Less cooperative belowground plant mutualists negatively affect aboveground herbivore growth and survival

Less cooperative belowground plant mutualists negatively affect aboveground herbivore growth and survival | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Less cooperative belowground plant mutualists negatively affect aboveground herbivore growth and survival Annaliese Wargin, Katy Heath, Jennifer Lau, Adam Dolezal, Alexandra Harmon-Threatt This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8745055/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Resource mutualists like nitrogen (N)-fixing rhizobia can improve the nutrition of plants available to higher trophic levels. However, there is substantial intraspecific variation in mutualist quality. How this variation in mutualist quality affects higher trophic levels, such as herbivores, is unclear, as high-quality resource mutualists could increase both leaf nutrient content, which should improve herbivore growth, but also plant chemical defenses, which are expected to inhibit herbivore growth. We evaluated the effect of rhizobium strains of varying mutualist quality on the survival and development of a generalist insect herbivore, the beet armyworm (Spodoptera exigua), reared on alsike clover (Trifolium hybridum). We inoculated T. hybridum with cooperative (“high-quality”) and less cooperative (“low-quality”) rhizobia strains, measured plant growth, nutrients, and metabolites, and fed the leaves to S. exigua. We found that high-quality rhizobium strains significantly improved S. exigua survival, but also increased development time compared to low-quality strains. Furthermore, some developmental traits, such as pupal weight and adult wing area, increased in high-quality treatments. Inoculation with strains of varying quality impacted T. hybridum nutrition and phytochemistry, suggesting that both could mediate herbivore responses to mutualist quality. The effects of rhizobium genetic variation on herbivores exceeded the effects of N-fertilization alone: S. exigua fed leaves from uninoculated, fertilized plants had decreased survival compared to caterpillars fed leaves from high-quality partners, implying that N deposition into ecosystems does not fully replace benefits provided by rhizobia to higher trophic levels. Mutualism herbivory plant defense nitrogen symbiosis Full Text Supplementary Files Supplement1WarginOecologia.pdf Supplement2WarginOecologia.pdf Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8745055","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":596551515,"identity":"cb0eefc0-961d-4d2a-841e-df5e4f39a020","order_by":0,"name":"Annaliese 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However, there is substantial intraspecific variation in mutualist quality. How this variation in mutualist quality affects higher trophic levels, such as herbivores, is unclear, as high-quality resource mutualists could increase both leaf nutrient content, which should improve herbivore growth, but also plant chemical defenses, which are expected to inhibit herbivore growth. We evaluated the effect of rhizobium strains of varying mutualist quality on the survival and development of a generalist insect herbivore, the beet armyworm (Spodoptera exigua), reared on alsike clover (Trifolium hybridum). We inoculated T. hybridum with cooperative (“high-quality”) and less cooperative (“low-quality”) rhizobia strains, measured plant growth, nutrients, and metabolites, and fed the leaves to S. exigua. We found that high-quality rhizobium strains significantly improved S. exigua survival, but also increased development time compared to low-quality strains. Furthermore, some developmental traits, such as pupal weight and adult wing area, increased in high-quality treatments. Inoculation with strains of varying quality impacted T. hybridum nutrition and phytochemistry, suggesting that both could mediate herbivore responses to mutualist quality. 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