The tsetse fly Glossina fuscipes fuscipes (Diptera: Glossina) harbours a surprising diversity of bacteria other than symbionts

Abstract

Three different bacterial species are regularly described from tsetse flies. However, no broad screens have been performed to investigate the existence of other bacteria in this medically and agriculturally important vector insect. Utilising both culture dependent and independent methods we show that Kenyan populations of Glossina fuscipes fuscipes harbour a surprising diversity of bacteria. Bacteria were isolated from 72% of flies with 23 different bacterial species identified. The Firmicutes phylum dominated with 16 species of which seven belong to the genus Bacillus. The tsetse fly primary symbiont, Wigglesworthia glossinidia, was identified by the culture independent pathway. However, neither the secondary symbiont Sodalis nor Wolbachia was detected with either of the methods used. Two other bacterial species were identified with the DNA based method, Bacillus subtilis and Serratia marcescens. Further studies are needed to determine how tsetse flies, which only ever feed on vertebrate blood, pick up bacteria and to investigate the possible impact of these bacteria on Glossina longevity and vector competence.

Interwoven Biology of the Tsetse Holobiont

“…It should also be noted that recent field studies have found an unexpected diversity within the microbial community of tsetse which is dependent on host species and geographic region (49,51). Differences in abiotic conditions and food sources may influence the composition of these transient microbial communities (49,94).…”

“…Tsetse can also harbor the Alphaproteobacteria Wolbachia (44), a facultative parasite infecting many different invertebrates (45,46), which is typically restricted to the reproductive organs (47,48). Field studies report a more complex diversity in adult flies (49)(50)(51), although these microbes are believed to be transient in nature. The tsetse holobiont provides opportunities to examine evolutionary aspects associated with adapting to microbial coresidence, as Wigglesworthia and Sodalis have drastically different times of establishment (10,52).…”

“…Evidence lies in its ability to be cultured (64), providing a tremendous benefit for empirical analyses, wide tsetse tissue tropism with both intra-and extracellular localization (41,48), lack of coevolution with host species (10), and stochastic presence in the field (49,51,65). Similar to Wigglesworthia, Sodalis is vertically transmitted through the maternal milk glands (40,41).…”

“Wigglesworthia morsitans” Folate (Vitamin B 9 ) Biosynthesis Contributes to Tsetse Host Fitness

“…(17), the commensal Sodalis glossinidius (18), and members of the parasitic genus Wolbachia (19,20). Field studies report a more complex and diverse adult microbiota (21)(22)(23)(24), although the majority is believed to be transient in nature. Enhanced knowledge of tsetse symbioses may provide novel and specific avenues for vector control, such as through paratransgenesis, in which symbionts deliver effector molecules that interfere with parasite development (25,26), or the use of a novel class of pesticides aimed at disrupting pivotal symbiont-mediated tsetse fly metabolic processes.…”

Arsenophonus and Sodalis Symbionts in Louse Flies: an Analogy to the Wigglesworthia and Sodalis System in Tsetse Flies

“…Both symbionts are vertically transmitted via milk glands (7,9,10) and are presumed to compensate for the nutritionally unbalanced blood diet (11)(12)(13)(14)(15). This highly specific microbiome of tsetse flies is usually accompanied by reproductive manipulators from the genus Wolbachia (16) and a diversity of other transient bacteria of unknown relationship to the host (17,18). In contrast to Glossinidae, the family Hippoboscidae is a species-rich, highly diversified, and cosmopolitan group feeding on mammals and birds (4).…”