Search Results (18)

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

In this study, we introduce an Unmanned Aerial Vehicle (UAV) centric visual semantic simultaneous localization and mapping (SLAM) framework that integrates RGB–D cameras, inertial measurement units (IMUs), and a 5G–enabled remote interaction module. Our system addresses three critical limitations in existing approaches: (1) Distance constraints in remote operations; (2) Static map assumptions in dynamic environments; and (3) High–dimensional perception requirements for UAV–based applications. By combining YOLO–based object detection with epipolar–constraint-based dynamic feature removal, our method achieves real-time semantic mapping while rejecting motion artifacts. The framework further incorporates a dual–channel communication architecture to enable seamless human–in–the–loop control over UAV–Unmanned Ground Vehicle (UGV) teams in large–scale scenarios. Experimental validation across indoor and outdoor environments indicates that the system can achieve a detection rate of up to 75 frames per second (FPS) on an NVIDIA Jetson AGX Xavier using YOLO–FASTEST, ensuring the rapid identification of dynamic objects. In dynamic scenarios, the localization accuracy attains an average absolute pose error (APE) of 0.1275 m. This outperforms state–of–the–art methods like Dynamic–VINS (0.211 m) and ORB–SLAM3 (0.148 m) on the EuRoC MAV Dataset. The dual-channel communication architecture (Web Real–Time Communication (WebRTC) for video and Message Queuing Telemetry Transport (MQTT) for telemetry) reduces bandwidth consumption by 65% compared to traditional TCP–based protocols. Moreover, our hybrid dynamic feature filtering can reject 89% of dynamic features in occluded scenarios, guaranteeing accurate mapping in complex environments. Our framework represents a significant advancement in enabling intelligent UAVs/UGVs to navigate and interact in complex, dynamic environments, offering real-time semantic understanding and accurate localization. Full article

Programming has gained significant importance worldwide as societies increasingly rely on computer application systems. To support novices in learning various programming languages, we have developed the Programming Learning Assistant System (PLAS). It offers several types of exercise problems with different learning goals and levels for step-by-step self-study. As a personal answer platform in PLAS, we have implemented a web application using Node.js and EJS for Java and Python programming. Recently, the Flutter framework with Dart programming has become popular, enabling developers to build applications for mobile, web, and desktop environments from a single codebase. Thus, we have extended PLAS by implementing the Flutter environment with Visual Studio Code to support it. Additionally, we have developed an image-based user interface (UI) testing tool to verify student source code by comparing its generated UI image with the standard one using the ORB and SIFT algorithms in OpenCV. For efficient distribution to students, we have generated Docker images of the answer platform, Flutter environment, and image-based UI testing tool. In this paper, we present the implementation of a web-based answer platform for the Flutter Programming Learning Assistant System (FPLAS) by integrating three Docker images using Docker Compose. Additionally, to capture UI images automatically, an Nginx web application server is adopted with its Docker image. For evaluations, we asked 10 graduate students at Okayama University, Japan, to install the answer platform on their PCs and solve five exercise problems. All the students successfully completed the problems, which confirms the validity and effectiveness of the proposed system. Full article

Orb web spiders are common and highly diversified animals found in almost all habitats. They have remarkable plasticity against biotic and abiotic factors, making them excellent indicators of environmental health. The web creation behavior of spiders is influenced by disturbances in the environment. The aim of this research was to observe the alteration in the web-building behavior of Neoscona vigilans caused by human activities, specifically traffic disturbances. Spider webs were located and photographed at nighttime along the roadside, and their web characteristics were calculated. Spiders were captured from webs for their body measurements. Spider fourth leg length, carapace width, and body length had a significant association with web size and diameter, CTL, capture area, and mesh size. The quantity of trapped prey, the height of the plant, and the foliage radius increased with the distance from the road. Conversely, anchor points and web elevation from the ground dropped. The highest and lowest proportions of anomalies (modifications/defects) were recorded as holes (52.7%) in 105 webs (100%) and supernumerary (0.7%) in 55 webs (52.4%), respectively. Road disturbance had a negative influence on the spider’s behavior as the webs formed in close proximity to the road had a higher frequency of anomalies, with a gradual decrease distantly. We can gain further insight into how different environmental changes, disruptions, and pollutants lead to this imperfection in the otherwise flawless perfect structure of spider webs. Full article

Flutter has become popular for providing a uniform development environment for user interfaces (UIs) on smart phones, web browsers, and desktop applications. We have developed the Flutter programming learning assistant system (FPLAS) to assist its novice students’ self-study. We implemented the Docker-based Flutter environment with Visual Studio Code and three introductory exercise projects. However, the correctness of students’ answers is manually checked, although automatic checking is necessary to reduce teachers’ workload and provide quick responses to students. This paper presents an image-based user interface (UI) testing method to automate UI testing by the answer code using the Flask framework. This method produces the UI image by running the answer code and compares it with the image made by the model code for the assignment using ORB and SIFT algorithms in the OpenCV library. One notable aspect is the necessity to capture multiple UI screenshots through page transitions by user input actions for the accurate detection of changes in UI elements. For evaluations, we assigned five Flutter exercise projects to fourth-year bachelor and first-year master engineering students at Okayama University, Japan, and applied the proposed method to their answers. The results confirm the effectiveness of the proposal. Full article

Orb-weaver spiders produce upwards of seven different types of silk, each with unique material properties. We focus on the adhesive within orb-weaving spider webs, aggregate glue silk. These droplets are composed of three main components: water, glycoproteins, and a wide range of low molecular mass compounds (LMMCs). These LMMCs are known to play a crucial role in maintaining the material properties of the glycoproteins, aid in water absorption from the environment, and increase surface adhesion. Orb-weavers within the Cyrtarachninae subfamily are moth specialists and have evolved glue droplets with novel material properties. This study investigated the biochemical composition and diversity of the LMMCs present in the aggregate glue of eight moth-specialist species and compared them with five generalist orb-weavers using nuclear magnetic resonance (NMR) spectroscopy. We hypothesized that the novel drying ability of moth-specialist glue was accompanied by novel LMMCs and lower overall percentages by silk weight of LMMCs. We measured no difference in LMMC weight by the type of prey specialization, but observed novel compositions in the glue of all eight moth-catching species. Further, we quantified the presence of a previously reported but unidentified compound that appears in the glue of all moth specialists. These silks can provide insight into the functions of bioadhesives and inform our own synthetic adhesives. 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

In recent years, spider webs have received significant attention due to their exceptional mechanical properties, including strength, toughness, elasticity, and robustness. Among these spider webs, the orb web is a prevalent type. An orb web’s main framework consists of radial and spiral threads, with elastic and sticky threads used to capture prey. This paper proposes a bionic orb web model to investigate the energy-absorbing properties of a bionic spider web structure. The model considers structural parameters such as radial line length, radial line cross-sectional diameter, number of spiral lines, spiral spacing, and spiral cross-sectional diameter. These parameters are evaluated to assess the energy absorption capability of the bionic spider web structure. Simulation results reveal that the impact of the radial line length and spiral cross-sectional diameter on the energy absorption of the spider web is more significant compared to the radial line cross-sectional diameter, the number of spiral lines, and spiral spacing. Specifically, within a radial line length range of 60–80 mm, the total absorbed energy of a spider web is inversely proportional to the radial line length of the web. Moreover, the number of spiral lines and spiral spacing of the spider web, when within the range of 6–10 turns and 4–5.5 mm, respectively, are proportional to the total energy absorbed. A regression equation is derived to predict the optimal combination of structural parameters for maximum energy absorption. The optimal parameters are determined as follows: radial line length of 63.48 mm, radial line cross-sectional diameter of 0.46 mm, ten spiral lines, spiral spacing of 5.39 mm, and spiral cross-sectional diameter of 0.48 mm. Full article

Typical orb webs with glue droplets are renewed regularly, sometimes multiple times per night. Such behaviour, however, is rarely found with cribellate spiders. The adhesive portion of their capture threads consist of nanofibres instead of glue, and the fibres interact with the cuticular hydrocarbons (CHCs) of their insect prey for adhesion. Many of these spiders often only add new threads to their existing webs instead of completely reconstructing them. In testing the adhesion force of aged capture threads of three different cribellate species, we indeed did not observe an overall decline in adhesion force, even after a period of over a year. This is in line with the (formulated but so far never tested) hypothesis that when comparing gluey capture threads to nanofibrous ones, one of the benefits of cribellate capture threads could be their notable resistance to drying out or other ageing processes. Full article

Spiders are ubiquitous generalist predators playing an important role in regulating insect populations in many ecosystems. Traditionally they have not been thought to have strong influences on, or interactions with plants. However, this is slowly changing as several species of cursorial spiders have been reported engaging in either herbivory or inhabiting only one, or a handful of related plant species. In this review paper, we focus on web-building spiders on which very little information is available. We only find well-documented evidence from studies of host plant specificity in orb spiders in the genus Eustala, which are associated with specific species of swollen thorn acacias. We review what little is known of this group in the context of spider–plant interactions generally, and focus on how these interactions are established and maintained while providing suggestions on how spiders may locate and identify specific species of plants. Finally, we suggest ideas for future fruitful research aimed at understanding how web-building spiders find and utilise specific plant hosts. Full article

Spiders use various combinations of silks, adhesives, and behaviors to ensnare and trap prey. A common but difficult to catch prey in most spider habitats are moths. They easily escape typical orb-webs because their bodies are covered in sacrificial scales that flake off when in contact with the web’s adhesives. This defense is defeated by spiders of the sub-family of Cyrtarachninae, moth-catching specialists who combine changes in orb-web structure, predatory behavior, and chemistry of the aggregate glue placed in those webs. The most extreme changes in web structure are shown by bolas spiders, who create a solitary capture strand containing only one or two glue droplets at the end of a single thread. They prey on male moths by releasing pheromones to draw them within range of their bolas, which they flick to ensnare the moth. We used a high-speed video camera to capture the behavior of the bolas spider Mastophora hutchinsoni. We calculated the kinematics of spiders and moths in the wild to model the physical and mechanical properties of the bolas during prey capture, the behavior of the moth, and how these factors lead to successful prey capture. We created a numerical model to explain the mechanical behavior of the bolas silk during prey capture. Our kinematic analysis shows that the material properties of the aggregate glue bolas of M. hutchinsoni are distinct from that of the other previously analyzed moth-specialist, Cyrtarachne akirai. The spring-like behavior of the M. hutchinsoni bolas suggests it spins a thicker liquid. Full article

Land management of parks and vegetation complexity can affect arthropod diversity and subsequently alter trophic interactions between predators and their prey. In this study, we examined spiders in five parks with varying management histories and intensities to determine whether certain spider species were associated with particular plants. We also determined whether web architecture influenced spider occurrence. Our results showed that humpbacked orb-weavers (Eustala anastera) were associated with an invasive plant, Chinese privet (Ligustrum sinense). This study revealed how invasive plants can potentially influence certain spider communities, as evidenced by this native spider species only occurring on invasive plants. Knowing more about spider populations—including species makeup and plants they populate—will give insights into how spider populations are dealing with various ecosystem changes. While we did not assess the effect of invasive plants on the behavior of spiders, it is possible that invasive species may not always be harmful to ecosystems; in the case of spiders, invasive plants may serve as a useful environment to live in. More studies are needed to ascertain whether invasive plants can have adverse effects on spider ecology in the long term. Full article

Spiders use various combinations of silks, adhesives, and behaviors to ensnare prey. One common but difficult-to-catch prey is moths. They easily escape typical orb-webs because their bodies are covered in tiny sacrificial scales that flake off when in contact with the web’s adhesives. This defense is defeated by spiders of the sub-family of Cyrtarachninae—moth-catching specialists who combine changes in orb-web structure, predatory behavior, and chemistry of the aggregate glue placed in those webs. The most extreme changes in web structure are shown by the bolas spiders which create only one or two glue droplets at the end of a single thread. They prey on male moths by releasing pheromones to draw them close. Here, we confirm the hypothesis that the spinning behavior of the spider is directly used to spin its glue droplets using a high-speed video camera to observe the captured behavior of the bolas spider Cladomelea akermani as it actively spins its body and bolas. We use the kinematics of the spider and bolas to begin to quantify and model the physical and mechanical properties of the bolas during prey capture. We then examine why this species chooses to spin its body, an energetically costly behavior, during prey capture. We test the hypothesis that spinning helps to spread pheromones by creating a computational fluid dynamics model of airflow within an open field and comparing it to that of airflow within a tree, a common environment for bolas spiders that do not spin. Spinning in an open environment creates turbulent air, spreading pheromones further and creating a pocket of pheromones. Conversely, spinning within a tree does little to affect the natural airflow. Full article

Venom compositions include complex mixtures of toxic proteins that evolved to immobilize/dissuade organisms by disrupting biological functions. Venom production is metabolically expensive, and parsimonious use is expected, as suggested by the venom optimisation hypothesis. The decision-making capacity to regulate venom usage has never been demonstrated for the globally invasive Noble false widow Steatoda nobilis (Thorell, 1875) (Theridiidae). Here, we investigated variations of venom quantities available in a wild population of S. nobilis and prey choice depending on venom availability. To partially determine their competitiveness, we compared their attack rate success, median effective dose (ED₅₀) and lethal dose (LD₅₀), with four sympatric synanthropic species: the lace webbed spider Amaurobius similis, the giant house spider Eratigena atrica, the missing sector orb-weaver Zygiella x-notata, and the cellar spider Pholcus phalangioides. We show that S. nobilis regulates its venom usage based on availability, and its venom is up to 230-fold (0.56 mg/kg) more potent than native spiders. The high potency of S. nobilis venom and its ability to optimize its usage make this species highly competitive against native European spiders sharing the same habitats. Full article

Spiders and their webs are often used as model organisms to study a wide range of behaviours. However, these behavioural studies are often carried out in the laboratory, and the few field studies usually result in large amounts of video footage and subsequent labour-intensive data analysis. Thus, we aimed to devise a cost- and time-effective method for studying the behaviour of spiders in the field, using the now almost forgotten method of stimulating webs with tuning forks. Our study looked at the viability of using 256 Hz and 440 Hz tuning forks to stimulate, anti-predatory and predatory responses in the orb web spider Metellina segmentata, respectively. To assess the consistency of the behaviours produced, we compared these to direct mechanical stimulation with a metal wire. The results suggest that the tuning forks produce relatively consistent behaviours within and between two years in contrast to the metal wire. We furthermore found no significant effects of spider length or web area on spider reaction times. However, we found significant differences in reaction times between escape and prey capture behaviours, and between tuning forks and the wire. Thus, we demonstrated the potential of tuning forks to rapidly generate quantitative data in a field setting. Full article