Transformation of Internal Thoracic Structures of <i>Callobruchus maculatus</i> (Coleoptera: Bruchidae) from Larva to Adult

<i>Callobruchus maculatus</i> is a major quarantine pest of stored legumes in China. As a holometabolous insect, it lives inside the bean it burrows into in both its larval and pupal stages. This study utilized micro-CT and 3D reconstruction to document thoracic morphological transformat...

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Main Authors: Sipei Liu, Xiaokun Liu, Lijie Zhang, Xieshuang Wang, Xinying Zhang, Le Zong, Wenjie Li, Zhengzhong Huang, Xin Liu, Siqin Ge
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Insects
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Online Access:https://www.mdpi.com/2075-4450/16/3/324
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author Sipei Liu
Xiaokun Liu
Lijie Zhang
Xieshuang Wang
Xinying Zhang
Le Zong
Wenjie Li
Zhengzhong Huang
Xin Liu
Siqin Ge
author_facet Sipei Liu
Xiaokun Liu
Lijie Zhang
Xieshuang Wang
Xinying Zhang
Le Zong
Wenjie Li
Zhengzhong Huang
Xin Liu
Siqin Ge
author_sort Sipei Liu
collection DOAJ
description <i>Callobruchus maculatus</i> is a major quarantine pest of stored legumes in China. As a holometabolous insect, it lives inside the bean it burrows into in both its larval and pupal stages. This study utilized micro-CT and 3D reconstruction to document thoracic morphological transformation during larval and pupal stages. The multi-peak fitting of cranial width was applied to determine larval instars. The results indicate that the first-instar larvae bore into beans using prothoracic muscles and those connecting the head to the mesothorax. The second-instar larva possessed the highest number of thoracic muscles, likely correlating with peak boring activity. The prepupa and the initial pupa exhibited minimal musculature, suggesting larval muscle degradation prior to pupation. Muscles unique to prepupae might homologize with indirect flight muscles in pupae, implying that adult flight capability is determined in the final larval stage. The muscles of both larvae and pupae undergo changes in attachment site, shape and curvature throughout development. At the same time, changes also occur in the larval cuticle and pupal endoskeleton. During the larval stage, muscle growth and degradation occur simultaneously, influencing muscle volume. In the pupal stage, the progressive increase in both absolute and relative thoracic muscle volumes prepare the weevil for movement after emergence. Meanwhile, the other thoracic organs, including the gut, air sacs and nerves, also change during development.
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spelling doaj-art-a4e3db61b4d3461890f5944f64751bef2025-08-20T02:42:34ZengMDPI AGInsects2075-44502025-03-0116332410.3390/insects16030324Transformation of Internal Thoracic Structures of <i>Callobruchus maculatus</i> (Coleoptera: Bruchidae) from Larva to AdultSipei Liu0Xiaokun Liu1Lijie Zhang2Xieshuang Wang3Xinying Zhang4Le Zong5Wenjie Li6Zhengzhong Huang7Xin Liu8Siqin Ge9Key Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Chinese Academy of Sciences, Beijing 100101, ChinaKey Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Chinese Academy of Sciences, Beijing 100101, ChinaScience and Technology Research Center of China Customs, Beijing 100101, ChinaKey Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Chinese Academy of Sciences, Beijing 100101, ChinaKey Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Chinese Academy of Sciences, Beijing 100101, ChinaKey Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Chinese Academy of Sciences, Beijing 100101, ChinaKey Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Chinese Academy of Sciences, Beijing 100101, ChinaKey Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Chinese Academy of Sciences, Beijing 100101, ChinaDepartment of Medical Research the Ninth Medical Center Chinese PLA General Hospital, Beijing 100101, ChinaKey Laboratory of Animal Biodiversity Conservation and Integrated Pest Management, Chinese Academy of Sciences, Beijing 100101, China<i>Callobruchus maculatus</i> is a major quarantine pest of stored legumes in China. As a holometabolous insect, it lives inside the bean it burrows into in both its larval and pupal stages. This study utilized micro-CT and 3D reconstruction to document thoracic morphological transformation during larval and pupal stages. The multi-peak fitting of cranial width was applied to determine larval instars. The results indicate that the first-instar larvae bore into beans using prothoracic muscles and those connecting the head to the mesothorax. The second-instar larva possessed the highest number of thoracic muscles, likely correlating with peak boring activity. The prepupa and the initial pupa exhibited minimal musculature, suggesting larval muscle degradation prior to pupation. Muscles unique to prepupae might homologize with indirect flight muscles in pupae, implying that adult flight capability is determined in the final larval stage. The muscles of both larvae and pupae undergo changes in attachment site, shape and curvature throughout development. At the same time, changes also occur in the larval cuticle and pupal endoskeleton. During the larval stage, muscle growth and degradation occur simultaneously, influencing muscle volume. In the pupal stage, the progressive increase in both absolute and relative thoracic muscle volumes prepare the weevil for movement after emergence. Meanwhile, the other thoracic organs, including the gut, air sacs and nerves, also change during development.https://www.mdpi.com/2075-4450/16/3/324<i>Callobruchus maculatus</i>3D reconstructionmetamorphosisthoracic morphology
spellingShingle Sipei Liu
Xiaokun Liu
Lijie Zhang
Xieshuang Wang
Xinying Zhang
Le Zong
Wenjie Li
Zhengzhong Huang
Xin Liu
Siqin Ge
Transformation of Internal Thoracic Structures of <i>Callobruchus maculatus</i> (Coleoptera: Bruchidae) from Larva to Adult
Insects
<i>Callobruchus maculatus</i>
3D reconstruction
metamorphosis
thoracic morphology
title Transformation of Internal Thoracic Structures of <i>Callobruchus maculatus</i> (Coleoptera: Bruchidae) from Larva to Adult
title_full Transformation of Internal Thoracic Structures of <i>Callobruchus maculatus</i> (Coleoptera: Bruchidae) from Larva to Adult
title_fullStr Transformation of Internal Thoracic Structures of <i>Callobruchus maculatus</i> (Coleoptera: Bruchidae) from Larva to Adult
title_full_unstemmed Transformation of Internal Thoracic Structures of <i>Callobruchus maculatus</i> (Coleoptera: Bruchidae) from Larva to Adult
title_short Transformation of Internal Thoracic Structures of <i>Callobruchus maculatus</i> (Coleoptera: Bruchidae) from Larva to Adult
title_sort transformation of internal thoracic structures of i callobruchus maculatus i coleoptera bruchidae from larva to adult
topic <i>Callobruchus maculatus</i>
3D reconstruction
metamorphosis
thoracic morphology
url https://www.mdpi.com/2075-4450/16/3/324
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