Local conditions influence the reproductive strategies and pollen diet of a solitary cavity-nesting bee in a Mediterranean peri-urban environment

Local conditions influence the reproductive strategies and pollen diet of a solitary cavity-nesting bee in a Mediterranean peri-urban environment | 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 Local conditions influence the reproductive strategies and pollen diet of a solitary cavity-nesting bee in a Mediterranean peri-urban environment Martino Maggioni, Oana Catalina Moldoveanu, Massimo Martini, Felix Fornoff, and 7 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8723209/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Green areas in urban and peri-urban landscapes are increasingly recognized as important habitats for wild bees, but the extent to which species adjust their reproductive behavior to local conditions in these environments remains poorly studied. We studied the reproductive output, offspring's body size, sex allocation, and larval diet (assessed via pollen grain morphology and DNA metabarcoding) of the solitary bee Osmia caerulescens (Linnaeus, 1758) in a Mediterranean peri-urban environment using traps nest and local-scale environmental descriptors. Based on a total of 215 nest and 648 brood cells, females increased their reproductive output with greater floral resource availability and increasing openness of the habitat, but this was accompanied by a reduction in offspring body size (ITD) and a sex allocation skewed toward males. Together, these responses indicate a shift toward quantity-oriented reproductive strategies, in contrast to patterns reported for this species in agricultural systems. Pronounced among-site variation in pollen diet within a relatively restricted area further highlights the importance of local-scale resource landscapes in shaping these allocation strategies and, ultimately, population persistence. Our results show that the ecological value of urban habitats for solitary bees depends not only on the amount of floral resources available, but also on how local conditions influence species-specific reproductive responses. These findings highlight the value of species-specific reproductive analyses in abundant, functionally important solitary bees as a complementary approach to evaluating habitat quality at local scales in urban and peri-urban environments. Understanding how solitary bees adjust reproductive strategies to urban conditions is essential for supporting their conservation and long-term persistence in urban green spaces. Trap nest Osmiini urban pollinators body size sex allocation Solitary bees Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Full Text Additional Declarations No competing interests reported. Table 1 is available in the Supplementary Files section. Supplementary Files MaggionietalSupplementaryInformationSI1.docx MaggionietalSupplementaryInformationSI2.docx MaggionietalTable.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 15 Mar, 2026 Reviews received at journal 13 Mar, 2026 Reviews received at journal 20 Feb, 2026 Reviewers agreed at journal 16 Feb, 2026 Reviewers agreed at journal 06 Feb, 2026 Reviewers invited by journal 02 Feb, 2026 Editor assigned by journal 01 Feb, 2026 Submission checks completed at journal 30 Jan, 2026 First submitted to journal 28 Jan, 2026 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-8723209","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":581935733,"identity":"4e5d8e95-4a37-4851-9c3f-9e8b6708ac49","order_by":0,"name":"Martino Maggioni","email":"","orcid":"","institution":"University of Palermo","correspondingAuthor":false,"prefix":"","firstName":"Martino","middleName":"","lastName":"Maggioni","suffix":""},{"id":581935734,"identity":"03658497-1532-4618-bf10-5ac359b2dc07","order_by":1,"name":"Oana Catalina Moldoveanu","email":"","orcid":"","institution":"University of Florence","correspondingAuthor":false,"prefix":"","firstName":"Oana","middleName":"Catalina","lastName":"Moldoveanu","suffix":""},{"id":581935735,"identity":"1bfe95c2-eb2d-4aec-a8ad-d140cb54927a","order_by":2,"name":"Massimo Martini","email":"","orcid":"","institution":"University of Freiburg","correspondingAuthor":false,"prefix":"","firstName":"Massimo","middleName":"","lastName":"Martini","suffix":""},{"id":581935736,"identity":"7f033ff7-c81e-4791-83e6-1850b7da6876","order_by":3,"name":"Felix Fornoff","email":"","orcid":"","institution":"University of Freiburg","correspondingAuthor":false,"prefix":"","firstName":"Felix","middleName":"","lastName":"Fornoff","suffix":""},{"id":581935737,"identity":"314d8598-d551-4a8c-a896-e584bb35f419","order_by":4,"name":"Paolo Biella","email":"","orcid":"","institution":"University of Milano-Bicocca","correspondingAuthor":false,"prefix":"","firstName":"Paolo","middleName":"","lastName":"Biella","suffix":""},{"id":581935738,"identity":"d22184af-7b7f-40d2-b34b-7a4dbfa025c5","order_by":5,"name":"Andrea Galimberti","email":"","orcid":"","institution":"University of Milano-Bicocca","correspondingAuthor":false,"prefix":"","firstName":"Andrea","middleName":"","lastName":"Galimberti","suffix":""},{"id":581935739,"identity":"a566cc06-349e-4624-aaf7-3e63a72ad658","order_by":6,"name":"Matilde Massetti","email":"","orcid":"","institution":"University of Florence","correspondingAuthor":false,"prefix":"","firstName":"Matilde","middleName":"","lastName":"Massetti","suffix":""},{"id":581935740,"identity":"7e4d40cf-db38-4f09-8e98-4a3c047968fe","order_by":7,"name":"Giulia Guerri","email":"","orcid":"","institution":"National Research Council","correspondingAuthor":false,"prefix":"","firstName":"Giulia","middleName":"","lastName":"Guerri","suffix":""},{"id":581935741,"identity":"13f77f65-c8dc-4780-bddc-79d50b86389f","order_by":8,"name":"Gennaro Albini","email":"","orcid":"","institution":"National Research Council","correspondingAuthor":false,"prefix":"","firstName":"Gennaro","middleName":"","lastName":"Albini","suffix":""},{"id":581935742,"identity":"c4d09f02-6e4e-4668-8920-3c3d8f53db96","order_by":9,"name":"Marco Morabito","email":"","orcid":"","institution":"National Research Council","correspondingAuthor":false,"prefix":"","firstName":"Marco","middleName":"","lastName":"Morabito","suffix":""},{"id":581935743,"identity":"2e838995-4a64-4958-88ae-b86f25d7d962","order_by":10,"name":"Francesca Romana Dani","email":"data:image/png;base64,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","orcid":"","institution":"University of Florence","correspondingAuthor":true,"prefix":"","firstName":"Francesca","middleName":"Romana","lastName":"Dani","suffix":""}],"badges":[],"createdAt":"2026-01-28 16:09:35","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8723209/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8723209/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101475036,"identity":"a1c1514c-1c8a-4f8b-a259-d7253a0d9101","added_by":"auto","created_at":"2026-01-30 06:48:58","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":346331,"visible":true,"origin":"","legend":"\u003cp\u003eStudy area and location of the eight trap nest sampling sites near the city of Florence. Each circle represents a 250m buffer around the trap nest, within which land-cover composition was extracted from the National Land Cover Map (ISPRA 2023). Land-cover classes include artificial surfaces, tree cover, shrub cover, periodic and permanent grass cover, and water bodies. For all the analyses, periodic and permanent grass cover and shrub cover were merged into a single grass cover category (see Environmental features\u003cstrong\u003e \u003c/strong\u003esection). Among the eight sites, O. caerulescens was not detected at BSR. The basemap is derived from Google Satellite imagery.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8723209/v1/1c4b945bad36feda6cd4e1a1.jpg"},{"id":101751954,"identity":"cc8829a0-29f9-402a-8ba5-d9985d6972c0","added_by":"auto","created_at":"2026-02-03 10:24:32","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":68090,"visible":true,"origin":"","legend":"\u003cp\u003eThe number of brood cells per nest in O. caerulescensincreased with increasing Flower Index (A) and grass cover (B). Points represent observed nest-level values, with point size indicating the number of overlapping observations, and solid lines show negative binomial GLM predictions of marginal effects with 95% confidence intervals (shaded bands).\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8723209/v1/f7ba0930db6453fc2a146fe2.jpg"},{"id":101475038,"identity":"d779beac-6875-4798-8469-f729063795d6","added_by":"auto","created_at":"2026-01-30 06:48:58","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":129255,"visible":true,"origin":"","legend":"\u003cp\u003eO. caerulescens maternal investment declined with (A) increasing Flower Index and (B) increasing grass cover. (C) sex-specific maternal investment declined with increasing grass cover for females and was constant for males. Points represent nest-level values and solid lines Gaussian GLM predictions of marginal effects with 95% confidence intervals (shaded bands).\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8723209/v1/b71599b8d4750319bdf01381.jpg"},{"id":101475041,"identity":"75c92642-a462-4b7a-85b4-a66113d10a24","added_by":"auto","created_at":"2026-01-30 06:48:58","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":116172,"visible":true,"origin":"","legend":"\u003cp\u003eThe predicted proportion of female offspring in O. caerulescens increased with reed diameter (A), but declined with increasing Flower Index (B) and grass cover (C). Points represent observed nest-level proportions of females (jittered to reduce overlap), and solid lines show beta-binomial GLM predictions of marginal effects with 95% confidence intervals (shaded bands).\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8723209/v1/cf567854b24f81693fdf6e36.jpg"},{"id":101475040,"identity":"69d20995-90d4-4198-b931-9a6707f7d2ed","added_by":"auto","created_at":"2026-01-30 06:48:58","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":92781,"visible":true,"origin":"","legend":"\u003cp\u003eNMDS ordination (Bray–Curtis distance, stress = 0.079) of pollen composition collected by O. caerulescens across six study sites. Points represent individual brood-cell pollen samples, colored by site. Dashed hulls outline the multivariate extent of each site. Significant plant taxa (envfit, p ≤ 0.05) are shown as vectors, scaled for clarity, indicating their contribution to major compositional gradients. The ordination highlights clear site-level differences in pollen use, driven primarily by Fabaceae, Asteraceae, and Lamiaceae taxa.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8723209/v1/870322c76235f34ebdb8071b.jpg"},{"id":101755306,"identity":"f5e573e7-0c14-4191-8b24-1adc837e7e36","added_by":"auto","created_at":"2026-02-03 10:50:40","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1310928,"visible":true,"origin":"","legend":"","description":"","filename":"MaggionietalMainText.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8723209/v1_covered_7eb2c48e-b6c9-4972-aae8-c19ea445850a.pdf"},{"id":101475070,"identity":"e22e7bdc-4292-4666-812c-6ecd01bdec5d","added_by":"auto","created_at":"2026-01-30 06:49:14","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":508029904,"visible":true,"origin":"","legend":"","description":"","filename":"MaggionietalSupplementaryInformationSI1.docx","url":"https://assets-eu.researchsquare.com/files/rs-8723209/v1/ca7e6681b433f34c6b05d919.docx"},{"id":101475043,"identity":"34bacd49-8fc0-4827-abfc-f5bc56e9f901","added_by":"auto","created_at":"2026-01-30 06:48:58","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":18763,"visible":true,"origin":"","legend":"","description":"","filename":"MaggionietalSupplementaryInformationSI2.docx","url":"https://assets-eu.researchsquare.com/files/rs-8723209/v1/3b5de7fcfddad720093475d5.docx"},{"id":101752144,"identity":"baf120ad-18d3-4b91-a2df-9c27efc8b6ec","added_by":"auto","created_at":"2026-02-03 10:25:42","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":29270,"visible":true,"origin":"","legend":"","description":"","filename":"MaggionietalTable.docx","url":"https://assets-eu.researchsquare.com/files/rs-8723209/v1/1a86947094524e3e594555ea.docx"}],"financialInterests":"\u003cp\u003eNo competing interests reported.\u003c/p\u003e\n\u003cp\u003eTable 1 is available in the Supplementary Files section.\u003c/p\u003e","formattedTitle":"Local conditions influence the reproductive strategies and pollen diet of a solitary cavity-nesting bee in a Mediterranean peri-urban environment","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"urban-ecosystems","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ueco","sideBox":"Learn more about [Urban Ecosystems](https://www.springer.com/journal/11252)","snPcode":"11252","submissionUrl":"https://submission.nature.com/new-submission/11252/3","title":"Urban Ecosystems","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Trap nest, Osmiini, urban pollinators, body size, sex allocation, Solitary bees","lastPublishedDoi":"10.21203/rs.3.rs-8723209/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8723209/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Green areas in urban and peri-urban landscapes are increasingly recognized as important habitats for wild bees, but the extent to which species adjust their reproductive behavior to local conditions in these environments remains poorly studied. We studied the reproductive output, offspring's body size, sex allocation, and larval diet (assessed via pollen grain morphology and DNA metabarcoding) of the solitary bee Osmia caerulescens (Linnaeus, 1758) in a Mediterranean peri-urban environment using traps nest and local-scale environmental descriptors. Based on a total of 215 nest and 648 brood cells, females increased their reproductive output with greater floral resource availability and increasing openness of the habitat, but this was accompanied by a reduction in offspring body size (ITD) and a sex allocation skewed toward males. Together, these responses indicate a shift toward quantity-oriented reproductive strategies, in contrast to patterns reported for this species in agricultural systems. Pronounced among-site variation in pollen diet within a relatively restricted area further highlights the importance of local-scale resource landscapes in shaping these allocation strategies and, ultimately, population persistence. Our results show that the ecological value of urban habitats for solitary bees depends not only on the amount of floral resources available, but also on how local conditions influence species-specific reproductive responses. These findings highlight the value of species-specific reproductive analyses in abundant, functionally important solitary bees as a complementary approach to evaluating habitat quality at local scales in urban and peri-urban environments. Understanding how solitary bees adjust reproductive strategies to urban conditions is essential for supporting their conservation and long-term persistence in urban green spaces.","manuscriptTitle":"Local conditions influence the reproductive strategies and pollen diet of a solitary cavity-nesting bee in a Mediterranean peri-urban environment","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-30 06:48:52","doi":"10.21203/rs.3.rs-8723209/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-16T00:27:37+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-13T20:07:04+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-20T16:42:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"167146049477851971720697850575849756390","date":"2026-02-16T14:33:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"219231212140213332970818421381797883312","date":"2026-02-06T16:53:38+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-02T16:56:29+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-01T11:33:30+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-30T07:03:21+00:00","index":"","fulltext":""},{"type":"submitted","content":"Urban Ecosystems","date":"2026-01-28T15:12:47+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"urban-ecosystems","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ueco","sideBox":"Learn more about [Urban Ecosystems](https://www.springer.com/journal/11252)","snPcode":"11252","submissionUrl":"https://submission.nature.com/new-submission/11252/3","title":"Urban Ecosystems","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"15d975a5-193f-4f65-8b5d-a11a5079e543","owner":[],"postedDate":"January 30th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-16T02:10:18+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-30 06:48:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8723209","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8723209","identity":"rs-8723209","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}