Habitat type and host grazing regimen influence the soil microbial diversity and communities within potential biting midge larval habitats

Authors: NEUPANE, SARASWOTI - Kansas State University; Davis, Travis; Nayduch, Dana; McGregor, Bethany

Submitted to: Environmental Microbiome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2022
Publication Date: 1/19/2023
Citation: Neupane, S., Davis, T.M., Nayduch, D., McGregor, B.L. 2023. Habitat type and host grazing regimen influence the soil microbial diversity and communities within potential biting midge larval habitats. Environmental Microbiome. 18(1):5-21. https://doi.org/10.1186/s40793-022-00456-8.
DOI: https://doi.org/10.1186/s40793-022-00456-8

Interpretive Summary: Biting midges are small flies that can spread a variety of diseases to animals. Immature midges live in soil environments right at the edge of water bodies, but there are many things we don't currently know about these habitats, such as how microbes present in these habitats may be related to midge populations. In this study, we collected mud from pond and spring habitats associated with either animal disturbed (bison or cattle grazed) or undisturbed (ungrazed) environments. From these samples, we studied what microbes were present, which midge species emerged, and properties of the soil. We found that habitat and grazing type impacted the microbes that were present in the samples. Midges were found more frequently in grazed sites than ungrazed sites, tended to increase as soil characteristics like total carbon, total nitrogen, and organic matter decreased, and had different responses to the presence of different microbial groups. These results can help us identify key characteristics of midge larval habitats that can help with control of midges and midge-borne diseases in the future.

Technical Abstract: Background: Biting midges (Culicoides spp.) are important vectors of diverse microbes such as viruses, protozoa, and nematodes that cause diseases in wild and domestic animals. However, little is known about the role of microbial communities in midge larval habitat utilization in the wild. In this study, we characterized microbial communities (bacterial, protists, fungal and metazoa) in soils from disturbed (bison and cattle grazed) and undisturbed (non-grazed) pond and spring potential midge larval habitats. We evaluated the influence of habitat and grazing disturbance and their interaction on microbial communities, diversity, presence of midges, and soil properties. Results: Bacterial, protistan, fungal and metazoan community compositions were significantly influenced by habitat and grazing type. Irrespective of habitat and grazing type, soil communities were dominated by phyla Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Proteobacteria (Bacteria); Apicomplexa, Cercozoa, Ciliophora, Ochrophyta (Protists); Chytridiomycota, Cryptomycota (Fungi) and Nematoda, Arthropoda (Metazoa). The relative abundance of Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Proteobacteria, Verrucomicrobia (Bacteria); Apicomplexa, Lobosa (Protists); Ascomycota, Blastomycotina, Cryptomycota (Fungi); and Platyhelminthes (Metazoa) were significantly affected by grazing type. Of note, midge prevalence was higher in grazed sites (67 – 100%) than non-grazed (25%). Presence of midges in the soil was negatively correlated with bacterial, protistan, fungal and metazoan beta diversities and metazoan species richness but positively correlated with protistan and fungal species richness. Moreover, total carbon (TC), nitrogen (TN) and organic matter (OM) were negatively correlated with the presence of midges and relative abundances of unclassified Solirubrobacterales (Bacteria), Chlamydomonadales (Protists) but positively with Proteobacteria and unclassified Burkholderiales (Bacteria). Conclusions: Habitat and grazing type shaped the soil bacterial, protistan, fungal and metazoan communities, their compositions and diversities as well as presence of midges. Soil properties (TN, TC, OM) also influenced soil microbial communities, diversities and the presence of midges. Prevalence of midges mainly in grazed sites indicates that midges prefer to breed and shelter in a habitat with abundant hosts, probably due to greater accessibility of food (blood meals). These results provide a first glimpse into the microbial communities, soil properties and prevalence of midges in suspected midge larval habitats at a protected natural prairie site.