Abstract
After leaving their hosts, the larvae of endoparasitic braconid wasps pupate in cocoons. To determine their investment in cocoon silk, the dry weight of newly emerged wasps and that of the empty cocoons were measured for three gregarious braconid species of slightly different sizes: Glyptapanteles liparidis (Bouche), Cotesia glomerata (L.) and Cotesia kariyai (Watanabe) (Hymenoptera: Braconidae, Microgastrinae). These braconids form clusters of cocoons of different types. Glyptapanteles liparidis is significantly larger than either of the Cotesia species, and C. kariyai is the smallest. The ratio of the weight of cocoon silk to the total weight of cocoon silk, wasp body, cast cuticle and meconium is smaller for small species than large species. Small species econo- mise on their use of silk by aggregating cocoons and can therefore invest a larger fraction of their resources in adult body mass. Moreover, the larvae of the smallest species, C. kariyai, additionally reduce their use of silk by constructing a communal airy silk layer beneath which the individual cocoons are formed.
Highlights
Some insects pupate in cocoons, which protect the pupae from weather and natural enemies
The weight of G. liparidis was not influenced by the number of wasps (= cocoons) in a cluster (r = 0.127, ns)
The silk weights per cocoon were lower for larger clusters (C. glomerata, r = –0.550, p < 0.01; C. kariyai, r = –0.819, p < 0.01)
Summary
Some insects pupate in cocoons, which protect the pupae from weather and natural enemies. Robust cocoons of the tasar silkworm Antheraea mylitta (Drury) (Lepidoptera: Saturniidae) protect the pupae from desiccation during long periods of low humidity and high temperatures (Tripathi & Singh, 1983). The cocoon of the soybean pod borer Leguminivora glycinivorella (Matsumura) (Lepidoptera: Tortricidae) protects overwintering pupae from drowning when the soil becomes waterlogged (Sakagami et al, 1985). A tough cocoon requires a large investment in terms of silk. The expectation is that small individuals will invest proportionally more in cocoon silk than large individuals. In this respect, the relation between body size and proportional investment in cocoon silk is worthy of study
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
