Do tsetse flies only feed on blood?

Abstract

Tsetse flies (Diptera: Glossinidae) are the vectors of trypanosomes causing sleeping sickness in humans, and nagana (animal trypanosomosis) in domestic animals, in Subsaharan Africa. They have been described as being strictly hematophagous, and transmission of trypanosomes occurs when they feed on a human or an animal. There have been indications however in old papers that tsetse may have the ability to digest sugar. Here we show that hungry tsetse (Glossina palpalis gambiensis) in the lab do feed on water and on water with sugar when no blood is available, and we also show that wild tsetse have detectable sugar residues. We showed in laboratory conditions that at a low concentration (0.1%) or provided occasionally (0.1%, 0.5%, 1%), glucose had no significant impact on female longevity and fecundity. However, regular provision of water with 1% glucose increased the mortality and reduced the fecundity of female G. p. gambiensis. The proportion of wild tsetse caught by traps, which have detectable sugar residue in their midgut varied between 5 and 10% according to species (p<10(-3)) and sex, with more females being found with sugar residues than males (p<10(-3)). We also observed a higher frequency of sugar residues in the dry season than in the rainy season (p<10(3)). The infection status did not affect the frequency of sugar residues found (p=0.65), neither did age (p=0.23). These observations represent a fundamental change in our knowledge of this insect vector. They open the way for further research on the field to know more on tsetse feeding behavior regarding other sources of meal than blood, in particular with plants, and may constitute future new means of controlling this vector of neglected tropical diseases.

Intestinal Bacterial Communities of Trypanosome-Infected and Uninfected Glossina palpalis palpalis from Three Human African Trypanomiasis Foci in Cameroon

“…Nevertheless, further independent studies should be undertaken to confirm the finding. An alternative explanation could account for the complexity of the microbiota as it was recently reported, that is, tsetse flies are not strictly hematophagous; they can occasionally feed on nectar from a broad range of plants growing within their different ecological environments, and, thus, may ingest bacteria colonizing this nutriment (Colman et al, 2012 ; Solano et al, 2015 ). Such effect of diet differences and their links to environmental conditions, on bacteriome community structure of insects has been documented by Colman et al ( 2012 ).…”

Challenging the Wigglesworthia, Sodalis, Wolbachia symbiosis dogma in tsetse flies: Spiroplasma is present in both laboratory and natural populations

“…There is now evidence that Gpg flies deprived of a blood meal can feed on water or sugar water, and that sugar residues are detectable in wild-caught flies 66 . Therefore, it is possible that these previously unrecognized feeding habits could be a source of environmental microbes, and could be the origin of the low-frequency high-abundance infections observed in multiple individuals in this study.…”

Neemazal ® as a possible alternative control tool for malaria and African trypanosomiasis?

“…Unlike mosquitoes, tsetse flies readily fed on NeemAzal ®-treated blood-meals, even at 2000 μg/ml corresponding to 656 μg/ml of azadirachtin A. Because tsetse flies are exclusively hematophageous insects (but see [ 45 ]) and given the fact that blood is not a risky source in terms of presence of toxic components, it is plausible that Glossina flies have not evolved chemo-receptors for scrutinizing potentially toxic elements in their alimentary source. In this study NA impact on vector feeding behaviour was evaluated after a single administration of the neem product.…”