Studies on the cocoon of the oriental moth, Monema (Cnidocampa) flavescens, (lepidoptera:limacodidae). III. Structure and composition of the cocoon in relation to hardness.

象二郎, 石井; 民夫, 井口; 純, 金沢; 長次郎, 富沢

doi:10.1303/jjaez.28.269

Cited by 8 publications

(7 citation statements)

References 2 publications

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“…As known, considerable number of insect species from Coleoptera, Lepidoptera, Hymenoptera and Neuroptera [ 10 – 14 ] were able to spinning and cocooning. The mature insect larva usually use silk or silk embedded with surrounding materials to construct cocoons, such as the silk cocoon of silkworm Bombyx mori [ 11 ] and mixed cocoon of Cnidocampa flavescens Walker [ 15 ]. After the pupa metamorphosing into adult, how the adult breaks out of the cocoon to complete the generational development becomes a matter.…”

Section: Introductionmentioning

confidence: 99%

Cocoonase is indispensable for Lepidoptera insects breaking the sealed cocoon

et al. 2020

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Many insects spin cocoons to protect the pupae from unfavorable environments and predators. After emerging from the pupa, the moths must escape from the sealed cocoons. Previous works identified cocoonase as the active enzyme loosening the cocoon to form an escape-hatch. Here, using bioinformatics tools, we show that cocoonase is specific to Lepidoptera and that it probably existed before the occurrence of lepidopteran insects spinning cocoons. Despite differences in cocooning behavior, we further show that cocoonase evolved by purification selection in Lepidoptera and that the selection is more intense in lepidopteran insects spinning sealed cocoons. Experimentally, we applied gene editing techniques to the silkworm Bombyx mori, which spins a dense and sealed cocoon, as a model of lepidopteran insects spinning sealed cocoons. We knocked out cocoonase using the CRISPR/Cas9 system. The adults of homozygous knockout mutants were completely formed and viable but stayed trapped and died naturally in the cocoon. This is the first experimental and phenotypic evidence that cocoonase is the determining factor for breaking the cocoon. This work led to a novel silkworm strain yielding permanently intact cocoons and provides a new strategy for controlling the pests that form cocoons.

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Section: Introductionmentioning

confidence: 99%

Cocoonase is indispensable for Lepidoptera insects breaking the sealed cocoon

et al. 2020

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“…Typically used in cocoons, this class of materials consists of a silk fibroin protein thread of up to 1 km long coated with sericin proteins acting as a resin/matrix glue ( Chen et al, 2010b ). This non-woven composite structure ( Chen et al, 2010a ) regulates gas flow and humidity ( Danks, 2004 ; Horrocks et al, 2013 ; Roy et al, 2012 ), as well as protecting the encased pupae from predation ( Ishii et al, 1984 ), micro-organisms ( Franceschi and Nakata, 2005 ) and the environment ( Chen et al, 2012b ). Silkworms produce cocoons with a broad variety of morphologies and architectures, ranging in porosity from loose meshes to full shells, with or without an exit opening ( Chen et al, 2012c ).…”

Section: Introductionmentioning

confidence: 99%

Identification and classification of silks using infrared spectroscopy

Boulet-Audet

Vollrath

Holland

2015

Journal of Experimental Biology

107

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Lepidopteran silks number in the thousands and display a vast diversity of structures, properties and industrial potential. To map this remarkable biochemical diversity, we present an identification and screening method based on the infrared spectra of native silk feedstock and cocoons. Multivariate analysis of over 1214 infrared spectra obtained from 35 species allowed us to group silks into distinct hierarchies and a classification that agrees well with current phylogenetic data and taxonomies. This approach also provides information on the relative content of sericin, calcium oxalate, phenolic compounds, poly-alanine and poly(alanine-glycine) β-sheets. It emerged that the domesticated mulberry silkmoth Bombyx mori represents an outlier compared with other silkmoth taxa in terms of spectral properties. Interestingly, Epiphora bauhiniae was found to contain the highest amount of β-sheets reported to date for any wild silkmoth. We conclude that our approach provides a new route to determine cocoon chemical composition and in turn a novel, biological as well as material, classification of silks.

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“…Parasa lepida cocoons are covered with a dark gray silk sheet that contains bark tissue, which the larvae ingest from nearby and regurgitate; this greatly enhances the level of crypsis, but not toughness. In contrast, the hard cocoon of M. flavescens is made from a fine silk net compactly filled with sclerotized protein (β-alanine) (Ishii et al 1984), which is contained in bulk in the insect cuticle (Hackman 1974). However, this does not enhance crypsis.…”

Section: Discussionmentioning

confidence: 99%

“…morphological armor) (Fig. 1a-f), because they are easily detectable without a cryptic shell but have the hardest cocoons among all Japanese insect species (Ishii et al 1984). Moreover, for the first generation of P. lepida, mortality was highest during the cocoon stage when bird predation was estimated to be most intense (Nishida et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Differential performance of contrasting defensive traits of cocoons of two moth species against bird predation

Furukawa

Nakanishi

Honma

et al. 2021

Entomological Science

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Prey defensive traits against predators can be categorized into primary defense (avoiding detection) and secondary defense (avoiding attack after detection). There are trade-offs between these two defensive traits, which consider the cost of defense. To quantify the predation avoidance efficacy of both defensive traits against common predators, we compared bird predation pressures and the corresponding avoidance measures of cocoons of two nettle moth species, which utilize contrasting avoidance strategies: Parasa lepida (investing predominantly in primary defense) and Monema flavescens (investing predominantly in secondary defense). Field censuses revealed that bird predation was the most significant mortality factor for both species. The survival rate of cocoons was significantly higher for M. flavescens than for P. lepida, although M. flavescens were more conspicuous than P. lepida. Measurement of prepupae (cocoon content) mass, and experiments on the feeding preferences of the prepupae of both species using chicks, confirmed a similar quantity and quality of both speciesʼ prepupae as prey items. Our results were explained by the advantage of cocoon hardness outweighing the disadvantage of cocoon conspicuousness. The predation behavior of wild birds suggested that they spent considerably longer handling than searching for cocoons, which accounted for their cocoon preference for P. lepida over M. flavescens in the context of optimal foraging theory. Our results suggested that secondary defense was more effective in reducing bird predation than primary defense in limacodid cocoons.

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Studies on the cocoon of the oriental moth, Monema (Cnidocampa) flavescens, (lepidoptera:limacodidae). III. Structure and composition of the cocoon in relation to hardness.

Cited by 8 publications

References 2 publications

Cocoonase is indispensable for Lepidoptera insects breaking the sealed cocoon

Cocoonase is indispensable for Lepidoptera insects breaking the sealed cocoon

Identification and classification of silks using infrared spectroscopy

Differential performance of contrasting defensive traits of cocoons of two moth species against bird predation

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