition-site selection, and whether these affect the attraction of gravid Phlebotomus papatasi (Scopoli), the vector of old-world cutaneous leishmaniasis, to olfactory cues from oviposition sites
For the first time, that visual cues in the form of oviposition-site color, lighting level, and photoperiod are important in guiding the oviposition behavior of phlebotomine sand flies
Summary
Phlebotomine sand flies (Diptera: Psychodidae) transmit protozoan parasites (Leishmania spp.), as well as pathogenic bacteria (Bartonella bacilliformis) and viruses [1,2,3]. Leishmaniasis is distributed in the poorest regions of the world, and considered a neglected disease in terms of under-reporting, under-funding of research, and inadequate health care [6,7,8]. With no vaccine to protect against the etiologic agent, reduction of exposure to sand fly bites using insecticides is the most effective prevention measure [6, 9, 10]. This strategy is seriously constrained, by the evolution of insecticide resistance, which renders residual sprays less effective [10, 11]. A more focused, targeted, and efficient control method is urgently needed [15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
