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Seasonal Dynamics Without Reset: Core Microbiota Stability Across Development in a Gall-Dwelling Weevil
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School of Life Sciences, Qufu Normal University, Qufu 273165, China
2
Mingguangsi Forest Farm, Pingyi County, Linyi 273300, China
*
Authors to whom correspondence should be addressed.
Insects 2026, 17(6), 544; https://doi.org/10.3390/insects17060544 (registering DOI)
Submission received: 27 March 2026
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Revised: 21 May 2026
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Accepted: 21 May 2026
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Published: 23 May 2026
(This article belongs to the Section Insect Ecology, Diversity and Conservation)
Simple Summary
Insects often depend on associated bacteria for nutrition, development, and environmental adaptation, but these communities may change during growth. We studied this process in Coccotorus beijingensis, a gall-dwelling weevil whose larvae and pupae develop inside enclosed plant tissue. We found that the bacterial community changed across months and developmental stages, but its core members remained stable. A dominant symbiotic bacterium persisted throughout development, whereas other bacterial groups varied seasonally. Unlike some other holometabolous insects, this species showed no clear microbial reset during metamorphosis. These results improve our understanding of insect–microbe interactions and suggest that the closed gall environment may help maintain a stable core microbiota, with potential value for future pest management.
Abstract
Coccotorus beijingensis is a typical gall-inducing insect whose larvae complete their development within enclosed galls, providing a unique model for investigating host–microbe symbiosis. This study aimed to characterize the dynamic succession of the symbiotic microbiota in C. beijingensis across the larval stage (April–August) and pupal stage (September). Using high-throughput 16S rRNA gene sequencing, we performed a systematic analysis of monthly collected samples spanning the larval and pupal stages. The results revealed significant temporal variation in the structure of the larval microbial community. Bacillota and Bacteroidota were the dominant bacterial phyla throughout development. Although non-core bacterial groups, such as Pseudomonadota, showed pronounced seasonal fluctuations, no clear microbial reset was observed during metamorphosis. Exploratory PICRUSt2-based functional prediction suggested that the predicted metabolic potential of the microbiota may vary across development, with pathways related to carbohydrate metabolism, amino acid metabolism, and energy metabolism showing higher predicted representation during the middle larval stages. Overall, this study demonstrates that, within the confined gall microhabitat, larval development and seasonal dynamics jointly drive the temporal restructuring and functional adaptation of the microbial community. These findings provide new insights into the symbiotic mechanisms of holometabolous insects and their associated microbiota.
