Species Identity, Life History, and Geographic Distance Influence Gut Bacterial Communities in Lab-Reared and European Field-Collected Culicoides Biting midges

Abstract

Bacteria are part of the insect gut system and influence many physiological traits of their host. Gut bacteria may even reduce or block the transmission of arboviruses in several species of arthropod vectors. Culicoides biting midges are important arboviral vectors of several livestock and wildlife diseases, yet limited information is available on their gut bacterial communities. Addressing this gap will help inform how these communities can be manipulated and ultimately used as novel tools to control pathogens. To assess how bacterial communities change during the life stages of lab-reared C. nubeculosus and C. sonorensis, endosymbiotic bacteria were identified using Illumina sequencing of 16S rRNA and taxonomically characterised. Analyses were conducted to determine how gut bacterial communities in adults are influenced by species identity and geographic distance among biting midge populations. Communities of the two lab-reared Culicoides species significantly changed after pupation and with maturation into 6-day-old adults. Pseudomonas, Burkholderiaceae and Leucobacter bacteria were part of a core community that was trans-stadially transmitted and found throughout their life cycle. Among field-collected biting midges, the bacterial communities were unique for almost each species. Cardinium, Rickettsia and Wolbachia were some of the most abundant bacteria in midges collected from wetlands. Only Pseudomonas was present in high relative abundance in all field-collected species. In this study, species identity, as well as geographic distance, influenced the gut bacterial communities and may partly explain known inter- and intra-species variability in vector competence. Additionally, stably associated bacterial species could be candidates for paratransgenic strategies to control vector-borne pathogens.

In vitro biochemical characterization and identification of hemolytic bacteria associated with life history of Culicoides peregrinus (Diptera: Ceratopogonidae), a vector of bluetongue virus

“…B. cereus was also found in field-collected males and females (nulliparous, parous, and post-oviposited) of C. peregrinus implying their possible role not only in blood meal digestion. Based on the studies of Möhlmann et al (2021), Bacillus sp. formed core microbiota of the biting midges and may be associated with vector physiology.…”

“…In our study, pupae and newly emerged adults had a similar bacterial composition, however, the number of species in the gut bacteria of newly emerged adults and field-collected males and nulliparous females were varied as present status of feeding habitat of field-collected adults were unknown and microbial shifts happened based on their dietary regime. Due to adults feeding on carbohydrates, bacteria utilizing them flourish concomitantly, which may lower bacterial species diversity or alter microbial structure within their midgut (Möhlmann et al 2021).…”

Bacterial Communities in the Feces of Laboratory Reared Gampsocleis gratiosa (Orthoptera: Tettigoniidae) across Different Developmental Stages and Sexes

“…The dietary change in different developmental stages played a substantial role in shaping bacterial communities of holometabolic insects [28,59,[76][77][78][79]. For example, the bacterial diversity of Chironomus transvaalensis declines as it evolves from egg mass to adult, while the highest richness was observed in the pupal stage [60].…”

Biting Midges (Diptera: Ceratopogonidae) as Vectors of Viruses

“…Studies on the microbiota of Culicoides biting midges are scarce, mainly restricted to the bacterial midgut fauna, and differentiation, in the best case, to the genus level [183][184][185][186]. A few studies exist on the virome of Culicoides species [187][188][189][190].…”