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Deinopidae spiders are known mainly for their web-building behavior and prey-capture strategy. However, studies on their population ecology are scarce. Therefore, we evaluated the population fluctuation, phenology, and diet of Deinopis cf. cylindracea. We also investigated how abiotic (precipitation and temperature) and biotic (prey availability) factors influence the abundance of this species. Our results showed that D. cf. cylindracea has an annual cycle with a maximum density in March. The reproduction cycle occurs from March to July. The recruitment of spiders occurred between July and October, followed by a peak of young individuals in December, juveniles in February, subadults in April, and adults in May, indicating a 'fall stenochronous' phenological pattern. The climatic variables were important factors that influenced the fluctuation of the age of D. cf. cylindracea. Although we did not find a positive correlation between the climate and its abundance at time 0, we did observe a correlation with a delay of three months. The main preys were Formicidae and Coleoptera, and not all available preys were part of the spiders' diet. These results indicate that the spiders require time to respond to changes in environmental conditions and provide information about the different stages of development over time. [ABSTRACT FROM AUTHOR]

Body coloration of orb-web spiders was previously hypothesized to be attractive to insects, luring potential prey, or associated with protection against visually oriented predators. We combined manipulative experiments with spectral reflectance analyses to test the prey attraction hypothesis, using the araneid spider Gasteracantha cancriformis as a model. The study was conducted in a shaded environment, within a forest fragment of the Atlantic forest located in Southeastern Brazil. Insect interception on web surfaces displaying the dorsal section of G. cancriformis opisthosoma, which emits blue fluorescence and reflects light in the ultraviolet wavelength region, was higher than on surfaces displaying the spider's ventral section, or in webs without spiders. This study supports the prey attraction hypothesis by providing evidence that the color patterns of G. cancriformis dorsum improve prey interception by their webs. Fluorescence and achromatic cues are probably important to lure and attract potential prey. [ABSTRACT FROM AUTHOR]

Protandry occurs when males mature prior to females in the breeding season. There may be a fitness benefit for males if they are able to copulate and defend virgin and more fecund females. Therefore, fitness benefits can be investigated by studying assortative mating during mate guarding of virgin females before and after female sexual maturation. The asynchrony of female development in the protandrous spider Manogea porracea (Araneidae) provides an opportunity to investigate how female sexual maturity (subadult and adult females) influence size-assortative pairing. We investigated size differences between couples composed of males and subadult females, and of males and adult females. We hypothesized that size-assortative pairing is stronger in couples with adult females. Adult females were larger than subadults, but the size of males paired with females from both groups was similar. We found assortative pairing within all couples involving an adult female. However, this pattern was not observed among couples with subadult females. It is possible that the production of sexual pheromones by adult females after their last molt intensifies male intrasexual competition, promoting positive assortative pairing. We discuss the potential mechanisms affecting male mate choice and mate competition during pairings in M. porracea. [ABSTRACT FROM AUTHOR]

Niche theory suggests that the coexistence of ecologically similar species in the same site requires some form of resource partitioning that reduces or avoids interspecific competition. Here, from July 2013 to December 2015, we investigated spatial niche differentiation at three different scales of two sympatric congeneric spiders, Peucetia rubrolineata and P. flava, along an altitudinal gradient in shaded and open areas in an Atlantic forest in Serra do Japi, SP, Brazil. These spiders are peculiar in that they present an exclusive association with the plant Trichogoniopsis adenantha (Asteraceae). In theory, the coexistence of two Peucetia species could be explained by: (1) microhabitat segregation with individuals from different species occupying different parts of the same plants; (2) mesohabitat segregation with different species using plant in different environments; (3) macrohabitat segregation, where different species would not co-occur along the altitudinal gradient. With respect to micro-habitat use, in both species, different instars used different plant parts, while the same instars of both species used the same type of substrate. However, the two Peucetia species segregated by meso-habitat type, with P. rubrolineata preferring T. adenantha plants in shaded areas and P. flava preferring those in open areas. Our results support the hypothesis of niche partitioning begetting diversity, and highlight the importance of analyzing habitat use at multiple scales to understand mechanisms related to coexistence. [ABSTRACT FROM AUTHOR]

The balance between the investment of time and energy by males in searching for new partners and in protecting and/or feeding offspring can influence reproductive strategies. Strong competitors may enhance their mating effort, while weak competitors may compensate their disadvantage in intrasexual competition by investing in the increase of offspring survival. This balance and its implications to male reproductive strategies have been extensively investigated in vertebrate species but remain poorly understood in invertebrates, because paternal care is rare. Manogea porracea is the only described solitary spider in which extended male care occurs in the absence of females (i.e. amphisexual care). Large males usually win disputes and prefer large, more fecund females. Therefore, they may increase their reproductive success by prioritizing the investment in the search for additional partners, while small males may compensate their competitive disadvantage by increasing their own parental efforts. We tested the prediction that lighter males will invest in the care of the offspring more often than heavier ones. However, our results indicate that males care for offspring regardless of their size. We discuss how the benefits of parental care may override the costs of reducing the number of potential mates for M. porracea males and suggest new directions for further studies. [ABSTRACT FROM AUTHOR]

Epipompilus Kohl comprises 52 species of wasps that are parasitoids of spiders; 16 species occur in the Neotropical region and 36 species occur in the Australian region. The biological knowledge of this genus is limited and its interactions and host spiders are still incipient. Here, we report some behavioural and biological characteristics of E. excelsus, a parasitoid of the tube-dwelling spider Ariadna mollis. We observed an E. excelsus female attacking an adult female of A. mollis in São Paulo, Brazil. We photographed daily the larval development of the wasp, from the egg stage to adult emergence. The entire developmental cycle of the wasp took 24 days. This period was shorter than the developmental periods of wasps belonging to other genera of Pompilidae. Although all species within Pompilidae use spiders as host, they present great behavioural diversity, characterized by different ethological sequences. In conclusion, this study demonstrated that the Neotropical species of Epipompilus exhibit biological characteristics similar to the Australian species, acting as a koinobiont ectoparasitoid, but displays differences in larval morphology. Studies on other species could elucidate the extent of these differences and similarities, contributing to our understanding of the evolutionary history of Epipompilus, and consequently of Pompilidae. [ABSTRACT FROM AUTHOR]

Numerous phenological studies on spiders belonging to the families Oxyopidae, Thomisidae, Lycosidae, Selenopidae (e.g.Selenops cocheleti) and Salticidae (e.g.Psecas chapodaandPsecas viridipurpureus) have been conducted in the neotropical region. However, studies that simultaneously compare population dynamics and age structure in populations of sympatric species are limited, especially in Oxyopidae. The population dynamics and phenology of two congeneric lynx spider (Peucetia rubrolineataandPeucetia flava) were examined in southeastern Brazil. Several characteristics of the age structure were compared between the two spider species. The variation in the total abundance of individuals and age structure and their relationship with climatic variables were similar between the two spiders. Adults of these spiders were present mainly in spring, indicating an annual reproductive cycle and a ‘stenochronous spring’ phenological pattern. The recruitment of spiders occurred in summer forP. rubrolineataandP. flava, followed by successive phenological peaks at all stages of development. Rainfall and temperature had a positive correlation to population flux in the two spider species studied. Despite the significant climatic effects observed in the Serra do Japi, the phenological pattern of the population in this study was not always repeated in other species of spiders (e.g.Selenops cocheleti). [ABSTRACT FROM AUTHOR]

Optimal escape models assume that decisions to escape after a predation attempt depend on the initial risk assessment. However, few studies have explored animals' decisions to return to normal activities after their first escape and how the ecological context influences these behaviours. To address these gaps, we investigated the influence of substrate type on escape behaviour and refuge use in the spider Aglaoctenus castaneus. Individuals forage on sheet webs but hide in funnels after detecting potential threats. Spiders from two populations build webs either on injurious substrates that can harm predators or on noninjurious substrates. The dominant injurious substrates include a large thorny palm species in the 'thorny palm' population and a razor grass in the 'razor grass' population. We hypothesized that spiders constructing webs on injurious substrates would (1) display reduced sensitivity to approaching predators by hiding in their funnels and (2) would return to their sheet web more quickly after detecting a predator. We also assessed whether these behaviours were correlated across and within populations and whether they were affected by the social context (couples or solitary individuals). Spiders inhabiting injurious substrates exhibited shorter flight initiation distances (FIDs) compared to those inhabiting noninjurious substrates. Interpopulation variation was observed, with spiders from the thorny palm population displaying shorter FID and lower hiding time than those from the razor grass population. However, there was no correlation between FID and hiding time. Spiders from the thorny palm population showed less sensitivity to predators, probably because thorny palm location was safer than the razor grass location. In conclusion, A. castaneus can adjust risk-taking behaviours depending on the damaging potential of the substrate for predators. We propose new hypotheses with the aim of improving risk assessment research. • We investigated the effects of substrate type on risk assessment of A. castaneus. • We observed spiders in two populations: thorny palm vs razor grass dominant. • Spiders on injurious substrates had shorter flight initiation distances (FIDs). • Hiding time was not correlated with FID. • Spiders in the thorny palm population had shorter FIDs and hiding times. [ABSTRACT FROM AUTHOR]

In this study, the population fluctuations, phenology and sex ratio of the bromeliad-dwelling jumping spider Psecas chapoda were investigated in an area of semi-deciduous forest in south-eastern Brazil. Psecas chapoda occurred and reproduced on Bromelia balansae (Bromeliaceae) throughout the year. The number of egg sacs increased at the beginning of the rainy season (September to December), but the population size and phenology were stable over time and correlated weakly with rainfall and temperature. The principal factor affecting the dynamics of P. chapoda was the blooming of B. balansae , which expelled spiders because of the drastic change in plant architecture. Male spiders were more frequent than females during the juvenile phase, whereas females were more frequent than males during the subadult and adult phases, suggesting a sex ratio that favoured males. The biotic and abiotic factors that influence the population dynamics and sex-dependent vulnerability determination are discussed. [ABSTRACT FROM AUTHOR]

Spiders exhibit various egg sac construction behaviors using camouflage to protect the eggs from predators and parasitoids and also perform parental care to increase offspring survival. In this study, we describe the egg sac construction behavior of Deinopis cf. cylindracea, and the camouflage characteristics of egg sac when left without the female’s active protection. Our observations showed that D. cf. cylindracea builds a fairly compact egg sac, with an outermost layer composed of dense silk. This outermost layer is dark brown, perhaps to camouflage with the substrate on which the egg sac is deposited. Moreover, females tend to hide their egg sacs with dry leaves in the litter. In addition, the overall color, shape, and size of the egg sac resemble the dry seeds of Plinia cauliflora, the plant on which D. cf. cylindracea was found. Two female spiders were positioned on their egg sacs; however, whether this behavior reflects maternal care remains unknown. Therefore, the overall egg sac construction behavior of D. cf. cylindracea may be related to a strategy for increasing fitness. This is the first behavioral record for a South American deinopid species. [ABSTRACT FROM AUTHOR]

Spiders exhibit various egg sac construction behaviors using camouflage to protect the eggs from predators and parasitoids and also perform parental care to increase offspring survival. In this study, we describe the egg sac construction behavior of Deinopis cf. cylindracea, and the camouflage characteristics of egg sac when left without the female's active protection. Our observations showed that D. cf. cylindracea builds a fairly compact egg sac, with an outermost layer composed of dense silk. This outermost layer is dark brown, perhaps to camouflage with the substrate on which the egg sac is deposited. Moreover, females tend to hide their egg sacs with dry leaves in the litter. In addition, the overall color, shape, and size of the egg sac resemble the dry seeds of Plinia cauliflora, the plant on which D. cf. cylindracea was found. Two female spiders were positioned on their egg sacs; however, whether this behavior reflects maternal care remains unknown. Therefore, the overall egg sac construction behavior of D. cf. cylindracea may be related to a strategy for increasing fitness. This is the first behavioral record for a South American deinopid species. [ABSTRACT FROM AUTHOR]