Life Beneath Silk Walls: A Review of the Primitively Social Embiidina

I review and summarize the scattered information on embiids (Order Embiidina), with an emphasis on details of colony structure and maternal care. I summarize experimental and observational field results from a detailed study on parental and communal behavior of Antipaluria urichi, a Trinidadian webspinner. Topics discussed include the function of maternal behavior, interactions with egg parasitoids, antipredator attributes of communal living, and possible functions of silk. I also compare features of webspinner sociality to other communal insects and spiders. In addition, I discuss promising topics for future study, including male dimorphism, the possibility of higher sociality, and communication systems

Choreography of silk spinning by webspinners (Insecta: Embioptera) reflects lifestyle and hints at phylogeny

Silk spinning defines the morphologically constrained embiopterans. All individuals spin for protection, including immatures, adult males and the wingless females. Enlarged front tarsi are packed with silk glands and clothed with ejectors. They spin by stepping with their front feet and releasing silk against substrates and onto preexisting silk, often cloth-like. Spinning is stereotypical and appears to differ between species in frequency and probability of transition between two spin-step positions. This spinning choreography was assessed using thousands of spin-steps scored in the laboratory for 22 species to test: (1) the body size hypothesis predicting that spinning would be more complex for larger species; and (2) the phylogeny hypothesis which predicted that spinning would display phylogenetic signal. Tests relied on published phylogenies for the order Embioptera. Independent contrast analysis revealed relationships between five spin characteristics and body size, whereby, for example, larger webspinners invested in relatively larger prothoracic tarsi used for spinning and in spin-steps that would yield expansive silk coverings. Spin-step dynamics displayed a phylogenetic signal for the frequency of six spin-steps and for 16 spin-step transitions. Discussion focuses on patterns revealed by analysis of phylogenetic signal and the relationship to life style and to recently discovered chemical characteristics of silk

International Space Station (ISS) Potable Water Dispenser (PWD) Beverage Adapter (BA) Redesign

The Potable Water Dispenser used on the International Space Station (ISS) interfaces with food and drink packages using the Beverage Adapter and Needle. Unexpected leakage has been seen in this interface. The Beverage Adapter used on-orbit was returned to the ground for Test, Teardown, and Evaluation. The results of that investigation prompted a redesign of the Beverage Adapter and Needle. The Beverage Adapter materials will be changed to be more corrosion resistant, and the Needle will be redesigned to preclude leakage. The redesigns have been tested and proven

Lichens, Sun, and Fire: A Search for an Embiid-Environment Connection in Australia (Order Embiidina: Australembiidae and Notoligotomidae)

This investigation is the first to quantify the degree of habitat specialization for any species within the little-known order Embiidina. The lichen and plant communities found in the habitats of two sympatric species, one living on lichens encrusted on granite and another feeding in leaf litter, were characterized using a process of ordination and cluster analysis. Differences among 40 samples and their relationships to environmental factors were probed statistically using Spearman’s coefficient of rank correlations generated by comparing rank similarity matrices of the census sites. The lichen eater, Notoligotoma hardyi (Friederichs), was more abundant in areas with strong southern exposures and was associated with higher lichen abundance. They preferentially grazed on particular lichens, the first indication that an embiid shows specialization in feeding. The detritivore, Australembia incompta Ross, was closely associated with particular plant communities, especially those less susceptible to fire. Their colonies were more common in rockier, coastal areas and less abundant in grasslands and habitats dominated by Eucalyptus. Insight into ecological variation within the order can guide further exploration of other traits (such as silk structure and function and primitive social behavior) in this rarely studied group of insects

Course-based campus environmental research projects

Campus administrators and faculty across the country are realizing the educational and economic value of campus greening. Many administrators have established clear environmental campus policies in an effort to recognize the economic value of green institutional operations and to respond to the need for adopting sustainable practices. Faculty and students have contributed to the green movement by integrating the physical campus into the educational process. At many institutions, students have led efforts to implement environmentally friendly, and in some cases, economically sensible practices particularly in the areas of energy conservation and waste management. Faculty and students have worked together on class projects and independent research to contribute to the greening movement. Many institutions have a legacy of environmental consciousness that began in the early 1970s. At Santa Clara University (SCU), in Santa Clara, California, greening has occurred more recently with the start of an Environmental Studies program in 1992 and a Campus Environmental Assessment in 1995. A strong driving force for greening of the campus has been student and faculty interest manifested primarily as course­based campus projects. This article discusses some outcomes of environmental research conducted by students and faculty in chemistry, biology and anthropology. Some avenues are suggested for enhancing the research experience and for incorporating significant findings into the University\u27s modus operandus

A new braconid genus (Hymenoptera) parasitizing webspinners (Embiidina) in Trinidad

Early in 1984, while conducting field studies on embiid behavior in the Arima valley of northern Trinidad, the junior author ob- served a braconid wasp ovipositing into the silk webs of an embiid, Clothoda urichi (Saussure) [Clothodidae]. The wasp and a paralyzed embiid were collected, and another wasp was successfully reared from that host. Specimens were sent to the senior author, then stationed at the National Museum of Natural History (USNM), who determined it to be a new braconid genus. A search of the USNM collection yielded no comparable specimens; however, during a subsequent search of the Museum of Comparative Zoology (MCZ) collection a specimen of a different, but related, species was found. Shenefelt (1980) provided a comprehensive index to recorded braconid hosts, which does not include any Embiidina. Callan (1952) mentioned that he collected numerous white cocoons from embiid webs in Trinidad, and he reared a braconid from these which was identified only as Apanteles sp. He suggested that these were parasites of lepidopterous larvae that sometimes live under the silk, not parasites of the webspinners. The establishment of this new genus as a parasite of webspinners therefore provides a totally new host order record for the family Braconidae

Relating the Cost of Spinning Silk to the Tendency to Share It for Three Embiids with Different Lifestyles (Order Embiidina: Clothodidae, Notoligotomidae, and Australembiidae)

Although adult female embiids (Order Embiidina) superficially lack morphological diversity, their variety of habitats may impose distinct selective pressures on behavior, such as their use of silk and their tendency to aggregate. For example, where silk serves as a primary defense from environmental threats, coloniality might be adaptive. The cost of production or spinning might also prompt them to share silk. These ideas were tested in laboratory trials involving three species of embiids with different lifestyles: an arboreal species (Antipaluria urichi (Saussure) from a neotropical rain forest, a species (Notoligotoma hardyi (Frederichs) that dwells on surfaces of granite outcrops in Australia, and another Australian species (Australembia incompta Ross) that stitches leaf litter together. The cost of spinning silk was analyzed by recording CO2 output in the short term during spinning and by measuring performance in long-term trials where embiids were forced to repeatedly replace their silk. Their subsequent development or reproductive output was scored. Overall, the cost of spinning was relatively low. However, the tendencies to spin and to aggregate varied in a manner related to how silk is used in the field. As such, the more exposed the embiid is to the elements, as for the two species that spin on surfaces, the more silk they spun and the more likely they settled near a neighbor. In contrast, the embiid that used dead leaves (not silk) as walls for their abodes produced scant silk and showed little tendency to aggregate

On new characters of the eggs of Embioptera with the description of a new species of Saussurembia (Anisembiidae)

Nine egg characters for eleven species of Embioptera are described for the first time. Egg variability indicates its potential use in taxonomy. Here, we analyse the correlation of this variability with the ordinal classification. In addition, a new species of Saussurembia (Anisembiidae) from Trinidad is described, including classical traits in the systematics of Embioptera (adult male and female), as well as general features of the egg and maternal behaviour

The phylogeny and classification of Embioptera (Insecta)

A phylogenetic analysis of the order Embioptera is presented with a revised classification based on results of the analysis. Eighty-two species of Embioptera are included from all families except Paedembiidae Ross and Embonychidae Navás. Monophyly of each of the eight remaining currently recognized families is tested except Andesembiidae Ross, for which only a single species was included. Nine outgroup taxa are included from Blattaria, Grylloblattaria, Mantodea, Mantophasmatodea, Orthoptera, Phasmida and Plecoptera. Ninety-six morphological characters were analysed along with DNA sequence data from the five genes 16S rRNA, 18S rRNA, 28S rRNA, cytochrome c oxidase I and histone III. Data were analysed in combined analyses of all data using parsimony and Bayesian optimality criteria, and combined molecular data were analysed using maximum likelihood. Several major conclusions about Embioptera relationships and classification are based on interpretation of these analyses. Of eight families for which monophyly was tested, four were found to be monophyletic under each optimality criterion: Clothodidae Davis, Anisembiidae Davis, Oligotomidae Enderlein and Teratembiidae Krauss. Australembiidae Ross was not recovered as monophyletic in the likelihood analysis in which one Australembia Ross species was recovered in a position distant from other australembiids. This analysis included only molecular data and the topology was not strongly supported. Given this, and because parsimony and the Bayesian analyses recovered a strongly supported clade including all Australembiidae, we regard this family also as monophyletic. Three other families – Notoligotomidae Davis, Archembiidae Ross and Embiidae Burmeister, as historically delimited – were not found to be monophyletic under any optimality criterion. Notoligotomidae is restricted here to include only the genus Notoligotoma Davis with a new family, Ptilocerembiidae Miller and Edgerly, new family, erected to include the genus Ptilocerembia Friederichs. Archembiidae is restricted here to include only the genera Archembia Ross and Calamoclostes Enderlein. The family group name Scelembiidae Ross is resurrected from synonymy with Archembiidae (new status) to include all other genera recently placed in Archembiidae. Embiidae is not demonstrably monophyletic with species currently placed in the family resolved in three separate clades under each optimality criterion. Because taxon sampling is not extensive within this family in this analysis, no changes are made to Embiidae classification. Relationships between families delimited herein are not strongly supported under any optimality criterion with a few exceptions. Either Clothodidae Davis (parsimony) or Australembiidae Ross (Bayesian) is the sister to the remaining Embioptera taxa. The Bayesian analysis includes Australembiidae as the sister to all other Embioptera except Clothididae, suggesting that each of these taxa is a relatively plesiomorphic representatative of the order. Oligotomidae and Teratembiidae are sister groups, and Archembiidae (sensu novum), Ptilocerembiidae, Andesembiidae and Anisembiidae form a monophyletic group under each optimality criterion. Each family is discussed in reference to this analysis, diagnostic combinations and taxon compositions are provided, and a key to families of Embioptera is included

Structural and wetting properties of nature\u27s finest silks (order Embioptera)

Insects from the order Embioptera (webspinners) spin silk fibres which are less than 200 nm in diameter. In this work, we characterized and compared the diameters of single silk fibres from nine species—Antipaluria urichi, Pararhagadochir trinitatis, Saussurembia calypso, Diradius vandykei, Aposthonia ceylonica, Haploembia solieri, H. tarsalis, Oligotoma nigra and O. saundersii. Silk from seven of these species have not been previously quantified. Our studies cover five of the 10 named taxonomic families and represent about one third of the known taxonomic family-level diversity in the order Embioptera. Naturally spun silk varied in diameter from 43.6 ± 1.7 nm for D. vandykei to 122.4 ± 3.2 nm for An. urichi. Mean fibre diameter did not correlate with adult female body length. Fibre diameter is more similar in closely related species than in more distantly related species. Field observations indicated that silk appears shiny and smooth when exposed to rainwater. We therefore measured contact angles to learn more about interactions between silk and water. Higher contact angles were measured for silks with wider fibre diameter and higher quantity of hydrophobic amino acids. High static contact angles (ranging up to 122° ± 3° for An. urichi) indicated that silken sheets spun by four arboreal, webspinner species were hydrophobic. A second contact angle measurement made on a previously wetted patch of silk resulted in a lower contact angle (average difference was greater than 27°) for all four species. Our studies suggest that silk fibres which had been previously exposed to water exhibited irreversible changes in hydrophobicity and water adhesion properties. Our results are in alignment with the ‘super-pinning’ site hypothesis by Yarger and co-workers to describe the hydrophobic, yet water adhesive, properties exhibited by webspinner silk fibres. The physical and chemical insights gained here may inform the synthesis and development of smaller diameter silk fibres with unique water adhesion properties