Search results for "Spider"
showing 10 items of 97 documents
Costs of courtship and mating in a sexually cannibalistic orb-web spider: female mating strategies and their consequences for males
2002
The costs of courtship and mating may include increased risks of predation, the transmission of pathogens, and a loss of foraging opportunities. Thus, a female's decision to tolerate a courting male will depend upon how these costs offset the benefits of mating, which will depend on her reproductive and nutritional status. While these costs may be similar for mated and unmated females, the benefits of mating will be less for mated than virgin females. However, the cost of lost foraging opportunities may be higher for females with fewer nutritional reserves necessary for forming eggs. We examined how these costs and benefits influence the courtship and mating behaviour of male and female orb…
Knowing the Risk: Crickets Distinguish between Spider Predators of Different Size and Commonness
2013
Predators unintentionally release chemical and other cues into their environment that can be used by prey to assess predator presence. Prey organisms can therefore perform specific antipredator behavior to reduce predation risk, which can strongly shape the outcome of trophic interactions. In contrast to aquatic systems, studies on cue-driven antipredator behavior in terrestrial arthropods cover only few species to date. Here, we investigated occurrence and strength of antipredator behavior of the wood cricket Nemobius sylvestris toward cues of 14 syntopic spider species that are potential predators of wood crickets. We used two different behavioral arena experiments to investigate the infl…
DISPERSAL OF STEGODYPHUS DUMICOLA (ARANEAE, ERESIDAE): THEY DO BALLOON AFTER ALL!
2001
Abstract There has been some controversy about whether adult females of social Stegodyphus disperse by ballooning. Here we show that adult Stegodyphus dumicola (Eresidae) Pocock 1898 are able to gain up-lift by releasing a very large number of threads. The threads fan out widely from the spider's body and form a triangular sheet. This previously unknown ballooning mechanism, enables even large spiders to disperse over large distances.
Sparassidae of Japan. I. New Species of Olios, Heteropoda, and Sinopoda, with Notes on Some Known Species (Araneae: Sparassidae: Sparassinae and Hete…
2000
Four new species of the spider family Sparassidae are described from Japan under the names Olios japonicus sp. nov., Heteropoda simplex sp. nov., Sinopoda okinawana sp. nov. and S. tanikawai sp. nov. The genus Olios is recorded for the first time from Japan. Taxonomical notes and new records of some known species and comments on diagnostic characters of the subfamilies and genera of the Japanese Sparassidae are presented.
Overwintering survival in relation to body mass in a field population of the wolf spider ( Hygrolycosa rubrofasciata )
1999
Body size is often considered to be an important trait affecting individual fitness. In arthropods, females commonly benefit from larger size directly through increased fecundity (Roff, 1992), and males through increased mating success (Andersson, 1994). It has also been suggested that larger individuals may in general have a better survival than smaller individuals (Calder, 1983; Peters, 1983). From this suggestion it may be predicted that during stressful environmental conditions larger individuals should do better than smaller individuals.
First records of the genera Pseudopoda, Sinopoda, and Olios from Taiwan with descriptions of four new species (Araneae: Sparassidae)
2001
Four new species of the spider family Sparassidae are described from Taiwan: Pseudopoda serrata sp. nov. (male and females), Pseudopoda recta sp. nov. (female), Sinopoda exspectata sp. nov. (male), and Olios scalptor sp. nov. (male). These represent first records of the three genera for Taiwan. A record of Heteropoda venatoria (Linne 1767) is also reported.
EVIDENCE FOR KIN-STRUCTURED GROUP FOUNDING AND LIMITED JUVENILE DISPERSAL IN THE SUB-SOCIAL SPIDER STEGODYPHUS LINEATUS (ARANEAE, ERESIDAE)
2001
Abstract In sub-social spiders, restricted dispersal of young (i.e., natal philopatry) and the potential for inbreeding could contribute to within-population subdivision, thus resulting in a population structure similar to that found in social congeners. In this context, we analyzed the origin and mode of individual distribution patterns and their contribution to within-population structure in juveniles of the sub-social spider Stegodyphus lineatus. We investigated the distribution of juveniles for four months after leaving the maternal nest using allozyme genetic markers. We found that isolated groups of juveniles consisted predominantly of siblings, whereas larger aggregations of individu…
Survival strategies of the crab spider Thomisus onustus Walckenaer 1806 (Chelicerata, Arachnida, Thomisidae).
1989
The initial energy supply of emerging spiderlings is relatively meagre, so survival without feeding on insects during a spell of bad weather is limited to a period of a few days or weeks. During our investigations, spiderlings of Thomisus onustus (Arachnida, Thomisidae) were kept on different diets. There was a significant difference in survival rate between spiderlings that were starved or fed on pollen, “nectar”, or Drosophila. The results showed that pollen and nectar can be a source of energy for spiders for an extensive period. This demonstrates another way in which spiders may survive starvation when insect prey is lacking and thus ensure the survival of a whole population.
A TEST FOR REPRODUCTIVE SEPARATION OF ALTERNATE GENERATIONS IN A BIENNIAL SPIDER, ARANEUS DIADEMATUS (ARANEAE, ARANEIDAE)
2002
In Denmark, two seemingly distinct size-classes, 3rd and 4th instar juveniles and repro- ductive adults, of Araneus diadematus are found during every breeding season in autumn, indicating a non-overlapping biennial life-cycle. We tested the hypothesis that alternate generations might experience a degree of reproductive isolation, using the distribution of nuclear (allozyme) and maternal (mtDNA) genetic markers. Individuals of a locality behaved as belonging to a random mating population, irrespective of size. No differences were found between any size-class pairs, within and between 2 yr, or among geographically distant samples. Processes that may lead to this result are discussed: the bien…
Detection of the Spider Predator, Hololena Nedra By Naïve Juvenile Field Crickets (Gryllus Integer) Using Indirect Cues
2004
Summary In many species, prey detect predators using chemical cues, which may be based on the predator’s previous diet. Furthermore, the predator’s previous hunting strategy and diet may affect the prey’s behavioural strategies to avoid predation. Juvenile Gryllid field crickets face predation by spiders, but the responses of juvenile crickets to spiders are unknown. We studied whether naive juvenile field crickets can detect a predatory spider, Hololena nedra, using chemotactile cues (silk, secretions and excreta). We also studied the effect of the predator’s diet on the juvenile field cricket’s anti-predator behaviour. Cricket nymphs avoided the chemotactile spider cues when the spiders w…