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Urban habitat fragmentation and floral resources shape the occurrence of gut parasites in two bumblebee species
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  • Nicola Tommasi,
  • Beatrice Colombo,
  • Emiliano Pioltelli,
  • Paolo Biella,
  • Maurizio Casiraghi,
  • Andrea Galimberti
Nicola Tommasi
University of Milan–Bicocca

Corresponding Author:[email protected]

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Beatrice Colombo
University of Milan–Bicocca
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Emiliano Pioltelli
University of Milan–Bicocca
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Paolo Biella
University of Milan–Bicocca
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Maurizio Casiraghi
University of Milan-Bicocca
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Andrea Galimberti
University of Milan-Bicocca
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Urbanization and the expansion of human activities foster radical ecosystem changes with cascading effects also involving host-pathogen interactions. Urban pollinator insects face several stressors related to landscape and local scale features such as green habitat loss, fragmentation, and availability reduction of floral resources with unpredictable effects on parasite transmission. Furthermore, beekeeping may contribute to the spread of parasites to wild pollinators by increasing the number of parasite hosts. Here we used DNA-based diagnostics tools to evaluate how the occurrence of parasites, namely microsporidians (Nosema spp.), trypanosomatids (Crithidia spp.) and neogregarines (Apicystis bombi), is shaped by the above-mentioned stressors in two bumblebee species (i.e, Bombus terrestris and B. pascuorum). Infection rates of the two species were different and generally higher in B. terrestris. Moreover, they showed different responses towards the same ecological variables, possibly due to differences in body size and foraging habits supposed to affect their susceptibility to parasite infection. The probability of infection was found to be reduced in B. pascuorum by green habitat fragmentation, while increased along with floral resource availability. Unexpectedly, B. terrestris had a lower parasite richness nearby apiaries probably because parasites are prone to be transmitted among the most abundant species. Our finding supports the need to design proper conservation measures based on species-specific knowledge, as suggested by the variation in the parasite occurrence of the two species. Moreover, conservation policies aiming at safeguarding pollinators through flower planting should consider the indirect effects of these measures for parasite transmission together with pollinator biodiversity issues.
13 Apr 2023Submitted to Ecology and Evolution
15 Apr 2023Submission Checks Completed
15 Apr 2023Assigned to Editor
17 Apr 2023Reviewer(s) Assigned
27 Apr 2023Review(s) Completed, Editorial Evaluation Pending
24 May 2023Editorial Decision: Revise Minor
19 Jun 20231st Revision Received
20 Jun 2023Review(s) Completed, Editorial Evaluation Pending
20 Jun 2023Submission Checks Completed
20 Jun 2023Assigned to Editor
30 Jun 2023Editorial Decision: Accept