Silk Spinning Research Articles

Individual trail marking by larvae of the scarce swallowtail Iphiclides podalirius L. (Lepidoptera; Papilionidae).

Starting from permanent resting sites covered with silk, the solitary and territorial larvae of I. podalirius spin silk trails leading to feeding sites. It is shown that the silk contains a volatile trail marker. The larvae recognize their own trails and prefer them to those laid by conspecific caterpillars. Trail marking appears to be widespread among larvae of Lepidoptera.

Fine structure and function of the prosomal glands of the two-spotted spider mite, Tetranychus urticae (Acari, Tetranychidae)

The prosomal glands of Tetranychus urticae (Acari, Tetranychidae) were examined light and electron microscopically. Five paired and one unpaired gland are found both in females and males. The silk spinning apparatus consists of paired silk glands which extend laterally on both sides of he esophagus into the pedipalps. There, they enter the terminal silk gland bag which opens into a silk bristle at the apex of hte pedipalps. The salivary secretions are formed in three paired glands which have an interconnecting duct, the podocephalic canal. The dorsal podocephalic glands may produce a serous secretion, the anterior podocephalic glands a mucous secretion, and the coxal organ may add a liquid, ion-rich secretion. These secretions pass the podocephalic canal and reach the mouth at the apex of the gnathosome. The function of the paired tracheal organs and the unpaired tracheal gland is still unclear. The tracheal gland may produce a secretion which facilitates the movement of the fused chelicerae and the stylets.

Communal silk-spinning by larvae ofDendromyrmex tree-ants (Hymenoptera: Formicidae)

Dendromyrmex chartifex andD. fabricii are weaver ants: the mature larvae of these formicine species add silk to the arboreal carton nests. This material strengthens the layers of vegetable fibers, which form the bulk of the nests and are contributed by the workers. The communal silk spinning is the most primitive yet discovered and may represent the first stage in the evolution of weaving. The larvae, rather than the workers that hold them in their mandibles, make the lateral weaving movements, and their behavior differs from conventional cocoon spinning only in the orientation of the movements relative to the body. Moreover, larvae often contribute silk in this manner even when unattended by workers. Both male and worker-destined larvae spin communally; whether they contribute equal quantities per capita remains to be determined.

Ultrastructure of the striated ventromental plates and associated structures of larval Chironominae (Diptera: Chironomidae) and their rôle in silk‐spinning

The ultrastructure of striated ventromental plates and their relationship to other parts of the larval head capsule have been studied in two Chironominae species, Microtendipes pedellus (Degeer) and Chironomus riparius Meigen, by scanning electron microscopy and light microscopy, including observation of thin sections. In both species the inner surface of the striated plates has a complex microarchitecture and is closely associated with a cuticular structure termed the maxillary plate. It is suggested that the striated and associated maxillary plates play an important rr̂le in the process by which larvae of the Chironominae spin silk.

The spinning of silk, 1. Molecular weight, subunit structure, and molecular shape of bombyx mori fibroin

AbstractThe molecular structure of Bombyx mori fibroin is still subjected to much controversy; there are discordant reports in the literature on both the value of the molecular weight and the subunit structure of the molecule. The method reported in the present paper allows the molecular weight of Na2CO3 extracted fibroin samples to be unambiguously determined, and investigations on the composition and the molecular weight of the peptides arising from the degradation process succeeded in establishing some overall aspects of the structure of the subunits. The main results are: (1) the molecular weight of undegraded fibrion is 4 · 105; (2) two small subunits are disulfide linked to the main chain; (3) the subunits are located near the terminals of the main chain; (4) in agreement with previous partial literature data, the small subunits are rich in bulky and acid amino acids; our work further shows that they possess a three‐block structure, consisting of a central hydrophobic core bearing two strongly acid sequences at the terminals. The mechanism of degradation of the fiber appears to be directed by structural, rather than chemical, factors, and its detailed investigation may represent a valuable method to determine the molecular architecture of the fiber.

Daily changes in the sensitivity of wax‐moth larvae, Galleria mellonella, to cooling stress

ABSTRACT. Sensitivity to cooling stress in the last instar larvae of Galleria mellonella was measured as (a) the number of extra larval moults, (b) the number of larvae retaining the ability to secrete silk, and (c) the number showing arrested development. With respect to (a) and (b) there were considerable differences in sensitivity across the day. A relationship was observed between the number of additional larval moults induced by chilling and the ability of prepupal larvae to spin silk: the periods during the 24 h when the most larvae passed through additional larval moults were periods characterized by the smallest number of larvae capable of spinning, and vice versa. These daily changes were apparently partly independent of developmental age. Daily variations in sensitivity also occurred when larvae of the same age were cooled at different times of day. It is suggested that these rhythms in cold‐sensitivity are related to a cold‐sensitive rhythm in juvenile hormone secretion, or hormone sensitivity in the tissues.

Silk Spinning as an Escape Mechanism in Hydropsyche orris Larvae following Removal from Water (Trichoptera: Hydropsychidae)

When submerged tree limbs, with nets and retreats of Hydropsyche orris Ross, were removed from the water and began to dry, the larvae attached silk to the limb surface and lowered themselves by spinning additional silk. This escape mechanism would be important for survival in the event of subsiding water levels.

Bionomics of Nearctic Bee-Associated Meloidae (Coleoptera). A Comparative Analysis of Larval Host-Seeking Behavior among the Meloinae and Nemognathinae1,2,3

The effect of light and temperature on the host-seeking (prefeeding) behavior of bee-associated first-stage meloid larvae (Meloinae and Nemognathinae) was investigated in the laboratory. The triungulins of both groups were photo- and thermotactic. Also, they could both survive up to 30 days, depending on the availability of suitable food and/or moisture. A definite behavioral response to static electrical charges was demonstrated by the larvae. Silk spinning by the Nemognathinae was studied and an attempt made to determine the significance of silk production.

Studies of acetylcholinesterase of the central nervous system of Galleria mellonella

The central nervous system (CNS) of Galleria mellonella contains an active acetylcholinesterase, whose level changes during the development of the central nervous system. The enzyme occurs in five forms of different electrophoretic mobilities and the relative amounts of each form varies with the life state of Galleria. The molecular weight of the enzyme was estimated to be approximately 280,000 ± 15,000. It appeared to consist of four polypeptide subunits. Injection of the anticholinesterase, eserine, into the last larval stage inhibits the silk spinning and delays the formation of pupa by more than 2 weeks when compared with the controls.

岡谷における製糸工場の分布とその立地の変遷について

岡谷における製糸工場の分布とその立地の変遷について

Wear resistance of the pair: Spinning ring-traveler

1. It is uneconomical to use carbonitrided steels 45G2, 30KhGSA, 40Kh, ShKh15 and 38KhMYuA as replacements for carbonitrided steel 40 for spinning rings because their resistance is low. 2. Rings made of carbonitrided steel 4Kh13, quenched and low tempered last 1.5–2 times longer on wool and 4.8 times longer on silk spinning machines compared with similar rings of steel 40. 3. Steels 4Kh13, 2Kh13 and 1Kh13 were included in the proposed State Standard Specification “Ring-Spinning and Splicing Machines”. 4. Carbonitrided steels 4Kh13, 2Kh13 and 1Kh13 are recommended for heavily loaded parts operating under high specific pressures.

Étude quantitative de l'acide ribonucléique dans les glandes séricigènes chez Bombyx Mori L

Étude quantitative de l'acide ribonucléique dans les glandes séricigènes chez Bombyx Mori L

Geographical Factors concerning the Supply Regions of the Factory Girls in Niigata Prefecture (2)

This is the second report of the supply regions of factory girls, “dekasegi-zyoko”, in Niigata prefecture. The first one-was published on “The Geography (1940)”. The reason why women emigrate to other prefectures is concluded as follows : 1) The scareceness of agricultural productions compared to the population density. 2) Villages and towns which supply girls, are near in location to Nagano and Gunma prefectures which demand silk spinning workers. 3) More profit can be get from silk factory than other occupation in their home villages. 4) The policy of demand regions to hire, and the local custom off supply regions.

Geographical Factors concerning the Supply Regions of the Factory Girles in Niigata Prefecture

This is the second report of the supply regions of factory girls, “dekasegi-zyoko”, in Niigata prefecture. The first one-was published on “The Geography (1940)”. The reason why women emigrate to other prefectures is concluded as follows : 1) The scareceness of agricultural productions compared to the population density. 2) Villages and towns which supply girls, are near in location to Nagano and Gunma prefectures which demand silk spinning workers. 3) More profit can be get from silk factory than other occupation in their home villages. 4) The policy of demand regions to hire, and the local custom off supply regions.

Associated Learned Societies of Liverpool

THE triennial public exhibition and soirée organized by the Associated Learned Societies of Liverpool and District to illustrate the progress in science and education since their last exhibition in 1935 was held in the City Technical College on October 22. During the course of the exhibition, Prof. E. W. Marchant gave a lecture on “Television”, H. Ken-drick on “Changing India”, W. H. Watts on “The Moon”, D. Caradog Jones on “The Changing Population of Merseyside”, Prof. J. T. Craig on “Veterinary Pathology”, and a number of shorter talks were given in the individual rooms. The Institute of Chemistry and the Society of Chemical Industry exhibited process demonstrations of artificial silk spinning, products obtainable from cotton seed, demonstrations of the action of dirt particles under the influence of electrical forces, dyeing and armour-plate glass ; the British Association of Chemists exhibited a combined temperature and humidity recorder, smoke density determination apparatus and samples from the plastics industry. The Liverpool Biological Society's room included a demonstration exhibit by Prof. J. H. Orton on his Dee fisheries work, Dr. R. J. Daniel on pearl-formation, and Mrs. Bisbee on the ductless glands. Mr. Eric Hardy had arranged a special “Country-Side” Room with Nature films, photographs, habitat groups of British birds and mammals, bird migration ('ringing') and flight (bird-wing) displays, illuminated natural colour lantern slides, bird sanctuary devices and maps of local bird distribution. The exhibition also included natural colour films, an ingenious micro -projector by Mr. A. V. Wilkinson, Dr. Glynn Morris's geological collection, and in the Engineering Society's room, a trafficator for cyclists invented by Mr. A. Robins.