# Behavioral responses of Phlebotomus papatasi (Diptera: Psychodidae) to host-derived semiochemicals

## TL;DR

This study explores how Phlebotomus papatasi sand flies respond to various host-derived odors, identifying specific chemicals that attract them and how these responses vary by sex and concentration.

## Contribution

The study is the first to investigate the attractant effects of plant- and animal-derived semiochemicals on Phlebotomus papatasi using an olfactometer.

## Key findings

- Octanal, decanal, and 1-octen-3-ol showed significant attractiveness to Phlebotomus papatasi.
- Sex-specific and concentration-based differences were observed in the sand flies' responses to semiochemicals.
- Mixtures of semiochemicals revealed both synergistic and antagonistic interactions in attracting sand flies.

## Abstract

Vertebrate and plant hosts provide arthropods with a range of stimuli to aid in their localization, among which semiochemicals, volatile cues enabling hosts to be located through their odours, stand out as particularly important. Recognizing their potential in vector control, this study investigates semiochemicals as viable alternatives for effective vector management strategies. In this study, behavioral responses of Phlebotomus papatasi (Scopoli, 1786) adults to 11 semiochemicals, derived from plant and vertebrate hosts and previously tested on various vector species, across 3 concentrations (10−2%, 10−3%, and 10−4%) were evaluated using a dual-choice olfactometer. A total of 1,110 females and 1,110 males were individually assayed, with behavioral responses quantified through trap selection and response times. Notably, 1-octanol (10−2%) consistently exhibited the lowest attractiveness, whereas octanal, decanal, 1-hexanol, 1-octen-3-ol, ocimene, linalool oxide, and sulcatone elicited significant attractive effects, with pronounced sex-specific and concentration-based differences. Mixtures, formulated from the most attractive individual concentrations, revealed both synergistic and antagonistic interactions, underscoring the complexity of chemical interplay in mediating host-seeking behavior. Statistical models demonstrated significant interactions among semiochemical type, concentration, and sex, influencing both behavior and decision latency. This study marks the first investigation into the attractant effects of plant- and animal-derived semiochemicals on Ph. papatasi adults within an olfactometer system. The results are expected to provide critical insights into sand fly ecology and the epidemiology of sand fly-borne diseases while contributing to the development of integrated vector management strategies.