Colony composition and some costs and benefits of facultatively communal behavior in a Trinidadian webspinner, Clothoda urichi (Embiidina: Clothodidae

ABSTRACT Clothoda urichi (Saussure), a Trinidadian webspinner, is facultatively communal; its colonies vary from solitary individuals to groups of reproductive females with their offspring sharing a silk covering. Communal females produce significantly more eggs than solitary females, but this increase is countered by significantly higher egg parasitism rates experienced by females reproducing under crowded conditions. C. urichi establishes colonies by remaining in its natal silk galleries, or by dispersing to establish a new gallery or to join an existing one. A model, developed by logistic regression analysis and based on the estimated area covered by silk, can be used to predict if a colony is solitary or communal, or whether half-grown nymphs are present

Structural characterization of nanofiber silk produced by embiopterans (webspinners)

Embiopterans produce silken galleries and sheets using exceptionally fine silk fibers in which they live and breed. In this study, we use electron microscopy (EM), Fourier-transform infrared (FT-IR) spectroscopy, wide angle X-ray diffraction (WAXD) and solid-state nuclear magnetic resonance (ssNMR) techniques to elucidate the molecular level protein structure of webspinner (embiid) silks. Silks from two species Antipaluria urichi and Aposthonia ceylonica are studied in this work. Electron microscopy images show that the fibers are about 90–100 nm in diameter, making webspinner silks among the finest of all known animal silks. Structural studies reveal that the silk protein core is dominated by β-sheet structures, and that the protein core is coated with a hydrophobic alkane-rich surface coating. FTIR spectra of native embiid silk shows characteristic alkane CH2 stretchings near 2800–2900 cm−1, which decrease approximately 50% after washing the silk with 2 : 1 CHCl3 : MeOH. Furthermore, 13C ssNMR data shows a significant CH2 resonance that is strongly affected by the presence of water, supporting the idea that the silk fibers are coated with a hydrocarbon-rich layer. Such a layer is likely used to protect the colonies from rain. FTIR data also suggests that embiid silks are dominated by β-sheet secondary structures similar to spider and silkworm silk fibers. NMR data confirms the presence of β-sheet nanostructures dominated by serine-rich repetitive regions. A deconvolution of the serine Cβ NMR resonance reveals that approximately 70% of all seryl residues exist in a β-sheet structure. This is consistent with WAXD results that suggest webspinner silks are 70% crystalline, which is the highest crystalline fraction reported for any animal silks. The work presented here provides a molecular level structural picture of silk fibers produced by webspinners

A New Braconid Genus (Hymenoptera) Parasitizing Webspinners (Embiidina) in Trinidad

Volume: 92Start Page: 505End Page: 51

Silk Spinning Behavior Varies from Species-Specific to Individualistic in Embioptera: Do Environmental Correlates Account for this Diversity?

Edgerly, Janice S., Sandel, Brody, Regoli, Isabel, Okolo, Onyekachi (2020): Silk Spinning Behavior Varies from Species-Specific to Individualistic in Embioptera: Do Environmental Correlates Account for this Diversity? Insect Systematics and Diversity 4 (2), No. 2: 1-14, DOI: 10.1093/isd/ixaa00

Exploration of substrate vibrations as communication signals in a webspinner from Ecuador (Embioptera: Clothodidae)

Embiopterans are among the least known of all insect orders, and yet their behavior is worthy of investigation for many reasons. They spin silk produced in glands in their front tarsi and live in groups, usually mothers with their young and sometimes in large colonies with many reproductive females sharing the silk. We discovered a large embiid (Clothodidae) in an Ecuadorian rain forest living under camouflaged silk sheets spun onto the bark of trees. Observations in previous studies of a related Trinidadian clothodid revealed that individuals shake and lunge their bodies in response to intruders of their silk domicile. We took the opportunity afforded by the discovery of the large clothodids to rear them in the laboratory and to investigate their communication behavior. We used piezoelectric film to detect substrate vibrations generated by adult females as elicited by a variety of intruders (an artificial stimulus, conspecific female or male, or a female of different species of webspinners). The residents produced three signals distinguishable by behavioral action, frequency (hertz), pulses per bout, and amplitude at peak frequency. We designated these as lift silk, shake, and snapback. Shakes varied the most in amplitude and frequency in response to the different intruders, and therefore, we propose that shakes may transmit the most information as individuals contact each other. This is the first report to characterize spectral qualities and contexts of substrate vibrations in an embiopteran