Amaurobius Ferox Research Articles

The genome sequence of the Black Lace-weaver spider, Amaurobius ferox (Walckenaer, 1830).

We present a genome assembly from an individual female Amaurobius ferox (the Black Lace-weaver; Arthropoda; Arachnida; Araneae; Amaurobiidae). The genome sequence is 3,564.8 megabases in span. Most of the assembly is scaffolded into 23 chromosomal pseudomolecules, including the X 1, X 2 and X 3 sex chromosomes. The mitochondrial genome has also been assembled and is 14.24 kilobases in length.

Occurrence of the Black lace-weaver spider, Amaurobius ferox, in caves

Subterranean habitats house a wide range of species which show a number of adaptations to prevailing ecological conditions. Spiders are among the most abundant predators in caves; however, most studies on cave spiders focus on species adapted to these habitats. This is the first study related to the occurrence of the Black lace-weaver spider, Amaurobius ferox, in caves. The species lacks adaptations to the subterranean habitats and has been observed within meters from the cave entrance all year round, except in late winter until early spring. Furthermore, its occupancy is positively related to the presence of other three cave-dwelling spiders: Metellina merianae, Meta menardi and Tegenaria sp.

New data on introduced and rare synanthropic spider species (Arachnida: Araneae) in Poland (II)

Over the last decades, a large number of introduced spider species (Araneae) has been noted in Europe. Some of these newcomers have been introduced incidentally. However, the others develop permanent populations, for example in greenhouses or botanical gardens, and become synanthropic species. Introduction and synanthropization of new spider species also occurs in Poland. New records presented herein extend the list of introduced arachnofauna by seven species: Aphantaulax trifasciata, Cheiracanthium furculatum, Cyrtophora citricola, Olios argelasius, Nurscia albomaculata, Phoneutria boliviensis and Triaeris stenaspis. In addition, new posts of rarely reported so far in Poland synanthropic spiders such as: Amaurobius ferox, A. similis, Cheiracanthium mildei, Hasarius adansoni, Holocnemus pluchei, Nesticella mogera, Psilochorus simoni, Pseudeuophrys lanigera, Scytodes thoracica and Uloborus plumipes are presented. The data complement the deployment of these species in Poland as well as indicate their potential expansion routes.

Variation in group cohesion during the maternal social period of a subsocial spider

AbstractDuring the maternal social period, Amaurobius ferox spiderlings (Araneae: Amaurobiidae) show mutual tolerance, group cohesion and cooperation in prey capturing, which are recognized as the main characteristics in the evolution of spider sociality. Measuring spatial volume occupied by the spiderlings within the maternal web, this study investigated variation in group cohesion over the maternal social period, from emergence to dispersal. The results showed that the spatial volume of spiderlings varied greatly during the maternal social period and was associated with the development of the spiderlings. Strong group cohesion appeared to be related to maternal food provision, trophic egg laying and matriphagy. An increase of the spatial volume was obviously observed after matriphagy. The experiment revealed that group cohesion decreased after the second molt. A compact group of spiderlings should facilitate maternal food production at the prompted time, and reduced group cohesion after the second molt might lead to eventual dispersal of A. ferox spiderlings.

Development of locomotion in a subsocial spider

Following consumption of their mother, the subsocial spider Amaurobius ferox remain together, exhibiting distinctive behaviours in response to intruders into the natal nest. We examined the ontogeny and characteristics of locomotory behaviours in A. ferox during this post-maternal social period. Locomotion of the spiderlings, elicited by the introduction of a cricket larva into the natal web, fell into two categories: ‘abrupt locomotion’ (AL) and ‘ordinary locomotion’ (OL). AL involved rapid and linear movement, whereas OL involved slower motion, not necessarily in a straight line. Both types of locomotion varied with spiderling age. AL appeared for only a limited period of time whereas the frequency of OL increased linearly over time. AL occurred more collectively than OL: the percentage of participants in a bout of locomotion was 18.67±17.71% vs. 10.22±9.33%. The collective tendency of AL increased up until the seventh day and then decreased, whereas that of OL progressively decreased. The direction of AL responses to the intruder did not vary over time; however, for OL, movements towards increased in frequency over time. Locomotory responses also varied with the intensity of intruder movement. Including transient behaviours, the chronology of different behaviours suggests that behavioural development in A. ferox involves maternal influences and weakens group cohesion and collective tendency.

Swiss prospective study on spider bites

Knowledge of spider bites in Central Europe derives mainly from anecdotal case presentations; therefore we aimed to collect cases systematically. From June 2011 to November 2012 we prospectively collected 17 cases of alleged spider bites, and together with two spontaneous notifications later on, our database totaled 19 cases. Among them, eight cases could be verified. The causative species were: Cheiracanthium punctorium (3), Zoropsis spinimana (2), Amaurobius ferox, Tegenaria atrica and Malthonica ferruginea (1 each). Clinical presentation was generally mild, with the exception of Cheiracanthium punctorium, and patients recovered fully without sequelae. In Switzerland, spider bites generally have a benign clinical course, which is characterised by minor effects, with rapid and complete recovery. Since only verified spider bites can be regarded as spider bites, in the case of clinically important arachnidism, the spider should be sent to an expert for identification. Our study may help to diminish spider fear and reassure people who have experienced a bite.

A two year study of verified spider bites in Switzerland and a review of the European spider bite literature

During a two-year study, all spider bites recorded by Swiss primary care physicians were reported to the Swiss Toxicological Information Centre and all collected spiders were identified. A total of 14 verified spider bites were recorded, involving five species from four families: Zoropsis spinimana (five cases), Cheiracanthium punctorium (four cases), Tegenaria atrica (three cases) and one case of Malthonica ferruginea (= Tegenaria ferruginea) (both Agelenidae), and one case of Amaurobius ferox (Amaurobiidae). The bites of all spider species produced relatively mild symptoms. Local symptoms such as moderate to severe pain, circumscribed swelling and redness were the only effects in most cases. Systemic symptoms were rare. There was complete recovery in all cases and all lesions healed completely without further damage or secondary disorders. Following a review of the European spider bite literature, the number of spider species capable of biting humans in Europe is considered to be much larger than could be concluded from this study. Most spider bites are restricted to species living synanthropically, thus promoted by climate and habitat change. The annual frequency of spider bites in Switzerland is estimated at 10–100 bites per million inhabitants, but this is predicted to increase due to the continuous arrival of new alien species, many of which have a high potential to establish in urban areas.

Synchronized contractive movement of Amaurobius ferox spiderlings

During the post-matriphagy period, Amaurobius ferox spiderlings (Araneae, Amaurobiidae) show synchronous movement, contracting their bodies simultaneously. This paper describes this behavior for the first time and identifies influencing factors. The spiderlings’ contractions triggered by web vibration caused by intruders result in a strong pulsation of the whole web that a single individual would not be able to induce by itself. Repetition of the contractions was synchronized among individuals (n = 60 clutches). The movement appeared on the first day after matriphagy. The proportion of participants was maximum on the third day post-matriphagy, when on average 60.7% of the individuals were involved; thereafter the synchronicity progressively decreased. The spiderling groups performed contractions at the highest frequency on the fourth day post-matriphagy, and stopped contracting after the second molt. Experiments using mechanical stimuli produced by an electronic vibrator and a cricket’s movement showed that the vibrational intensity of the external stimuli was positively correlated with the number of contractions performed. Nestmate presence increased the number of contractions performed by individuals, and members of densely packed groups showed more contractions per individual than those in less dense groups. Contractions appeared only during the period when the mother was absent (after matriphagy, or when the mother was removed after the first molt of spiderlings and before matriphagy), and the young were not yet capable of capturing prey. Contractions may function as an antipredatory behavior.

Maternal Body-mass Transfer to Offspring in the Matriphagous Spider, Amaurobius ferox (Amaurobiidae)

The optimal strategy for semelparous females may involve adjustments in the relative investment in two fitness components, the number of offspring and the post-hatching investment per capita. To determine the pattern of maternal resource allocation to offspring in the matriphagous spider, Amaurobius ferox (Amaurobiidae), I investigated the relationship between maternal body-mass and the number of offspring, and quantified the transfer of maternal body-mass to the offspring via different forms of maternal provisioning (trophic egg-laying and matriphagy). There was a positive relationship between female body-mass and the number of offspring. However, Amaurobius mothers did not produce more trophic eggs when they had larger broods. Rather, spiderlings in larger A. ferox broods consumed larger quantities of maternal body-mass via matriphagy. Mothers transferred <TEX>$28.8{\pm}6.5%$</TEX> of their body-mass to the spiderlings via trophic egg-laying, and an estimated <TEX>$39.0{\pm}12.5%$</TEX> of their body-mass was transferred to the spiderlings via matriphagy.

Comparison of Brood Productions in the Cold-Treated Pairing vs. Not Cold-Treated Pairing in a Stenochronous Spider

To understand whether experience of cold season in reproductive behaviors in the adults of Amaurobius ferox, the paired adults of a female and a male were exposed under 'cold-treated environment' and 'not cold-treated environment', respectively. I investigated effects of the cold treatment on the brood production of A. ferox. In not cold treatment in which male-female pairs were formed in October at a temperature of <TEX>$20^{\circ}C$</TEX> (<TEX>${\pm}2^{\circ}C$</TEX>) and continuously kept under not cold-treated environment, only 3 of 50 pairs successfully reproduced (reproduction was defined as the emergence of spiderlings). In cold treatment where individuals were kept in cold conditions for 3 months prior to pair formation, 57 out of 60 couples succeeded in reproducing. Females which did not experience the low temperature displayed strong aggressiveness toward males. This behavioral inhibition might the primary barrier to copulation of A. ferox that decrease following a period of low temperature. The reproductive inhibition might help the females to allocate the maximum amount of energy in a given environment to reaching the adult stage and to delay reproduction in unfavorable wintering conditions.

Maternal Influence on Spiderlings' Emergence from the Cocoon: Observations in a Subsocial Spider

Brood caring behavior was observed in Amaurobius ferox (Araneae, Amaurobiidae), a semelparous subsocial spider, from cocoon construction until the emergence of spiderlings from the cocoon. Unlike most spiders, which emerge from cocoon by their own means, A. ferox mothers intervene in the process of the emergence of their young. I manipulated broods by removing the mother prior to emergence to determine the effects of maternal behavior on the emergence of spiderlings. My results showed that maternal intervention making the cocoon expansion and its exit, is not absolutely necessary for the emergence of A. ferox spiderlings from the cocoon. Nine clutches out of ten were able to get out of the cocoon by their own means without their mother`s help. There was no difference between control groups (`with mother`) and experimental groups (`without mother`) in the number of spiderlings that emerged ( vs. , respectfully) and in the time from the beginning to the end of emergence ( vs. hours). Time from eclosion until the emergence of the first individual in a clutch, however, was greater in the mother-absent group (3.5 days) than in the control group (2.0 days). The construction of the cocoon by the mother required always occurred in the same area within the retreat, and took approximately 6 hours, and the mother guarded the eggs during the incubation period. The emergence of the spiderlings followed a sigmoidal pattern. After emergence, the spiderlings formed a very compact group on the cocoon, which may be important in securing maternal care. The absence of cribellum and calamistrum, structures likely involved in their survival, observed in individuals of the first instar suggests that in the first stage of life, the spiderlings are dependent on their mother.

Sex Ratio and Approximate Date of Fertilization of the Subsocial Spider Amaurobius ferox Walckenaer (Araneae: Amaurobiidae)

Social spiders consistently show highly female-biased sex ratios. However, the sex ratio of subsocial spiders, which have been suggested as an intermediate stage of the evolutionary pathway towards permanent sociality, is generally unknown. We investigated the sex ratio and approximate date of fertilization of the subsocial spider, Amaurobius ferox Walckenaer (Araneae: Amaurobiidae). Investigation over 2 years revealed that sex ratio of A. ferox was consistent across years and averaged 0.49. By early May (1st 10th), 66.6% of female A. ferox observed in the field had already been inseminated, and by late May (21st 31st), 95.4% of females had been inseminated. This result suggests that A. ferox need a long time or cold temperatures to prepare them for reproduction after the developmental attainment of the adult stage.

Cooperative prey capture by young subsocial spiders: II. Behavioral mechanism

Subsocial spiders demonstrate an intermediate stage in the evolution of permanent sociality. Cooperative hunting is an important attribute of their sociality, but has not been documented in subsocial arthropods. After cannibalizing their mother, young of the subsocial spider Amaurobius ferox (Araneae, Amaurobiidae) remain together for several instars and feed communally. We monitored the collective prey capture behavior of the spiderlings. All the clutches showed collective capturing sequence (latency–orientation–moving–touching–seizing–feeding) toward the prey that was 10 times more massive than each individual. The first three individuals that exhibited attacking behavior were responsible for 90% of the total number of attacks, while 68% of the individuals within the group never exhibited attacks during the first 10 min following the introduction of prey into the communal web. First arriving individuals at the prey most often seized the antennae and legs of the prey, which probably facilitate access to the prey for subsequent individuals. The spiderlings that arrived later occupied more likely the abdomen and thorax, which contain more nutrition than the extremities occupied earlier. The individual apportionment of collective hunting behavior suggests a coordinated teamwork among individuals.

Cooperative prey capture by young subsocial spiders

Matriphagous young of a subsocial spider Amaurobius ferox exhibit collective predation during their post-maternal social period. In this paper, we examine functional mechanisms of collective predation by sibling groups. Predation efficiency increased with increasing number of individuals within each group. Solitary or paired individuals were generally unable to capture a 20 mg cricket. In larger groups, more individuals participated and captured the prey more quickly. Some siblings did not take part in paralyzing prey, but later consumed it. The proportion of these profiteers within a group increased with the group size. Presented with prey of different sizes (1, 5, or 40 mg), siblings were most aggressive towards each other when predating on 5 mg prey. Prey of this size could be captured by a single individual and yet were sufficiently large for more than one individual to eat. Siblings were much less aggressive towards one another during the capture of 40 mg prey, which require the assistance of other individuals to capture. By providing the same mass of prey in different numbers of individuals (a single cricket of 40 or 40 mg of first-instar crickets), we tested the influence of cooperation on the post-maternal social period. We found no difference in the development of young during the social period nor the timing of dispersal and the body mass of dispersing individuals. We conclude that the young of this subsocial animal increased predation efficiency by cooperative hunting after the mother's death.

L'héritage maternel d'une araignée subsociale : une toile pour la prédation collective des jeunes

Construction of a safe refuge is the first step toward the evolution of social organization in spiders. In the case of the subsocial spider Amaurobius ferox (Araneae, Amaurobiidae), the young remain in the natal nest after consuming their mother's body (matriphagy). The benefit that the young could obtain from the maternal web was investigated in their collective prey capture. The results demonstrated the adaptive value of the maternal web. The prey capturing activity was more effective when the young were allowed to stay on the maternal web than when they used the web constructed by themselves. Maternal web may also provide a better transmission of information on prey state and clutch mates' activities, because more spiderlings were recruited to contact and hold the prey in a shorter period of time than when they were on a spiderling-constructed web. The young's inheritance of the maternal nest is probably one of the crucial ways in which the mother influences the post-maternal social period of the young. To cite this article: K.W. Kim, C. R. Biologies 328 (2005).

Social facilitation of synchronized molting behavior in the spider amaurobius ferox (Araneae, Amaurobiidae)

During the social period, molting behavior of the young spider, Amaurobius ferox, is highly synchronized within the clutch. Result of the experimental study suggests that social facilitation among group members increased the synchronization. The duration of the molting period of grouped spiderlings was significantly shorter than that of individually isolated spiderlings. Involving the particular maternal strategy in food supply, this phenomenon might have adaptive values in the maintenance of mutual tolerance among the siblings by decreasing the interindividual difference in development and in the avoidance of cannibalism on molting individuals. This probably will also serve to make the peaceful collective behaviors of the spiderlings in matriphagy and cooperative prey capture during their social period.

Dispersal behaviour in a subsocial spider: group conflict and the effect of food availability

This study investigates proximate factors influencing dispersal behaviour in the subsocial spider Amaurobius ferox. Dispersal of spiderlings from the natal web occurred as a progressive sigmoidal function (mean duration of dispersal period=31 days), with considerable individual variability in developmental instar and body mass within the clutch at the time of dispersal. The spiderlings showed a significant decrease in group cohesion on the 6th day after their second moult, which corresponded to the beginning of the dispersal period. Mutual aggressiveness appeared when the spiderlings began to show predatory behaviour (4th day post-second moult) and increased over the course of the dispersal period. While lack of prey in the maternal nest accelerated dispersal behaviour, the addition of prey items lengthened the dispersal period in previously non-fed clutches. Individuals that dispersed were smaller than the remaining individuals when measured on the day 50% of the clutch had dispersed. Timing of the appearance of the developmental characters (second moult, predation activity, agonistic behaviour against siblings, reduction of group cohesion, dispersal) suggests that the dispersal trait might have evolved in consequence of these different functional behaviours.

Trophic egg laying in the spider, Amaurobius ferox: mother–offspring interactions and functional value

Offspring of the spider Amaurobius ferox (Araneae, Amaurobiidae) were provided with trophic eggs of their mother the day after their emergence from the egg sac. This precisely timed egg laying followed after a series of mother–offspring interactions involving specific behaviors. Experiments showed that the trophic egg laying of the mother (providing she is in the appropriate reproductive condition) necessitated not only their presence, but also the stimulating behavior of the spiderlings. By stimulating their mother the spiderlings actually inhibited the normal maturation of the second generation of maternal eggs and prompted the release. Comparing to the trophic egg-deprived clutches, the clutches provided with the trophic eggs developed with higher body mass, earlier moulting and matriphagy. More offspring survived at the matriphagy with the mother normally provisioning the first clutch with trophic eggs rather than with the mother that did not produced the trophic eggs for her first clutch but for her second clutch. By turning her potential second generation into food, the mother increases her reproductive success.

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

AbstractIn the spiderAmaurobius 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, inA. 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.

The hydraulic interaction between prosoma and opisthosoma in Amaurobius ferox (Chelicerata, Araneae)

Experiments are described which demonstrate that blood moves from the prosoma into the opisthosoma in Amaurobius ferox when the spider is held on a plasticine block and is stimulated with a small brush. This movement of blood is also seen during bouts of struggling when the spider is trying to free itself. The return flow of blood from the opisthosoma is to a large extent due to the pumping action of the heart. It is proposed that the locomotory exhaustion shown by artificially stimulated spiders is due to this loss of blood from the prosoma which leads not only to hydraulic insufficiency, but also to a lack of oxygen through interruption of the normal blood flow.