Holocnemus Pluchei Research Articles

New Records of Araneae from Armenia

This study reports new records of spiders under few families from Armenia. These add to the checklist of the families Cheiracanthiidae Wagner, 1887; Eresidae C L Koch, 1845; Gnaphosidae Pocock, 1898; and Pholcidae C L Koch, 1850. The results include twelve species of which six are new records from Armenia, and include Eresus kollari Rossi, 1846; Pholcus alticeps Spassky, 1932; Holocnemus pluchei (Scopoli, 1763); Cheiracanthium erraticum (Walckenaer, 1802); Drassodes lapidosus (Walckenaer, 1802); and Aphantaulax cincta (L. Koch, 1866). Notes on the habitat and distributions are given.

The web amount and quality of web spiders (Agelenidae, Pholcidae), Agelena labyrinthica (Clerck, 1757) and Holocnemus pluchei (Scopoli, 1763), depending on food and temperature

The web amount and quality of web-weaving of two spider species, Agelena labyrinthica (Clerck, 1757) and Holocnemus pluchei (Scopoli, 1763), were determined depending on the temperature and the amount of food consumed. Two different experiments were set up in the study. In the first one, the spiders were raised at different temperatures (20-25 °C and 25-30 °C) under laboratory conditions and they were fed with 10 Drosophila melanogaster (Diptera: Drosophilidae) each time. In the second one, the spiders were fed with 7-10 insects caught from their natural habitats, at 20-25 °C and 25-30 °C. According to this, the difference in the amounts of food consumed by spiders fed with D. melanogaster at 25-30 °C was statistically significant (p < 0.05), and it was observed that these spiders (well-fed spiders) weave more frequently and regularly. On the other hand, the webs of A. labyrinthica and H. pluchei fed at lower temperatures with D. melanogaster were sparse and scarce. As a result, it was determined that the amount and quality of the cobwebs produced by both species of spiders depend on the number of nutrients and high-temperature values (25-30 °C).

Successive matings affect copulatory courtship but not sperm transfer in a spider model

Abstract Previous studies have reported that males augment their reproductive success by increasing the number of females with which they copulate, and that such copulations are not energetically demanding in terms of trivial sperm production costs. However, we now know that males do pay reproductive costs. As males mate successively, a reduction in the performance of copulatory behaviours would be expected, as well as in the number of sperm transferred. Here we compared the duration of courtship, mating and post-insemination phase, the number of genital and non-genital copulatory courtship occurrences, and the number of sperm transferred in successive matings in Holocnemus pluchei spider males. As matings increased in males, there was no effect on the duration of courtship, mating or post-insemination phase. Interestingly, genital copulatory courtship varied in successive copulations depending on male size, but there was no change in the number of sperm transferred. In addition, the occurrence of non-genital copulatory courtship decreased along successive copulations. The negative effects of successive matings on copulatory courtship indicate that these behaviours are costly for males, except for the number of sperm transferred. Our research lays the foundation for future studies on male costs as a function of mating history in spiders.

Genital movements are not restricted to spermatozoa transfer in a haplogyne spider

AbstractInternally fertilized animals are characterized by the transfer of their spermatozoa during copulation. However, the duration of copulation is highly variable, which suggests that they may serve for other functions apart from spermatozoa transfer. For example, during copulation, males can stimulate the female by using genitalic movements and/or by positioning their spermatozoa adequately within the female genitalia. In the spider Holocnemus pluchei, males perform strong squeezes and torsion movements with their pedipalps (part of their genitalia actively related to copulation) inside the female genitalia and transfer their spermatozoa during Phase I of copulation. However, the exact moment in which such transfer occurs and its relation to the pedipalp movements are still unknown. Herein, we first have identified the precise moment when the spermatozoa transfer occurs during phase I and its relation to genital movements by interrupting mating couples at the beginning, at middle and at end of this phase. Subsequently, the spermatozoa number remaining in male genitalia and stored in female genitalia were counted. We detected no relation between the number of genital movements and the spermatozoa number present in both, female and male genitalia and body size. As stated above, male genital movements serve another role during copulation in addition to spermatozoa transfer in a context of post‐copulatory sexual selection; most likely, they stimulate the female in a cryptic female choice framework.

Biological Studies on Holocnemus pluchei (Pholcidae) When Fed on Various Prey Species

Behavioral and biological studies pholcid, Holocnemus pluchei (Scopoli, 1763) (Araneae: Pholcidae) at laboratory conditions of 60 ± 70% R.H and 25 ± 2°C. were studied. Female deposited its eggs in webbing basket and carried it all around through eggs incubation period. Newly hatched spiderlings are very transparent and delicate. They stayed in the basket and molted inside or shortly after getting out of it. This spider went through six spiderlings to reach adult as female and five ones as male. First to third spiderlings were reared on Tetranychus urticae mobile stages, while later ones on Ephestia kuehniella moths and Dorsophila melanogaster. Males developed faster than females during 93.5 and 154.9 days, respectively. Life span averaged 342.6 and 130.3 days for females and males, respectively. Females’ fecundity was 68.26 eggs/female. Female produced a mean of 4.0 sacs. Intervals between egg sacs’ deposition averaged 11.2 days. Mean consumption of T. urticae was 266.9 and 217.8 from first to third spiderlings for females and males, respectively. Mean consumption of E. kuehniella and Dorsophila melanogaster was 66.8 and 56.8 individual, for females and males, respectively, during fifth spiderling to adult stage. Mean consumption of E. kuehniella and D. melanogaster was 104.6 for females, during adult stage longevity.

Copulatory behaviour increases sperm viability in female spiders

AbstractOne remarkable reproductive feature in animals with internal fertilization is a reduction in sperm viability over time in females. Whether this reduction is driven by male–male competition and/or cryptic female choice is unclear. From the perspective of cryptic female choice, we postulated that sperm viability is affected by a particular male copulatory behaviour. In this study, we investigated the following aspects: (1) sperm viability in mated females vs. males; (2) whether sperm viability varies temporally after mating; and (3) whether male copulatory behaviour covaries positively with sperm viability within females. We used the spider Holocnemus pluchei, whose males use several copulatory behaviours to court females. We found that females that stored sperm for 4 or 15 days showed no difference in sperm viability but had lower sperm viability compared with males, and males that performed a longer post-insemination behaviour had higher sperm viability inside the female. It is unclear how sperm viability is reduced and how male post-insemination behaviour affects this. It is possible that extending copulation allows males to induce females to keep sperm alive for longer. This result is predicted by theory whereby males induce females to facilitate sperm to reach and fertilize eggs based on male postcopulatory behaviour.

Female secondary sexual traits in spiders: Adaptive interpretations of the sternum projection in the pholcid Holocnemus pluchei

Sexually dimorphic traits are the outcome of a network of selective pressures acting upon each sex. While male secondary sexual traits are frequently restricted to intrasexual competition, female ornaments or weapons are mostly associated to social interactions for the access to limited resources. Here we investigate a sexually dimorphic trait expressed within the female's sternum of the spider species Holocnemus pluchei (Pholcidae), and its adaptive maintenance under the three leading hypotheses: sexual receptivity signaling, mate choice and sexual conflict hypothesis. We provide fine-scaled behavioral descriptions of the copulatory behavior of Holocnemus pluchei, corroborating that mating interactions are mediated by the female's sternum projection. The single moment of contact between the female projection and male body occurs during sperm transfer, always followed by a reduction on the intensity of the male genital movement. Additionally, biometrical properties of the female sternum projection corroborate our functional interpretation for the trait as restricting the intensity of males' copulatory movements. We claim that female sternum projection is a sexually selected trait mediating sexual conflict, with several adaptive consequences upon the sexes.

Consistency of females’ stridulatory behaviour during inter‐sexual interactions in spiders

AbstractIn a sexual context, it is expected that females base their choice of mate on the behaviours that males perform during courtship, as such behaviours are associated with the male's mate quality. Stridulation is one form of female communication in arthropods, for example, spiders. In spiders, stridulation during sexual interactions is relatively common in some groups but mainly restricted to males. In the pholcid spider Holocnemus pluchei (Pholcidae), both sexes have stridulatory organs. The aims of the present work were to: (a) determine possible differences in the frequency of occurrence of stridulation between females during inter‐sexual interactions, (b) establish female consistency in stridulation along repeated interactions and (c) analyse if female stridulation is associated with certain male behaviours during pre‐copulatory courtship and with male size. Female H. pluchei showed highly repeatable differences in their frequency of stridulation across consecutive encounters with males (ICC = 0.64). However, only a modest level of repeatability was detected in total time females spent stridulating across trials (ICC = 0.19). Females’ mean stridulatory behaviour did not change across ten consecutive trials spread across 20 days, and their behaviour was apparently unaffected by male persistence of copulatory attempted and/or size. These results imply that the frequency of female stridulatory behaviour is a trait that is highly characteristic of each individual. Finally, our work opens the door to determine whether behavioural consistency manifests in other ecological contexts and their functional implications.

Sperm viability in spiders: a first approach using Holocnemus pluchei (Scopoli, 1763) (Synspermiata: Pholcidae)

Several studies have shown that sperm viability (SV) is a key trait during sexual competition. However, this has not yet been tested in spiders as no protocol has been developed to quantify SV. Here, we describe a methodology for estimating SV using the pholcid spider Holocnemus pluchei (Scopoli, 1763). In this method, male spermatozoa were released from the sperm ducts of copulatory bulbs in 50 µl saline solution and mixed with a vortexer. Finally, 10 µl of the sperm solution were combined with 1 µl of GelRed stain. We counted a total of 200 cells and calculated the percentage that was not stained. Males showed almost 100% of live sperm inside their genital bulbs. GelRed stain demonstrated a high effectiveness to distinguish between dead and living sperm cells in spiders and it is thus a more reliable option compared to the dyes typically used, such as propidium iodide and sybr14. The high SV in H. pluchei may be explained by the multiple mating nature of females, which suggests a selection for enhanced effectiveness during sperm competition within the female genital tract.

A SCANNING ELECTRON MICROSCOPE STUDY OF SPINNING APPARATUS IN TWO SPECIES OF SPIDERS FROM GHARBIA PROVINCE (EGYPT)

The silk spinning apparatus in the spiders, Filistata insidiatrix and Holocnemus pluchei was studied with scanning electron microscopy and the main microstructural characteristics of the silk spinning tubes were described. Each of the two species possesses three pairs of spinnerets, the anterior, middle and posterior ones. The spinnerets have only three types of silk glands, which connected through the typical spinning tubes (spigots) on the spinnerets. These spigots are the ampullate, pyriform and tubuliform tubes. The arrangement, mode of distribution and the microstructure of the spigots were recorded. The distinct difference between the two studied species was the presence of a cribellum located between the anterior spinnerets in the F. insidiatrix, while the other species “H. pluchei” was devoid of this structure. The probable functions of the spigots and cribellum were discussed.

A SCANNING ELECTRON MICROSCOPE STUDY OF SPINNING APPARATUS IN TWO SPECIES OF SPIDERS FROM GHARBIA PROVINCE (EGYPT)

The silk spinning apparatus in the spiders, Filistata insidiatrix and Holocnemus pluchei was studied with scanning electron microscopy and the main microstructural characteristics of the silk spinning tubes were described. Each of the two species possesses three pairs of spinnerets, the anterior, middle and posterior ones. The spinnerets have only three types of silk glands, which connected through the typical spinning tubes (spigots) on the spinnerets. These spigots are the ampullate, pyriform and tubuliform tubes. The arrangement, mode of distribution and the microstructure of the spigots were recorded. The distinct difference between the two studied species was the presence of a cribellum located between the anterior spinnerets in the F. insidiatrix, while the other species “H. pluchei” was devoid of this structure. The probable functions of the spigots and cribellum were discussed.

Patterns of Sperm Transfer Behavior in a Pholcid Spider with Two Distinct Copulatory Phases

Sexual selection is the responsible force for the evolution and maintenance of genital diversity and function. This is the case for example, of genital movements performed by males during mating and copulation duration. Spiders perform ritualized copulations whereby males carry out different types of movements using their pedipalps with varying duration. The function and duration of these pedipalp movements is unclear. In the pholcid spider, Holocnemus pluchei males that copulate with virgin females perform two copulatory phases: phase I in which the pedipalps move and phase II in which pedipalps remain motionless. Using H. pluchei as a study species, our study aims were: 1) to assess if sperm transfer occurs when pedipalps move or are still and quantify the number of sperm in male bulbs and in the female uterus externus after copulation; and, 2) to determine if amount of sperm transferred to females is associated with duration of each copulatory phase. Two experimental groups (i. e. complete copulation and interrupted copulation) were established in which the amount of sperm remaining in the male bulbs and the amount of sperm stored by females were determined. Our results show that sperm transfer occurs during phase I, that males transfer almost all sperm from their bulbs while the females store only 20% of that male amount. There was no relation between the amount of sperm transferred or stored and the duration of the copulatory phases. These results support the hypothesis that while both phases may serve a copulatory courtship, only phase I (when pedipalps move) serves for sperm transfer.

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.

A Parental Care-Mating Dilemma? Potential Risks for Offspring in the Pholcid Spider When Egg-Carrying Females Accept Mating

Many species face a trade-off between additional mating opportunities and the offspring benefits (viability, quality) provided by parental care. Female Holocnemus pluchei spiders must abandon their egg-sac, which they otherwise carry with their chelicerae, to copulate. This may involve risks for the offspring, such as predation and fungal infection. We assessed whether (1) males discriminate between egg-carrying females according to the egg development stage, (2) females are influenced by the egg development stage in regard to their proneness to mate, and (3) offspring are less likely to survive, due to high humidity and/or predation, in the absence of egg-carrying females. Apparently, males did not distinguish between females according to the developmental stage of the eggs they carried. However, females were more likely to mate when carrying relatively mature versus immature eggs (14–18 days and 3–6 days post-oviposition, respectively). All egg-sacs hatched successfully when guarded by egg-carrying females because this avoided both fungal infections (at high humidity) and cannibalism by conspecific spiders. Thus, H. pluchei females may face a trade-off between mating and parental care. Further research should clarify why egg-carrying females mate and how females prevent their egg-sacs from being infected by fungi.

Copulatory behavior in a pholcid spider: males use specialized genitalic movements for sperm removal and copulatory courtship

Sexual selection may operate on pre-copulatory, copulatory, and post-copulatory traits. An example of a copulatory target of sexual selection is the genitalic movements a male performs during copulation. These movements may function either to prevent sperm competition or to influence a female's fertilization decision. Here we investigated how copulation duration, pedipalp movements, and abdominal movements that males of the pholcid spider Holocnemus pluchei produce during copulation influence sperm removal and/or patterns of successful sperm transfer. We compared mating events with virgin and mated females for differences in copulatory and post-copulatory behavior. We expected longer copulation duration, longer pedipalp movement duration, and more complex and frequent pedipalp and abdominal movements when males mated with mated females compared to virgin females. Except for abdominal movements, our results corroborated these predictions. Furthermore, when we investigated mating events with mated females, we observed sperm mass ejection from the female gonopore and physical removal of sperm by males' procursi. Females with interrupted second mating events showed a significant reduction of stored sperm masses compared to females with completed mating events. We suggest that males use alternating pedipalp movements to remove most of the rival sperm stored by mated females prior to sperm transfer. Copulation duration and pedipalp movements can be further used to transfer sperm and/or as a form of genitalic copulatory courtship.

Exploring the effect of the Cardinium endosymbiont on spiders

Spiders have recently emerged as important diversity hot spots for endosymbiotic bacteria, but the consequences of these symbiotic interactions are largely unknown. In this article, we examined the evolutionary history and effect of the intracellular bacterium Cardinium hertigii in the marbled cellar spider Holocnemus pluchei. We showed that Cardinium infection is primarily transmitted in spider populations maternally via egg cytoplasm, with 100% of the progeny from infected mothers being also infected. Examination of a co-inherited marker, mitochondrial DNA (mtDNA), revealed that Cardinium infection is associated with a wide diversity of mtDNA haplotypes, showing that the interaction between Cardinium and H.pluchei has a long-term evolutionary dimension and that horizontal transmission among individuals could also occur. Although Cardinium is well known to exert sex ratio distortion or cytoplasmic incompatibility in various arthropod hosts, we show, however, that Cardinium does not interact with the reproductive biology of H.pluchei. A field survey shows a clear geographical structuring of Cardinium infection, with a marked gradual variation of infection frequencies from ca. 0.80 to 0. We discuss different mechanistic and evolutionary explanations for these results as well as their consequences for spider phenotypes. Notably, we suggest that Cardinium can either behave as a neutral cytoplasmic element within H.pluchei or exhibit a context-dependent effect, depending on the environmental conditions.

Signalling and Sexual Conflict: Female Spiders Use Stridulation to Inform Males of Sexual Receptivity

The use of acoustic signals by males during courtship and mating is well known. Nevertheless, their association with female unwillingness to mate is much less studied. In spiders, stridulation during sexual interactions is relatively common in some groups, but mainly restricted to males. In the pholcid spider Holocnemus pluchei, both sexes have stridulatory organs. The aims of the present work were (1) to establish whether female stridulation occurs during intra- and inter-sexual interactions, (2) to determine whether female reproductive status affects the likelihood that she will stridulate and (3) to determine whether female stridulation is influenced by male sexual behaviour. We found that female stridulation usually occurs both during intrasexual interactions and, most frequently, during intersexual interactions. Females with more previous matings stridulated more frequently. Stridulation intensity was higher in females that did not accept new copulations compared with those that copulated. Female stridulation did not vary in elaborated and non-elaborated courtship. Thus, females use stridulation to communicate levels of sexual receptivity. It is also possible that females use stridulation to indirectly assess male ability to persist and persuade.

Karyotype, sex determination, and meiotic chromosome behavior in two pholcid (Araneomorphae, Pholcidae) spiders: implications for karyotype evolution.

There are 1,111 species of pholcid spiders, of which less than 2% have published karyotypes. Our aim in this study was to determine the karyotypes and sex determination mechanisms of two species of pholcids: Physocyclus mexicanus (Banks, 1898) and Holocnemus pluchei (Scopoli, 1763), and to observe sex chromosome behavior during meiosis. We constructed karyotypes for P. mexicanus and H. pluchei using information from both living and fixed cells. We found that P. mexicanus has a chromosome number of 2n = 15 in males and 2n = 16 in females with X0-XX sex determination, like other members of the genus Physocyclus. H. pluchei has a chromosome number of 2n = 28 in males and 2n = 28 in females with XY-XX sex determination, which is substantially different from its closest relatives. These data contribute to our knowledge of the evolution of this large and geographically ubiquitous family, and are the first evidence of XY-XX sex determination in pholcids.

Cobweb Management and Control of the Spider Holocnemus pluchei (Araneae: Pholcidae) on Buildings

The spider Holocnemus pluchei (Scopoli) (Araneae: Pholcidae) is a nonnative species commonly found in the southwestern United States. In urban areas around homes and other structures, it is often the dominant spider species on outside surfaces; requests for control of spiders and their cobwebs are common for the commercial pest management industry. We tested two physical (brushing and vacuuming) and two low-impact chemical (permethrin and botanical insecticide) spray control methods for H. pluchei on outbuildings on the University of California-Riverside campus. Forty sites containing at least two H. pluchei spiders along a 5-m section of eave or overhang were chosen for treatment. Treatment was applied within 2 d of a pretreatment census. The number of spiders per section was counted at 2, 4, 8, 12, 16, and 52 wk posttreatment. Untreated sections showed an increase in spiders through summer and a decrease in autumn. Sites treated with permethrin significantly reduced spiders >95% and had strong residual effect throughout the remainder of the sampling period. Compared with untreated controls, the three other treatments did not significantly reduce spiders; these three were similar throughout the season and were intermediate between untreated and permethrin-treated sites. In comparison with the before and 2-wk posttreatments, spiders at the untreated sites showed no difference in body sizes, whereas those in the nonpermethrin treatments showed a decrease, indicating that larger spiders were eliminated. We also tested H. pluchei spiders in the laboratory against the two insecticides used in the field studies to determine the minimum lethal concentrations for controlling H. pluchei.

Holocnemus pluchei (Scopoli, 1763) - new for Poland introduced species of pholcid spider (Araneae: Pholcidae)

Holocnemus pluchei (Scopoli, 1763) represents the family Pholcidae. Its native land is the Mediterranean region. By the end of the 20th and beginning of the 21st century this spider was introduced to West Europe where it was noted mostly in glasshouses, botanic gardens and other similar synanthropic habitats. In the presented paper the authors supplied the information about the first findings of Holocnemus pluchei on the Polish territory, which was in a large building-garden shopping center in Lublin.