scholarly journals Sand throwing in a pit-building antlion larva from a soil mechanical perspective

2020 ◽  
Author(s):  
Sebastian Büsse ◽  
Thies H. Büscher ◽  
Lars Heepe ◽  
Stanislav N. Gorb ◽  
Hans Henning Stutz
Keyword(s):  
Prey Item ◽  
Slope Angle ◽  
Pitfall Trap ◽  
Unstable State ◽  
Pitfall Traps ◽  
Unstable Condition ◽  
Element Analysis ◽  
Abiotic Environment ◽  
Insect Larva ◽  
New Hypothesis

AbstractSandy pitfall traps are an elaborate construction to capture prey and antlions are well-known representatives of this predation technique. From a soil mechanical perspective, antlions exploit the interactions between the particles of their habitat and engineer a stable trap. This construction is close to the unstable state, where a prey item will immediately slide towards the center - towards the ambushing antlion - when accidently entering the trap. This method is efficient, but requires permanent pit maintaining. According to the present knowledge, antlions throw sand at their prey, to distract it, and/or cause sand slides towards the center of the pit. Using sand throwing and escape experiments, as well as finite element analysis, we supported this hypothesis. Furthermore, we added new hypothesis about maintaining the pitfall trap. We showed that sand that accumulates in the center of the pit will be continuously removed, which lead to the slope maintenance close to an unstable condition. This avoids self-burial of the antlion, as well as decreasing the chance of prey item escapes by keeping the slope angle steep. This demonstrates the interaction of an insect larva with its abiotic environment from a novel perspective and adds further insights into longstanding entomological hypotheses.

Sand-throwing behaviour in pit-building antlion larvae: insights from finite-element modelling

2021 ◽  
Vol 18 (182) ◽  
pp. 20210539
Author(s):  
Sebastian Büsse ◽  
Thies H. Büscher ◽  
Lars Heepe ◽  
Stanislav N. Gorb ◽  
Hans Henning Stutz
Keyword(s):  
Finite Element ◽  
Laboratory Experiments ◽  
Slope Angle ◽  
Pitfall Trap ◽  
Present Knowledge ◽  
Unstable State ◽  
Pitfall Traps ◽  
Element Analysis ◽  
Slope Condition ◽  
Antlion Larvae

Sandy pitfall traps of antlions are elaborate constructions to capture prey. Antlions exploit the interactions between the particles in their habitat and build a stable trap. This trap is close to the unstable state; prey items will slide towards the centre—where the antlion ambushes—when entering the trap. This is efficient but requires permanent maintenance. According to the present knowledge, antlions throw sand, mainly to cause sandslides towards the centre of the pit. We hypothesized that: (i) sand-throwing causes sandslides towards the centre of the pit and (ii) sand-throwing constantly maintains the pitfall trap and thus keeps its efficiency high. Using laboratory experiments, as well as finite-element analysis, we tested these hypotheses. We show, experimentally and numerically, that sand that accumulates at the centre of the pit will be removed continuously by sand-throwing, this maintenance is leading to slope condition close to an unstable state. This keeps the slope angle steep and the efficiency of the trap constant. Furthermore, the resulting sandslides can relocate the trapped prey towards the centre of the pit. This study adds further insights from specific mechanical properties of a granular medium into the behavioural context of hunting antlion larvae.

Effect of pitfall trap depth on epigaeic beetle sampling (Coleoptera: Carabidae and Staphylinidae) in wet forested ecosites in Alberta, Canada

2018 ◽  
Vol 150 (6) ◽  
pp. 813-820
Author(s):  
H.E. James Hammond ◽  
David W. Langor ◽  
Dustin J. Hartley
Keyword(s):  
Species Diversity ◽  
Trap Depth ◽  
Soil Surface ◽  
Organic Soil ◽  
Pitfall Trap ◽  
Pitfall Traps ◽  
Forest Stands ◽  
Soil Layers ◽  
Deep Traps

AbstractThe depth at which pitfall traps were sunk into the ground and the resulting catches of epigaeic Carabidae (Coleoptera) and Staphylinidae (Coleoptera) assemblages in subhygric to hydric ecosites with very deep organic soil layers was investigated in the upper foothills ecoregion of Alberta, Canada. Traps were installed at seven sites, with six surface traps (the pitfall trap lip <5 cm below soil surface) and six deep traps (the pitfall trap lip >20 cm below soil surface) at each site. A total of 5289 beetles representing 75 taxa were collected. There were no significant effects of trap depth on catch. Rarefaction estimates of species diversity were higher in surface pitfall traps for both taxa. The similarity of pooled catches between deep and surface traps was on average 75%, suggesting that both trap types were collecting similar faunas. We found no advantage to using deep pitfall traps in addition to surface traps to sample the epigaeic fauna of wet forest stands and peatlands.

Bionic research on spikes based on the tractive characteristics of ostrich foot toenail

SIMULATION ◽  
2020 ◽  
Vol 96 (9) ◽  
pp. 713-723
Author(s):  
Rui Zhang ◽  
Dianlei Han ◽  
Guolong Yu ◽  
Haitao Wang ◽  
Haibao Liu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Experimental Verification ◽  
Athletic Performance ◽  
Slope Angle ◽  
Element Analysis ◽  
Single Structure ◽  
Athletic Shoes ◽  
Mechanical Information

Inspired by the superior fixed and traction characteristics of ostrich foot toenails, we devised, optimized and manufactured the single structure and group arrangement of a new-style bionic spike for sprint shoes to improve athletic performance. The tractive performance of the bionic spike was tested by finite element analysis and experimental verification. The optimized single structure of the bionic spike had a top slope angle of 13° and the radius of the medial groove of 7.3 mm. Compared with the conventional conic spike, the maximal and stable extrusion resistances of the single bionic spike decreased by about 25% and 40% respectively, while the maximal and stable horizontal thrusts increased by about 16% and 10%, respectively. In addition, the arrangement of the bionic spikes was also optimized. Compared with the conventional spike group, the maximal and stable extrusion resistances of the bionic spike group decreased by 11.0% and 6.2%, respectively, while the maximal and stable horizontal thrusts increased by 20.0% and 16.0%, respectively. The current results may provide useful mechanical information that can help develop a better design of athletic shoes with the potential for advanced performance.

Investigation of Residual Stress Development During Swage Autofrettage, Using Finite Element Analysis

2009 ◽  
Author(s):  
Michael C. Gibson ◽  
Amer Hameed ◽  
John G. Hetherington
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Axial Stress ◽  
Slope Angle ◽  
Subsequent Development ◽  
Element Model ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Reverse Yielding

Swaging is one method of autofrettage, a means of pre-stressing high-pressure vessels to increase their fatigue lives and load bearing capacity. Swaging achieves the required deformation through physical interference between an oversized mandrel and the bore diameter of the tube, as it is pushed through the tube. A Finite Element model of the swaging process was developed, in ANSYS, and systematically refined, to investigate the mechanism of deformation and subsequent development of residual stresses. A parametric study was undertaken, of various properties such as mandrel slope angle, parallel section length and friction coefficient. It is observed that the axial stress plays a crucial role in the determination of the residual hoop stress and reverse yielding. The model, and results obtained from it, provides a means of understanding the swaging process and how it responds to different parameters. This understanding, coupled with future improvements to the model, potentially allows the swaging process to be refined, in terms of residual stresses development and mandrel driving force.

scholarly journals Peranan Semut di Ekosistem Transformasi Hutan Hujan Tropis Dataran Rendah

2020 ◽  
Vol 14 (1) ◽  
pp. 16
Author(s):  
Noor Farikhah Haneda ◽  
Nisfi Yuniar
Keyword(s):  
Tropical Rainforest ◽  
Secondary Forest ◽  
Pitfall Trap ◽  
Rubber Plantation ◽  
Pitfall Traps ◽  
Army Ants ◽  
Purposive Sampling ◽  
Jungle Rubber ◽  
Sampling Plot

Deforestasi atau perubahan fungsi dari hutan menjadi non-hutan berperan dalam perubahan ekosistem dan spesies di dalamnya. Serangga sebagai salah satu fauna di dalamnya merupakan aspek yang menarik untuk dikaji khususnya semut. Tujuan penelitian ini adalah mengidentifikasi peranan-peranan dari genus semut yang ditemukan di ekosistem transformasi. Penelitian dilaksanakan di Desa Bungku, Kecamatan Bajubang, Kabupaten Batanghari, Provinsi Jambi. Metode yang digunakan dalam penelitian ini adalah membuat plot pengamatan secara purposive sampling. Plot pengamatan dipasang di empat eksosistem hutan dengan jumlah masing - masing ekosistem sebanyak empat plot. Setiap plot memiliki lima sub plot yang tersebar di empat eksosistem hutan untuk pemasangan pitfall trap. Teknik pengambilan sampel semut menggunakan pitfall trap di empat ekosistem. Empat ekosistem tersebut yaitu hutan sekunder, perkebunan kelapa sawit, kebun karet, dan hutan karet. Hasil penelitian ditemukan sebanyak 33 genus dari 6 subfamili. Selanjutnya dari 33 genus dikelompokkan berdasarkan peranannya. Berdasarkan peranannya terdapat 46% pencari makan , 36% predator, 3% semut tentara, 3% pemakan bangkai, dan 3% lainnya (semut pemanen/pemetik, omnivora, predator, dan pemakan bangkai). Camponotus sebagai genus dominan memiliki peranan pencari makan, dan Pheidole mempunyai peranan sebagai penghancur biji dan sebagian lainnya adalah omnivora. The Role of Ants in Lowland Tropical Rainforest TransformationAbstractDeforestation or changes functions from forest to non-forest play a role in changing ecosystems and the species within them. Insect as one of the fauna is an interesting aspect to study, especially ants. Aims of this study is to identify the roles of the genus of ants that found in the transformation ecosystem. This study was conducted in Bungku Village, Bajubang District, Batanghari Regency, Jambi. Method used in this study is to make a plot of observation by purposive sampling. Ant sampling techniques use pitfall traps in four ecosystems i.e.. secondary forest, oil palm plantation,rubber plantation, and jungle rubber. This study found 33 genera from 6 subfamilies. Furthermore, 33 genera are grouped based on their roles, i.e. (1) 46% foragers, (2) 36% for predators, (3) 3% for army ants, (4) 3% for scavengers, and (5) 3% for others (harvesting ants, omnivores, predators and scavengers too). Camponotus as the dominant genus has a role for foragers, and Pheidole has a role as a seed destroyer and the other part is omnivorous.

scholarly journals Which Pitfall Traps and Sampling Effort to Choose to Evaluate Cropping System Effects on Spider and Carabid Assemblages?

2020 ◽  
Author(s):  
Antoine Gardarin ◽  
Muriel Valantin-Morison
Keyword(s):  
Body Size ◽  
Habitat Management ◽  
Cropping Systems ◽  
Cropping System ◽  
Pitfall Trap ◽  
Sampling Effort ◽  
Pitfall Traps ◽  
Arthropod Communities ◽  
Trap Design ◽  
Activity Density

Abstract In arable agroecosystems, arthropod communities often have a reduced abundance and diversity, which represents a challenge for sampling techniques needed to detect small differences among these simplified communities. We evaluated the suitability of pitfall traps for comparing the effects of cropping systems on arthropod communities. In a field experiment, we compared the effects of two pitfall trap diameters, the type of preserving fluid and the sampling effort on three metrics (activity density, taxonomic richness, and community weighted mean [CWM] of body size) for carabids and spiders. Trap size affected the observed composition of communities, with large traps yielding a higher proportion of spiders, and a higher richness and CWM body size for both taxa. The type of preserving fluid had a weaker effect. Simulations with various sampling efforts showed that only very different communities could be distinguished with less than 10 traps per field or less than 30 field replicates. Fewer traps were required to find differences between cropping systems for body size than for other metrics. Carabid activity density and body size, and spider genus richness, were the variables better distinguishing between cropping systems with the smallest sampling effort. A high sampling effort was required for comparing activity density and richness across cropping systems. Selection of the most appropriate trap design, metrics, and crops are the main factors for optimizing the trade-off between sampling effort and the ability to detect arthropod community responses to habitat management.

Batch extraction of morphological and color metrics from invertebrate samples. v1

2021 ◽  
Author(s):  
Michael D Weiser ◽  
Katie E. Marshall ◽  
Cameron D. Siler ◽  
Michael Kaspari
Keyword(s):  
Machine Learning ◽  
North America ◽  
Pitfall Trap ◽  
Ground Beetles ◽  
Pitfall Traps ◽  
Batch Extraction ◽  
Continental Scale ◽  
Color Data ◽  
By Catch

This protocol is the complete methods used to extract abundance, morphology and color data from samples of invertebrates. We developed this protocol specifically to measure invertebrate by-catch from pitfall traps collected by the National Ecological Observatory Network (NEON), but these methods could be extended to any invertebrate samples. These methods were used in the publications: Blair, J.,M.D. Weiser, M. Kaspari, M.J. Miller, C. Siler and K. Marshall. 2020. Robust and simplified machine learning identification of pitfall trap-collected ground beetles at the continental scale. Ecology and Evolution 10(23): 13143-13153. DOI:10.1002/ece3.6905. Weiser, M.D., K.E. Marshall, M.J. Miller, C.D. Siler, S.N. Smith & M. Kaspari. in review at Oikos (October 2021). Robust metagenomic evidence that local assemblage richness increases with latitude in ground-active invertebrates of North America.

scholarly journals Solutions and Discussions of thin film Undergoing the Nonlinear Peeling

2003 ◽  
Vol 795 ◽  
Author(s):  
Yueguang Wei ◽  
Siqi Shu ◽  
Ying Du LNM
Keyword(s):  
Thin Film ◽  
Fracture Toughness ◽  
Effective Strain ◽  
Slope Angle ◽  
Interfacial Crack ◽  
Crack Tip ◽  
Interfacial Fracture ◽  
Interfacial Fracture Toughness ◽  
Element Analysis ◽  
Von Mises

ABSTRACTBased on the bending model, three double-parameter criteria characterizing thin film peeling process are introduced and analyzed in detail. Three double-parameter criteria include: (1) the interfacial fracture toughness and the separation strength, (2) the interfacial fracture toughness and the interfacial crack tip slope angle of thin film, and (3) the interfacial fracture toughness and the critical von Mises effective strain of thin film at crack tip. Based on the three double-parameter criteria, the thin film nonlinear peeling problems are solved analytically for each case. The results show that the solutions of thin film nonlinear peeling based on the bending model are very sensitive to the model parameter selections. Through analyses and comparisons for different solutions, a connection between solutions based on the bending models and based on the two-dimensional elastic-plastic finite element analysis is obtained.

Influence of shade covers on pitfall trap temperatures and capture success of reptiles and small mammals in arid Australia

1999 ◽  
Vol 26 (3) ◽  
pp. 341 ◽  
Author(s):  
Trevor J. Hobbs ◽  
Craig D. James
Keyword(s):  
Heat Stress ◽  
Solar Radiation ◽  
Small Mammals ◽  
Pitfall Trap ◽  
Pitfall Traps ◽  
Capture Success ◽  
Arid Landscapes ◽  
Cover Design ◽  
Related Mortality ◽  
Trap Mortality

Shade covers for pitfall traps can be used to reduce the amount of solar radiation penetrating to the bottom of pitfall buckets, thereby reducing the number of captured animals dying from heat-stress. We tested the effectiveness of a variety of shade covers for reducing temperatures in pitfalls and trap mortality of small vertebrates, and examined the effect of one cover design on trap success in arid landscapes. Shade covers made of insulation foil were found to reduce core pitfall temperatures by 20–22˚C compared with uncovered buckets, which reached temperatures greater than 66ºC. Other cover types tested (plastic lid or cardboard) were found to be less effective: core bucket temperatures still reached 48–53ºC. While foil covers do reduce temperatures and therefore the probability of heat-stress-related mortality, above-ground foil covers also influence trap success. Traps with above-ground foil covers caught 39–43% fewer small vertebrates and 7–42% fewer species than uncovered traps. Above-ground foil covers had the greatest influence on the sampled abundance of scincid lizards (reduced by 50–52%), reduced the sampled abundance of most other lizard families and mammals, but increased capture success for snakes. If shade covers are required to minimise heat stress and mortality in pitfall buckets we recommend foil covers placed inside the bottom pitfall buckets as they significantly reduce pitfall temperatures and are likely to have minimal influence on trap success. However, regular checking of traps is still one of the most reliable ways to reduce heat-stress- related and other deaths in pitfall traps.

Changes in the recovery of insects in pitfall traps associated with the age of cow dung bait fresh or frozen at the time of placement

2020 ◽  
pp. 1-8
Author(s):  
G.A. Bezanson ◽  
C.D. Dovell ◽  
K.D. Floate
Keyword(s):  
Pitfall Trap ◽  
Cattle Dung ◽  
Cow Dung ◽  
Pitfall Traps ◽  
Short Term ◽  
Confounding Effect ◽  
Weather Events ◽  
Southern Alberta ◽  
Two Factors ◽  
Trap Experiment

Abstract Pitfall traps baited with cattle dung are commonly used to characterize local assemblages of coprophilous insects. Baits can be made fresh or be prepared in advance and kept frozen until needed. Insect recoveries are expected to decline with the age of the bait and may be affected by the use of fresh vs. frozen baits. To assess the effect of these two factors on insect recoveries, we performed a pitfall trap experiment that was repeated in four trials spanning 2 years and two locations in southern Alberta, Canada. The experimental design allowed us to minimize the potential confounding effect of short-term weather events. For results combined across trials, baits aged >3 days were largely ineffective for attracting coprophilous species. Frozen baits attracted significantly more insects than did fresh dung for the first 3 days after placement in the field with no difference thereafter. Our findings suggest that insect recoveries in dung-baited pitfall traps can be maximized with the use of frozen baits with replacement every 3–4 days.

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