The Effect of Feeding History on Prey Capture Behaviour in the Orbweb Spider Argiope keyserlingi Karsch (Araneae: Araneidae)

The prey capture behaviour of the orb-web spider Argiope keyserlingi Karsch was examined experimentally by subjecting spiders to two different feeding regimes (food deprived and food satiated) and three types of prey: Drosophila, blowflies (Lucilia cuprina) and bees (Apis mellifera). The attack behaviour of the spiders was influenced by both their foraging history and the type of prey. Food deprived spiders attacked Drosophila and bees more frequently than food satiated spiders, and food satiated spiders travelled more slowly to any of the prey types than food deprived spiders. Furthermore, Drosophila were never wrapped in silk but only grasped with the chelicerae, whereas both blowflies and bees were always wrapped. This provides experimental confirmation that feeding history affects the decision of orb-web spiders to accept or reject any given prey.     

Cooperation and Prey Capture Efficiency in a Social Spider,Anelosimus eximius (Araneae,Theridiidae)

We studied the efficiency of the hunt and the characteristics of cooperation during the prey capture in a social spider Anelosimus eximius. Two natural types of prey of roughly the same length (20 mm) were used: grasshoppers (Orthoptera) and moths (Lepidoptera); 128 tests were made on 14 colonies, the smallest with 20 and the largest with 1,700 individuals. Test times were 12.00 h, defined as an inactive period for the spiders and 18.00 h, defined as an active period. Overall capture rate of intercepted prey was 66%: it was higher in large colonies or at 18.00 h, when more spider alerts were triggered by the struggling prey. Characteristics of cooperation during capture did not vary with colony size. Capture rate was higher for grasshoppers than moths (73%-58%) in spite of similar number of alerts (76%-87%); so moths must have been more difficult to capture. For both prey types, large colonies capture more rapidly and so had advantages in terms of time gain. We showed that cooperation depended on prey type: more spiders mobilised to attack moths and attack was faster than on grasshoppers. This may be interpreted as an adaptive response of the group to the prey type.     

The Spider Genera Singa and Hypsosinga (Araneae, Araneidae) in Israel

Israeli spiders of the orb-weaver genera Singa and Hypsosinga (Araneidae) have been revised. New and updated information on the little known Mediterranean spider fauna, pertaining to European species as well, is presented. Some of the species have never been adequately described or illustrated. All the species previously described from the Middle East and adjacent countries were re-examined. Aranea neta is newly placed in Singa and the following new synonyms are defined: Lithyphantes sepfemguffafus Simon, 1873, along with Araneus decorus (Simon, 1891) and Lithyphantes pollocki Denis, 1956 = Singa neta (O. P.-Cambridge, 1872); Singa afjinis O. P.-Cambridge, 1876 along with Singa attica Simon, 1884 = Hypsosinga albovittata (Westring, 1851). The presence of three species formerly reported from Israel, including one erroneously determined, has been confirmed, and the occurrence of another three species previously unknown from this country has been proved. All are newly described. Keys, detailed illustrations of diagnostic characters and records of -distribution are provided for each species.     

Prey Capture Behaviour in the Social Spider Anelosimus eximius (Araneae: Theridiidae): Responses to Prey Size and Type

Some species of web building spiders use different capture tactics for different prey types. The main factors influencing the attack behaviour are the ability of the insect to escape, the risks of injury to the spiders and prey size. This study evaluated the effects of size and prey type on prey capture behaviour of the social spider Anelosimus eximius as influenced by the number of spiders attracted by prey movements that did not bite until the immobilization (bystanders) and the number of spiders that contributed to prey immobilization (catchers). We carried out a two‐factor (prey size and type) experiment offering prey belonging to four orders: Diptera, Lepidoptera, Hymenoptera and Orthoptera, in a size gradient within each prey type. Both factors influenced the number of spiders recruited as bystanders, but only prey body size influenced the number of catchers in the subduing process. The possible advantages of the presence of bystanders around the interception site are discussed.     

Testing the Functions of Detritus Stabilimenta in Webs of Cyclosa fililineata and Cyclosa morretes (Araneae: Araneidae): Do They Attract Prey or Reduce the Risk of Predation?

Spiders of the genus Cyclosa often add prey remains and other debris to their orb‐webs. The function of silk decorations is generally associated with defense against predators or with the attraction of prey, but few studies have focused on stabilimenta containing detritus. In this study, we used artificial webs with and without the detritus stabilimenta of two species of Cyclosa to investigate whether these structures increase the number of insects intercepted. Artificial models of spiders and stabilimenta were used to compare the frequency of attacks against different shapes. We also conducted choice experiments in laboratory to determine whether detritus columns attracted Drosophila melanogaster (Diptera: Drosophilidae) and Trigona angustula (Hymenoptera: Apidae, Meliponinae) to the webs. The frequency of interception in artificial webs with a stabilimentum was similar to that of webs without such structure. The taxonomic composition and biomass of insects were also similar in both types of artificial webs. The choice experiments showed no significant tendency in attraction to webs with a stabilimentum. However, models of spiders were attacked at a higher frequency than those simulating detritus columns and silk decorations. These findings argue against the prey attraction hypothesis and suggest that the addition of stabilimenta to webs of Cyclosa could reduce the intensity of predation, possibly by disrupting the image of the spider's outline.     

Araneus rotundicornis Yaginuma (1972) (Araneae: Araneidae) new to Korean Spider Fauna

Araneus rotundicornis, which has been known as a species endemic to Japan, was caught in Mt. Weolaksan in Chungcheongbuk-do, Korea. And it is described and illustrated in this report.     

Male Performance and Body Size Affect Female Re-Mating Occurrence in the Orb-Web Spider Leucauge mariana (Araneae, Tetragnathidae)

Females can affect male probabilities of paternity success through behavioural, morphological and/or physiological processes occurring during or after copulation. These processes under female-control include the acceptance or rejection of mating attempts by subsequent males. Leucauge mariana is an orb weaving spider that shows male mate guarding of penultimate females, male–male competition on female webs and copulatory plugs, suggesting a polyandric mating system. The aim of the present study was to ascertain whether male behaviour during courtship and copulation in L. mariana relate with female re-mating decisions. Forty-three virgin females were exposed to up to three males until they mated. In 24 cases, the copulatory plug was absent after mating and females were exposed the next day to up to three other males. Eighteen females accepted a second mating. Relatively larger females were more receptive to second matings and were more likely to copulate if the second male was smaller. Longer duration of female tapping and abdominal bobbing during courtship, and first copulations with less short insertions and more flubs, were associated with increased female acceptance to second matings. The results indicate cryptic female choice on male courtship and copulatory performance and suggest female-control over the determination of male mating success in this spider species.     

Determinants of Mating Frequency in the Spiny Orbweaving Spider,Micrathena gracilis (Araneae: Araneidae)

Male Micrathena gracilis require two copulations, separated by a dismount, in order to inseminate both reproductive tracts of the female. We examined several factors that might influence a male's copulatory success. Web structure influenced male courtship and dismount tactics, but not copulatory frequency. The presence of another male reduced the likelihood of a given male copulating with both tracts, a limitation mediated by sexual responsiveness of the female. Mating status of the female did influence copulatory frequency; males were less likely to copulate a second time with nonvirgin females. In summary, males modify mating activities to reduce predation by females, to reduce intermale competition, and to avoid expending gametes when there is little chance of fertilization. Females influence males by predatory activities, mediated through web structure, and enhancing sperm competition among males.     

Stabilimenta of Philoponella vicina (Araneae: Uloboridae) and Gasteracantha cancriformis (Araneae: Araneidae): Evidence Against a Prey Attractant Function

Both the uloborid Philoponella vicina and the araneid Gasteracantha cancriformis spiders sometimes placed silk stabilimenta on non-orb "resting webs" that consisted of only one or a few lines. These webs completely lacked sticky silk, so their stabilimenta could not function to attract prey. Some non-orbs were built by spiders when their orb webs are damaged. These observations contradict the prey attraction camouflage hypothesis for stabilimentum function, but are compatible with the spider camouflage and web advertisement to avoid web destruction hypotheses.     

Prey Capture and Feeding in the Social Spider Anelosimus eximius

Wild colonies of the social spider Anelosimus eximius (Araneae, Theridiidae) appear often to be food-limited and not all females come to reproduction. Using a limited number of marked females in an artificial colony, set up in the laboratory, this study attempts a first analysis of the participation in prey capture and ingestion. Marked females of the same age and experience were observed during the attack of prey insects, the ensuing transportation of the prey to the retreat, and the feeding session. No correlation was found between the time females spent hunting and the time they spent feeding. Females that laid eggs had fed longer and imbibed more nutrients, but had not hunted more than those females that did not reproduce. These, it is speculated, were denied access to the prey by the reproducing females.     

Untersuchungen zur Taxonomie der Gattung Araniella (Araneae, Araneidae)

Morphological and ethological criteria were used in studying the taxonomic relations between different forms within the genus Araniella . Criteria for a diagnosis of all species and subspecies of the genus are given. A. opisthographa (Kulczyski, 1905), A. cucurbitina (Clerck, 1757), A. proxima (Kulczyski, 1885) and A. maderiana (Kulczyski, 1905) form one group of sibling species in the narrowest sense, A. alpica (L. Koch, 1869) and A. inconspicua (Simon, 1874) a second distinct one. A. displicata (Hentz, 1847) seems to occupy a relatively isolated position. A. cossoni (Simon, 1885) is regarded as a synonym for A. cucurbitina . It is impossible to make a statement about the status of A. silesiaca (Fickert, 1876) and A. croatica (Kulczyski, 1905) because of the lack of sufficient material. A. silesiaca is not a synonym for Araneus crispulus Tullgren, 1952, a species which does not belong to the genus Araniella .     

中国云南高黎贡山园蛛属4新种记述(蜘蛛目:园蛛科)

本文记述了采自中国云南高黎贡山的园蛛属Amneus 4新种:春林园蛛,新种Amneus chunlin sp.nov.,李氏园蛛,新种Araneusliae sp.nov.,丰盛园蛛,新种Amneua plenus sp.nov.和亚坪园蛛,新种Araneus yapingensis sp.nov..模式标本正模及部分副模保存于湖南师范大学(HNU),部分副模将保存于美国加州科学学院(CaAS).文中量度单位为mm.     

Elektronenmikroskopische untersuchungen an den Guanin-Speicherzellen von Araneus diadematus clerck (Araneae,Araneidae)

Zusammenfassung Bei einigen Spinnen, vor allem aus der Familie der Araneidae, bilden funktionell umgewandelte Mitteldarmzellen unmittelbar unter der Hypodermic eine nahezu geschlossene Zellschicht, die mehr oder minder stark mit Guaninkristallen angefiillt sein kann.Die distalen Zellbereiche dieser von uns als Guanocyten bezeichneten Zellen verzahnen rich mit der Hypodermis selbst oder stehen mit dem schmalen hypodermalen Hämolymphsinus in Verbindung. Thre proximalen Enden sind lang ausgezogen und schieben sich zwischen nicht umgewandelte Resorptionszellen. Jede Guanocyte steht mit dem Mitteldarmlumen in direkter Verbindung.Auf Grund des Organellenbestandes sind die Guanocyten als spezialisierte Mitteldarmzellen auzusprechen, die während der reproduktiven Periode die übrigen exkretorisch tätigen Gewebe bzw. Organe unterstützen oder ergänzen, indem sie der Hämolymphe, der Hypodermis und den benachbarten Resorptionszellen pinocytotisch purinhaltige Abbauprodukte und andere Exkrete entnehmen. Dieselben werden unter Mitwirkung eines glatten endoplasmatischen Retikulums umgebaut und temporär intrazellulär als kompliziert aufgebaute Kristalle innerhalb von membranösen Kristallsäckehen gespeichert.Die Notwendigkeit intrazellulärer Exkretspeicherung auf Grund der Ernährungs-physiologie und Abwandlungen in der Funktionsmorphologie sowie fortschreitender Alterungserscheinungen wird diskutiert.

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Electromicroscopic studies of the guanine storage cells of Araneus diadematus Clerck (Araneae, Araneidae)

Summary Guanocytes are present in several spiders especially of the family Araneidae. The guanocytes form a compact cell-layer under the hypodermis. Their distal parts remain connected to the hypodermic hemolymph sinus, while the proximal ends establish contact with the midgut lumen in the shape of a long cellular process.The organelle equipment of the guanocytes shows that they are specialized midgut cells. They support or replace the other excretory tissues and organs especially during the reproduction period. By pinocytosis, the guanocytes remove catabolites of the purine and protein metabolism from the hemolymph, the adjacent resorption cells of the midgut, as well as from the overlying hypodermis cells. The stored catabolites are formed into complex crystals assisted by the smooth endoplasmic reticulum.The necessity of the temporary intracellular excretory storage on the basis of the physiology of nutrition, changes in the functional morphology, and general signs of old age are discussed.

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Die Untersuchungen werden dankenswerterweise von der Deutschen Forschnungsgemeinschaft durch Sach- und Personalmittel gefördert.

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Herrn Prof. Dr. H.-U. Koecke danke ich für seine Unterstützung und die Einräumung eines Arbeitsplatzes am Elektronenmikroskop.     

Scent of a Woman – The Effect of Female Presence on Sexual Cannibalism in an Orb-Weaving Spider (Araneae: Araneidae)

Post-mating sexual cannibalism occurs as a regular element of mating behaviour in a number of spider species. Frequencies of cannibalism, however, are highly variable between and within species. In Argiope bruennichi , males apparently differ in their motivation to escape a female attack but causes for this variability are unknown. We observed that the probability of sexual cannibalism is positively correlated with male age, i.e. the number of days that passed between male maturation and copulation. The mating season in this species is short with 3–4 wk and males mostly mature days before the females, whose maturation phase is longer. Consequently, as the season progresses, the availability of virgin females increases, quickly reaches a peak and then rapidly declines. In addition, the age of still unmated males increases with the season and both of these factors can potentially affect the degree of sexual cannibalism. To separate these factors, males were collected in their penultimate stage and kept until mating either with or without contact to female pheromones. Thereby, we experimentally manipulated the male's perception of female presence. Within each treatment, we formed three male age groups: (1) 2–6 d, (2) 12–16 d and (3) 22–28 d. Our results demonstrate that the probability of cannibalism was independent of male age but was explained by the treatment of males: males exposed to virgin female pheromones were significantly more likely to be cannibalised than males that were kept without female pheromones. This suggests that males change their reproductive strategy according to perceived mating prospects.     

Matriphagy in the Spider Amaurobius ferox (Araneidae,Amaurobiidae): an Example of Mother-Offspring Interactions

In the spider Amaurobius ferox, the mothers are systematically devoured by their young at a fairly constant interval. Observation of broods maintained under normal conditions showed the cannibalistic processes to be achieved within a few hours, in the course of which mothers and offspring appeared to exchange stimulation. In particular, the mothers exhibited ‘solicitation’ behaviours which appeared to activate and synchronize the young. An experiment was carried out to specify the respective role played by the two parties of the dyad in this case of matriphagy. The female's attitude towards the young (‘solicitation’, tolerance or predatory response) appeared to depend on her reproductive state. The attitude of the young towards the female (cannibalism, attraction, or flight) was shown to depend on their stage of development, but also on the female's attitude. These results support the hypothesis that, in A. ferox, matriphagy is regulated by mother-offspring interactions. Such a mechanism could ensure precise tuning of matriphagy in relation to the requirements of the young, and a certain amount of flexibility in reproduction.     

Gravity as an orientation guide during web-construction in the orb spiderAraneus diadematus (Araneae,Araneidae)

summary The effect of gravity on the web building behaviour of the common garden spiderAraneus diadematus was studied in three ways: (i) frames with partially completed vertical webs were swivelled into a horizontal position, (ii) by rotating frames with spiders in a vertical klinostat (1 rpm), and (iii) by vertically rotating a partially completed web treadmill fashion keeping the building animal in a certain position in space.(i) In the horizontal, radial wheels are not constructed, however, a more or less irregular spiral is added to a completed wheel; (ii) in the klinostat the radial wheel lacks the up/down distinction of normal webs, and the spiral is irregular; (iii) in the treadmill the spiral course is abnormal, and the degree of deviation depends on the position of the animal. If the body axis is parallel to gravity the spiral path deviates to both sides of the norm. In ag perpendicular body position the path deviates predominantly to one side, spiralling sharply inwards towards the hub. The observations suggest that the cyclic changes in the body position of spiral-buildingAraneus are an important component of the animal's orientation during this phase of web-construction.     

Selected aspects of spinning apparatus development in Araneus cavaticus (Araneae,Araneidae)

In the first half of this century, several workers observed small, seemingly glandular structures attached to the ampullate glands of spiders. Hence, they were termed accessory ampullate glands. In juvenile Araneus cavaticus, two pairs of these structures are present (starting at least with third instars), one pair attached to the major ampullate (MaA) glands and the other pair attached to the minor ampullate (MiA) glands. In adults, two pairs of accessory MaA glands and two pairs of accessory MiA glands are present. The two latter-formed pairs of accessory ampullate glands are clearly the remnants of those ampullate glands which atrophy shortly after adulthood is reached. Morphological similarities between these accessory ampullate glands and those present in juveniles provide an indication that the latter also have their origin in functional ampullate glands. A reduction in the number of ampullate glands following the last molt occurs in many spiders. The reason(s) for these reductions is unknown. In penultimate spiders close to ecdysis, we have observed that while the larger pairs of MaA and MiA glands (those that are retained in the adult) are undergoing molt-related changes which apparently render them nonfunctional, their smaller counterparts are seemingly unaffected and functional. This raises the possibility that the principal role of the smaller ampullate glands may be to assume functions during the pre-ecdysial period which are normally in the domain of the larger ampullate glands. If true, then their degeneration after the last molt would make economic sense. The presence of cylindrical spigots in juvenile females starting with fourth instars is documented.     

Size-related mating and mate guarding in the orb-web spiderNephila clavata (Araneae,Araneidae)

The orb-web spiderNephila clavata satisfies three conditions for assortative mating proposed by Ridley (The Explanation of Organic Diversity. The Comparative Method and Adaptations for Mating, Clarendon, Oxford, 1983); (1) a large male advantage in male-male competition, (2) a correlation between female size and fecundity, and (3) a long pairing duration. To test Ridley's hypothesis, size assortative mating and guarding were examined in the field. When data were pooled over time, assortative mating was found but this was due to temporal covariation of body sizes of males and receptive females. After controlling for the effect of time, size assortative guarding was not detected, although females guarded by males were larger than those not guarded in the early breeding season. Possible reasons for the absence of size assortative guarding were discussed.     

Preference for Chemical Cues Associated with Recent Prey in the Wolf Spider Hogna helluo (Araneae: Lycosidae)

In the wolf spider, Hogna helluo , we tested the response to insect and spider prey chemical cues and whether they show a preference for cues associated with prey consumed most recently. Thirty adult female H. helluo were maintained on a diet of either females of a smaller co-occurring wolf spider ( Pardosa milvina ) or domestic crickets ( Acheta domesticus ). A single P. milvina or cricket nymph was maintained on filter paper for 24 h, after which the papers from both prey sources were simultaneously presented to individual H. helluo from each diet treatment group. H. helluo locomotor behavior on each treatment and initial substrate preference was recorded (n = 15/treatment). H. helluo fed crickets showed significantly longer residence time and decreased mobility on filter paper previously occupied by a cricket; spiders fed P. milvina showed longer residence times and decreased mobility on filter paper previously occupied by P. milvina . H. helluo fed P. milvina exhibited an initial preference for substrates previously occupied by P. milvina but H. helluo fed crickets did not show a corresponding initial preference for crickets. Results suggest that H. helluo can detect distant cues associated with P. milvina but not crickets before contacting the substrate and that H. helluo respond to chemical cues from prey and show a preference for those cues associated with their most recent prey.