Abstract:
Phlebotomine sand flies transmit many viral protozoan and bacterial pathogens of public
health importance. Knowledge of the ecologic factors influencing their distribution at local
scale can provide insights into disease epidemiology and avenues for targeted control. Animal sheds, termite mounds and houses are important peri-domestic and domestic habitats
utilized by different sand flies as resting or breeding habitats. However, our knowledge for
selection of these habitats by sand flies remains poor. Here, we tested the hypothesis that
these habitat types harbor different composition of sand fly species and differ in their volatile
chemistry that could influence sand fly selection. To achieve this, we employed CDC light
traps following a cross-sectional survey to investigate the distribution of sand flies in the
three habitats in an endemic site for leishmaniasis in Kenya. The study was carried out during the dry season, when sand flies are optimally abundant in 2018 and 2020. Sand fly abundance did not vary between the habitats, but species-specific differences in abundance was
evident. Measures of sand fly community structure (Shannon diversity and richness) were
highest in animal shed, followed by termite mound and lowest inside human dwelling
(house). This finding indicates broader attraction of both sexes of sand flies and females of
varying physiological states to animal sheds potentially used as breeding or resting sites,
but also as a signal for host presence for a blood meal. Furthermore, gas chromatographymass spectrometric analysis of volatiles collected from represented substrates associated
with these habitats viz: human foot odor on worn socks (houses indoors), cow dung (animal
sheds) and termite mounds (enclosed vent), revealed a total of 47 volatile organic compounds. Of these, 26, 35 and 16 were detected in human socks, cow dung and enclosed termite vent, respectively. Of these volatiles, 1-octen-3-ol, 6-methyl-5-hepten-2-one, α-pinene,
benzyl alcohol, m-cresol, p-cresol and decanal, previously known as attractants for sandflies
and other blood-feeding insects, were common to the habitats. Our results suggest that habitat volatiles may contribute to the composition of sand flies and highlight their potential for
use in monitoring sand fly populations.
