Microbial communities associated with stable fly (Diptera: Muscidae) larvae and their developmental substrates

Authors: Scully, Erin; Friesen, Kristina; Wienhold, Brian; Durso, Lisa

Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2016
Publication Date: 1/11/2017
Citation: Scully, E.D., Friesen, K.M., Wienhold, B.J., Durso, L.M. 2017. Microbial communities associated with stable fly (Diptera: Muscidae) larvae and their developmental substrates. Annals of the Entomological Society of America. 110(1):61-72. doi:10.1093/aesa/saw087.

Interpretive Summary: Stable flies are major pests of pasture and feedlot cattle. As with many other insect species, interactions with bacteria are essential for development of stable flies. However, little information is available regarding what types of microbes colonize stable flies and how food source influences the types of microbes associated with these flies. In this study, the bacterial and fungal composition of the bacterial and fungal communities of flies and their corresponding food substrates was explored. While food substrate had a moderate influence on the types of microbes found associated with the flies, there were some bacterial and fungal species that were associated exclusively with stable flies, indicating that there are several fungal and bacterial taxa persistently associated with flies and may be important symbionts and major contributors to developmental, digestive, and other physiological processes. In addition, several potential pathogens detected in food substrates were also found associated with stable flies, indicating that they could carry pathogens and pose significant risks to both human and animal health. This study represents one of the first in-depth analyses of the microbial community associated with stable flies and their food substrates and provides potential management implications. For example, pathogens in food substrates can be picked up and moved to different environments, suggesting that they may be important vehicles of disease for humans and cattle. Therefore, care needs to be taken to ensure cleanliness of calf bedding where flies commonly feed and develop. In addition, the identification of potential symbionts persistently associated with stable flies represent targets for controlling these pests.

Technical Abstract: Bacteria are essential for stable fly (Stomoxys calcitrans (L.)) larval survival and development, but little is known about the innate microbial communities of stable flies, and it is not known if their varied dietary substrates influence their gut microbial communities. This investigation utilized 454 sequencing to characterize and compare the bacterial and eukaryotic microbial communities in stable fly larvae and their developmental substrates. The microbial community of the third-instar stable fly larvae is unambiguously distinct from the microbial community of the supporting substrate, with bacterial communities from larvae reared on different substrates more similar to each other than to the communities from their individual supporting substrates. Bacterial genera that were more abundant proportionally in larvae compared to their substrates were Erysipelothrix, Dysgonomonas, Ignatzschineria Gammaproteobacteria), and Campylobacter (Epsilonprotobacteria). The alphaproteobacteria Devosia, Brevundimonas, Sphingopyxix, and Paracoccus were more abundant proportionally in field substrates compared to their larvae. The main genera responsible for differences between the positive and negative field substrates were Dysgonomonas and Proteiniphilum. In contrast to Dysgonomonas, Proteiniphilum was more abundant in substrate than in the larvae. A large number of sequences were assigned to an unclassified Alveolata in larvae and their substrate. Microscopy validated these findings and a previously undescribed gregarine (phylum Apicomplexa, class Conoidasida) was identified in stable fly larvae and adults.