Search Results (8)

Spiders and other arthropods can sometimes consume others of their kind, and this is most often associated with mating activity, whereby females cannibalize males during or after mating, or during mating attempts. Nonsexual cannibalism is less common but may be associated with food availability or territorial aggression. In the Southeastern United States, a non-native orb-weaving spider, Trichonephila clavata (the “jorō spider”), is expanding its range. Prior lab experiments indicated this species to be “shy” compared to other native spiders, based on behavioral reactions to stimuli. Here, we report descriptive observations and photo-documentation of nonsexual cannibalism by this species, including from anecdotal observations, plus findings from controlled pairings of spiders, both in the lab and in natural webs in the field. In the cases where cannibalism was witnessed, it involved one female biting and killing another, typically after a short fight. When two females of a similar size were placed together in a container (n = 25 trials), fights ensued 40% of the time. When females of different sizes were paired (n = 27 trials), fights happened 18% of the time, and the larger females were not always the aggressor. Across all the lab trials (n = 52), six bouts (9%) led to the direct killing of one female. In field trials where two females were placed on an empty web (n = 14 trials), we observed one fight (7%) where the aggressor ended up killing and wrapping the other spider in silk. Given that some of these instances happened away from any web, these observations imply that the aggression is not necessarily an act of territoriality. The intraspecific aggression could arise when females are provoked or stressed, which deserves more study. Full article

The Jorō spider (Trichonephila clavata (L. Koch): Araneae: Araneidae), an invasive species from Asia, and native orbweaving spiders were censused at 25 forest sites in the Atlanta, Georgia, region at the forefront of the Jorō spider’s spread from 2022 through 2024. The Jorō spider was found in all 25 sites in all three years, doubling in abundance each year. In 2022, the number of Jorō spiders found was 444 or 16.34 per hour of census. This doubled in 2023 to 859 or 30.54 per hour. The Jorō numbers doubled again in 2024 to 1713 or 59.14 per hour. This contrasts markedly with the seven species of native orbweavers found during the censuses, which declined by ca. 40% each year. In 2022, 52 or 1.72 individuals per hour of six native orbweaver species were found at 18 sites. In 2023, the number dropped to 32 or 1.06 individuals per hour of six species found at 11 sites. In 2024, the number further declined to 18 or 0.55 individuals of six species found at eight sites. The Jorō spider’s spread and rapid increase in abundance may disrupt trophic networks and negatively influence the abundance of both native orbweavers and flying insect species. Full article

Cadmium (Cd) is a pervasive heavy metal pollutant released into the environment through industrial activities such as mining, smelting, and agricultural runoff. This study aimed to investigate the molecular and metabolic impacts of Cd exposure on the silk glands of Trichonephila clavata, a species renowned for producing silk with exceptional mechanical properties. Cd accumulation in spider bodies and silk glands was significantly higher in the low- and high-Cd groups compared to controls, with a dose- and time-dependent increase. Oxidative stress markers, including superoxide dismutase, glutathione peroxidase, peroxidase, and malondialdehyde, were significantly elevated, indicating a robust stress response. Proteomic analysis identified 2498 proteins, with 227 differentially expressed between Cd-treated and control groups. Key metabolic pathways, including glutathione metabolism, cysteine and methionine metabolism, and amino acid biosynthesis, were significantly disrupted. Downregulation of enzymes such as glutathione synthase and S-adenosylmethionine synthetase highlighted oxidative imbalance and impaired sulfur metabolism, indicating disruptions in redox homeostasis and energy metabolism critical for silk production. These findings demonstrate that Cd exposure alters oxidative stress responses, disrupts key metabolic pathways, and impairs silk gland functionality at multiple molecular levels. This study advances the understanding of the impact of heavy metal stress on spider physiology and provides a foundation for further research on the ecological implications of Cd contamination. Full article

An invasive spider from East Asia has established in the U.S. southeast (the “jorō spider,” Trichonephila clavata) and is rapidly expanding its range. Studies assessing the impact of this species are needed, including how expansive its diet is. An open question is whether monarch butterflies, Danaus plexippus, are a potential prey item for this spider, given that jorō spiders do not coexist with monarchs in their native range. Since monarch larvae feed on milkweed, they sequester cardiac glycosides into their adult tissues, rendering them unpalatable to many predators. At sites within northeast Georgia, we staged a series of trials (n = 61) where we tossed monarchs into jorō spider webs and, for comparison, performed similar trials with another aposematic species, gulf fritillary (Agraulis vanilla), and a palatable species, tiger swallowtail (Papilio glaucus). We recorded the outcome of the trials, which included whether the spider attacked or did not attack the prey. We also conducted a visual survey during the same fall season to look for evidence of jorō spiders consuming monarchs naturally. Our findings revealed that jorō spiders avoided eating monarchs; spiders only attacked monarchs 20% of the time, which was significantly less than the attack rates of similarly sized or larger butterflies: 86% for gulf fritillaries and 58% for tiger swallowtails. Some jorō spiders even removed monarchs from their webs. From our visual surveys of the surrounding area, we found no evidence of natural monarch consumption and, in general, butterflies made up only a fraction of the jorō spider diet. We conclude that jorō spiders appear to recognize monarch butterflies as being unpalatable, even without having a prior history with the species. This invokes questions about how these spiders can immediately recognize their unpalatability without touching the butterflies. Full article

An invasive orb-weaving spider from east Asia is now spreading through the southeastern United States; Trichonephila clavata (the “jorō spider”) makes large, imposing webs seemingly everywhere, including in urban landscapes, and even next to busy roads. However, areas near roads come with frequent disturbances, including auditory and vibrational, which for many animals, leads to physiological or behavioral changes. Here we tested if varying levels of road traffic affect the prey–capture behavior of jorō spiders in northeast Georgia. We visited roadsides that ranged in traffic density and exposed nearby jorō spiders to a simulated prey (a tuning fork at 128 hz frequency, touched to the web), and recorded whether or not the spider attacked it. Out of 357 total trials across 20 different roads, jorō spiders attacked the simulated prey 59% of the time, but at the local scale, there was high variability in this rate; at some roadsides, over 80% of the spiders attacked, while at others, less than 30% did. When all roads were considered collectively, there was a small but significant (negative) correlation between daily road traffic and spider attack rates. Put another way, spiders near moderate- to heavy-traffic roads were slightly less likely to attack than those near low-traffic roads (51% vs. 65%). Jorō spiders appear to be able to live near roads, but this does come with a cost in terms of prey capture. However, spiders near busier roads did not weigh less than those in other sites, suggesting they may be able to compensate for the disturbance. These findings add to the accumulating evidence around this species that points to its ability to exist in human-dominated landscapes, which will likely aid its spread in the introduced range. Full article

The jorō spider (Trichonephila clavata, originally from east Asia) has been introduced in the southeastern United States, and is rapidly expanding this range, leading to questions about what facilitates this spread. Meanwhile, its cousin, the golden silk spider (T. clavipes), already has a range that covers most of the southeast. In an ongoing effort to understand the behavior of jorō spiders in their introduced range, we undertook the current project to evaluate how they react to perceived threats, which can inform us on how a species interacts with conspecifics, or how well it can tolerate anthropogenic disturbances. We collected mature females of both Trichonephila species, plus three locally common orb-weaving species in Georgia, and we evaluated the time spent immobile after experiencing a mild disturbance (a brief puff of air). We also collected similar “air puff response” data for five other North American species from the published literature. Collectively, the dataset totaled 453 observations of freezing behavior across 10 spider species. Comparing these data across species revealed that most spiders remained immobile for under a minute after the stimulus. Meanwhile, both Trichonephila spiders remained immobile for over an hour, which appears to be unprecedented, and suggests that spiders in this genus are the “shyest” ever documented. This reaction could also allow Trichonephila spiders to tolerate urban environments by remaining motionless throughout each disturbance instead of fleeing. Full article

An invasive spider (Trichonephila clavata [L. Koch 1878], or jorō spider) is rapidly expanding throughout the southeast of the United States, engendering many questions about how native fauna will be affected. Here, we describe an observation of a northern cardinal (Cardinalis cardinalis, L.) consuming prey items from a jorō web, which serves as an example of a native species deriving a (small) benefit from this new invader. Moreover, the manner of the kleptoparasitism is also noteworthy; the cardinal perched directly on the web, which supported its weight (which is 42–48 g in this species). This appears to be the first documented case of a spider web supporting a perching bird. We also include measurements of other jorō webs, where web strength had been assessed using a force gauge, which revealed that typical webs can support masses up to 70 g before collapsing. Collectively, this information adds to the small but growing body of knowledge about the biology of this non-native spider. Full article

Spider silk is a natural fiber with remarkable strength, toughness, and elasticity that is attracting attention as a biomaterial of the future. Golden orb-weaving spiders (Trichonephila clavata) construct large, strong webs using golden threads. To characterize the pigment of golden T. clavata dragline silk, we used liquid chromatography and mass spectrometric analysis. We found that the major pigment in the golden dragline silk of T. clavata was xanthurenic acid. To investigate the possible function of the pigment, we tested the effect of xanthurenic acid on bacterial growth using gram-negative Escherichia coli and gram-positive Bacillus subtilis. We found that xanthurenic acid had a slight antibacterial effect. Furthermore, to investigate the UV tolerance of the T. clavata threads bleached of their golden color, we conducted tensile deformation tests and scanning electron microscope observations. However, in these experiments, no significant effect was observed. We therefore speculate that golden orb-weaving spiders use the pigment for other purposes, such as to attract their prey in the sunlight. Full article