Exploring the influence of different habitats and their volatile chemistry in modulating sand fly population structure in a leishmaniasis endemic foci, Kenya

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 chromatography-mass 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.

Community Conversations: A Tool in Improving Health Outcomes and Reducing the Burden of Visceral Leishmaniasis (Kala-azar) in Isiolo County, Kenya

“…This finding has important implications for developing local solutions involving the community for the management and control of invasive Prosopis juliflora in the region as one of the major vector control strategies. This understanding of habitat selection may be useful in managing or controlling sand flies to stop the spread of disease, particularly in emergency epidemic scenarios [11].…”

Behavioural responses of Phlebotomus duboscqi to plant‐derived volatile organic compounds

“…The results also emphasize that differences in odour quality and quantity may determine sand fly responses to plant volatiles (Nyasembe et al ., 2012). Interestingly, p ‐cymene, p ‐cresol and m ‐cresol have been reported as components of the volatiles emitted by fresh livestock dung and termites mounds (Hassaballa et al ., 2021b). They have also been reported to attract gravid S. calcitrans L. in the field (Tangtrakulwanich et al ., 2015; Baleba et al ., 2019).…”

Non-host plant odors influence the tritrophic interaction between tomato, its foliar herbivore Tuta absoluta and mirid predator Nesidiocoris tenuis

“…Retention time in minutes, R.I (Calc) = Retention index calculated based on the C 8 -C 31 n-alkanes of HP-5 MS column, R.I (Lit) = Retention index obtained from literature: A(Hassaballa et al, 2021), B (Antwi-Agyakwa et al, 2021, C(Ayelo et al, 2021), D(Matu et al, 2021), E(Njuguna et al, 2018), F (Adams2, 1995, G(Kihika et al, 2020), H(Diabate et al, 2019), I(Silva et al, 2017), J (NIST, 2008), P-value = Probability value of the non-parametric test for comparing the amounts of volatiles released by cultivated tomato, wild tomato, giant nightshade, marigold, and blackjack where significant values are in bold and means with different letters are significantly different at 5% probability level (P ≤ 0.05), nd = not detected, the symbol ( ɸ ) = Compounds confirmed with authentic standards.…”