Patterns of microbiome composition vary across spatial scales in a specialist insect

Authors: PADDOCK, KYLE - University Of Missouri; FINKE, DEBORAH - University Of Missouri; KIM, KYUNG SEOK - Iowa State University; Sappington, Thomas; Hibbard, Bruce

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2022
Publication Date: 6/2/2022
Citation: Paddock, K.J., Finke, D.L., Kim, K., Sappington, T.W., Hibbard, B.E. 2022. Patterns of microbiome composition vary across spatial scales in a specialist insect. Frontiers in Microbiology. 13. Article 898744. https://doi.org/10.3389/fmicb.2022.898744.
DOI: https://doi.org/10.3389/fmicb.2022.898744

Interpretive Summary: Animals host bacteria living inside them as communities of multiple species (called the "microbiome") which can vary based on many factors. Of many possible causes determining microbiome composition, host evolutionary history, host diet, and local environment are the most important. How these factors interact across spatial scales is not well understood. Here we seek to identify the main influences on microbiome composition in two closely related specialist insects, the western corn rootworm (WCR) and northern corn rootworm (NCR), by analyzing the bacterial communities of adults collected from their obligate host plant, corn, across several geographic locations. We found that bacterial communities of WCR and NCR differ despite these species being highly adapted to the same host plant. Wild beetle microbiomes were also influenced by the collection location. Correlations of geographic distance between sites with WCR bacterial community composition revealed different patterns at different spatial scales. Community similarity decreased with increased geographic distance at smaller spatial scales (~25 km between nearest sites). At broad spatial scales (>200 km), community composition was not correlated with distances between sites, but instead reflected the historical invasion path of WCR across the United States. These results suggest bacterial communities are structured directly by adult dispersal dynamics at small, regional spatial scales, while landscape-level genetic or environmental differences may drive community composition across broad spatial scales in this specialist insect.

Technical Abstract: Microbial communities associated with animals vary based on both intrinsic and extrinsic factors. Of many possible determinants affecting microbiome composition, host phylogeny, host diet, and local environment are the most important. How these factors interact across spatial scales is not well understood. Here we seek to identify the main influences on microbiome composition in two closely related specialist insects, the western corn rootworm (WCR; Diabrotica virgifera virgifera) and northern corn rootworm (NCR; D. barberi), by analyzing the bacterial communities of adults collected from their obligate host plant, corn (Zea mays), across several geographic locations. We found that bacterial communities of WCR and NCR differ despite these species being highly adapted to the same host plant. Wild beetle microbiomes were also influenced by the collection location. Correlations of geographic distance between sites with WCR bacterial community composition revealed different patterns at different spatial scales. Community similarity decreased with increased geographic distance at smaller spatial scales (~25 km between nearest sites). At broad spatial scales (>200 km), community composition was not correlated with distances between sites, but instead reflected the historical invasion path of WCR across the United States. These results suggest bacterial communities are structured directly by adult dispersal dynamics at small, regional spatial scales, while landscape-level genetic or environmental differences may drive community composition across broad spatial scales in this specialist insect.