Arena Size Research Articles

Foraging Arena Size and Structural Complexity Affect the Dynamics of Food Distribution in Ant Colonies

Food acquisition by ant colonies is a complex process that starts with acquiring food at the source (i.e., foraging) and culminates with food exchange in or around the nest (i.e., feeding). While ant foraging behavior is relatively well understood, the process of food distribution has received little attention, largely because of the lack of methodology that allows for accurate monitoring of food flow. In this study, we used the odorous house ant, Tapinoma sessile (Say) to investigate the effect of foraging arena size and structural complexity on the rate and the extent of spread of liquid carbohydrate food (sucrose solution) throughout a colony. To track the movement of food, we used protein marking and double-antibody sandwich enzyme-linked immunosorbent assay, DAS-ELISA. Variation in arena size, in conjunction with different colony sizes, allowed us to test the effect of different worker densities on food distribution. Results demonstrate that both arena size and colony size have a significant effect on the spread of the food and the number of workers receiving food decreased as arena size and colony size increased. When colony size was kept constant and arena size increased, the percentage of workers testing positive for the marker decreased, most likely because of fewer trophallactic interactions resulting from lower worker density. When arena size was kept constant and colony size increased, the percentage of workers testing positive decreased. Nonrandom (clustered) worker dispersion and a limited supply of food may have contributed to this result. Overall, results suggest that food distribution is more complete is smaller colonies regardless of the size of the foraging arena and that colony size, rather than worker density, is the primary factor affecting food distribution. The structural complexity of foraging arenas ranged from simple, two-dimensional space (empty arenas) to complex, three-dimensional space (arenas filled with mulch). The structural complexity of foraging arenas had a significant effect on food distribution and the presence of substrate significantly inhibited the spread of food. Structural complexity of foraging arenas and the resulting worker activity patterns might exert considerable influence on socioecological processes in ants and should be considered in laboratory assays.

Size and spacing of grouse leks: comparing capercaillie (Tetrao urogallus) and black grouse (Tetrao tetrix) in two contrasting Eurasian boreal forest landscapes

Capercaillie ( Tetrao urogallus L., 1758) and black grouse ( Tetrao tetrix L., 1758 (= Lyrurus tetrix (L., 1758))) are two sympatric Eurasian lekking grouse species that differ markedly in habitat affinities and social organization. We examined how size and spacing of leks in pristine (Russia) and managed (Norway) forests were related to habitat and social behavior. Leks of both species were larger and spaced farther apart in the pristine landscape. Capercaillie leks were regularly spaced at 2–3 km distance, increasing with lek size, which in turn was positively related to the amount of middle-aged and older forests in the surrounding area. Black grouse leks were irregularly distributed at shorter distances of 1–2 km, with lek size explained by the size of the open bog arena and the amount of open habitat in the surroundings. At the landscape scale, spatial distribution of open bogs and social attraction among male black grouse caused leks to be more aggregated, whereas mutual avoidance in male capercaillie caused leks to be spaced out. In the pristine landscape, large-scale and long-term changes in forest dynamics owing to wildfires, combined with an aggregated pattern of huge bog complexes, presumably provide both grouse species with enough time and space to build up bigger lek populations than in the managed landscape.

Spatial reorientation in rats ( Rattus norvegicus): Use of geometric and featural information as a function of arena size and feature location

Rats were used in a spatial reorientation task to assess their ability to use geometric and non-geometric, featural, information. Experimental conditions differed in the size of the arena (small, medium, or large) and whether the food-baited corner was near or far from a visual feature. The main measure was the percentage of trials with first-choice visits to the baited corner (Corner C) and the geometric equivalent corner (Corner R). Regardless of arena size, only the rats in the near-feature condition learned to make more first-choice visits to Corner C than Corner R. However, in this condition, there was a significant trend suggesting an increasing and decreasing use of, respectively, featural and geometric information with increasing arena size. Continued training with the feature removed caused all rats to primarily visit Corners C and R, reflecting the exclusive use of geometric information. However, again, there was a significant trend suggesting a decreasing use of this type of information with increasing arena size. These results were discussed in the framework of data from previous studies assessing reorientation in other species and of an associative-learning model.

Effects of (−)-OSU6162 and ACR16 on motor activity in rats, indicating a unique mechanism of dopaminergic stabilization

Dopaminergic stabilizers can be defined as drugs that stimulate or inhibit dopaminergic signalling depending on the dopaminergic tone. (-)-OSU6162 and ACR16 appear to possess such a profile. They have been proposed to act as partial dopamine receptor agonists or as antagonists with preferential action on dopaminergic autoreceptors. Previous studies have shown either stimulation or inhibition of behaviour in response to (-)-OSU6162 and ACR16, which has been suggested to reflect their dual effects on dopaminergic signalling. The aims of the present work are to (1) examine the relation between behavioural response to these drugs and activity baseline, and (2) test the suggested mechanisms of action by means of close comparisons with the known partial D2-receptor agonists (-)-3-PPP and aripiprazole, and the D2 autoreceptor preferring antagonist amisulpride with respect to effects on behaviour. From the results of these experiments it can be concluded that: (1) The direction of the response to (-)-OSU6162 and ACR16 is dependent on activity baseline, which in turn, under physiological conditions, is determined primarily by test arena size of and degree of habituation to the environment. (2) The effects of (-)-OSU6162 and ACR16 cannot be explained on the basis of either partial dopamine receptor agonism or preferential dopamine autoreceptor antagonism. Nevertheless, the current data suggest at least two different D2-receptor-associated targets which mediate opposite effects on activity. This result fits in with a mechanism proposed from a recent in vitro study, according to which (-)-OSU6162 has a dual action on dopamine D2 receptors, (a) an allosteric effect causing an enhanced response to dopamine, and (b) the previously proposed orthosteric effect antagonizing the action of dopamine.

Predator–prey interactions between crayfish (Orconectes juvenilis) and snails (Physa gyrina) are affected by spatial scale and chemical cues

Abstract. We conducted two experiments to compare the behaviors of predatory crayfish (Orconectes juvenilis) and snail prey (Physa gyrina), with and without exposure to injured‐snail cues, in seven different sizes of arena. Individuals in both O. juvenilis and P. gyrina are known to obtain information about predation events from chemical cues present in the water, but the effect of spatial scale on this information or the ensuing interaction has not been previously investigated. We found that crayfish were generally more active in larger arenas, but their response to injured‐snail cues decreased as arena size increased. Snails responded to injured‐snail cue by seeking refuge, but responded less strongly in larger arenas. Less time was required for crayfish to capture a snail in the presence of injured‐snail cue, and there was an interaction between cue and arena size evident in middle‐sized arenas. Consumption time was lower in the presence of injured‐snail cue but was unaffected by arena size. Based on these results, we conclude that the effects of injured‐snail cue are mediated by spatial scale, and this affects the outcome of this predator–prey interaction. Spatial scale should be considered in the design and interpretation of other predator–prey studies, particularly when sensory or motility differences exist between predators and prey that affect how each gathers information about the environment.

Functional response: rigorous estimation and sensitivity to genetic variation in prey

Holling's type II functional response is a cornerstone of community ecology and coevolutionary theory. The so‐called disc equation is the most widely used model of the type II response, yet thus far no robust experimental assessment has been achieved in any single system. Fundamental issues that remain to be assessed include whether the assumptions of the disc equation are fulfilled, whether the disc equation yields accurate estimates of predation‐related individual traits, and whether differences in disc equation parameters can capture genetic variation in prey behaviour. This paper provides a rigorous approach to all of these questions. The functional response of the predatory mitePergamasus crassipeson three genetically distinct clones of the springtailFolsomia candidawas measured at six levels of prey density in controlled conditions where prey number and arena size were concomitantly manipulated. A crucial assumption of Holling's disc equation was fulfilled by maintaining a constant prey density for the entire experimental period of predation. The timing of each attack and capture, as well as the duration of the handling time, were recorded by constant observation. We contrasted three different methods to calculate functional response curves: (1) indirect estimation of the disc equation's parameters from the number of prey killed by the end of each experimental run; (2) direct estimation of the parameters via a unique protocol of constant observation; and (3) independently deriving a function based on direct measurements of encounter rate and attack success. The basic assumptions of the disk equation were globally fulfilled. Estimations of the functional response's parameters (type II) were remarkably congruent across approach (1) and (2). A single genetic effect was detected – the relationship between the encounter rate and prey density differed significantly between clones – whereas a direct comparison of functional response across clones failed to reveal genetic variation.

Texture of locomotor path: a replicable characterization of a complex behavioral phenotype

A database of mouse locomotor path in spatial tests can be used to search in silico for behavioral measures that better discriminate between genotypes and are more replicable across laboratories. In this study, software for the exploration of exploration (SEE) was used to search a large database for a novel behavioral measure that would characterize complex movement paths. The database included mouse open-field behavior assessed in 3 laboratories, 7 inbred strains, several pharmacological treatments and hundreds of animals. The new behavioral measure, "path texture", was characterized using the local curvature of the path (the change of direction per unit distance, in degrees/cm) across several spatial scales, starting from scales smaller than the animal's body length and up to the scale of the arena size. Path texture analysis differs from fractal dimension analysis in that it does not assume self-similarity across scales. Path texture was found to discriminate inbred strains with relatively high broad-sense heritability (43%-71%) and high replicability across laboratories. Even genotypes that had similar path curvatures in some scales usually differed in other scales, and self-similarity across scales was not displayed by all genotypes. Amphetamine decreased the path curvature of C57BL/6 mice in small and medium scales, while having no effect on DBA/2J mice. Diazepam dose-dependently decreased the curvature of C57BL/6 mice across all scales, while 2 anxiogenic drugs, FG-7142 and pentylenetetrazole, increased it. Path texture thus has high potential for behavioral phenotyping and the study of drug effects in the mouse.

Spatial scale, heterogeneity and functional responses

Summary In a laboratory experiment, we studied the effect of arena size on the functional response of the mysid shrimp Neomysis integer preying on the cladoceran Polyphemus pediculus. The aim of the study was to examine mechanisms that cause the functional response to be scale‐dependent, by documenting the spatial distribution and the movement behaviour of predator and prey. The attack rate was significantly higher in large arenas, while the handling time did not differ between arena sizes. The difference in attack rate could be explained by differences in aggregative behaviour of predator and prey and in swimming activity of the predator. It is suggested that distributions of animals are often affected by the walls of the experimental arenas and that this spatial heterogeneity is scale‐dependent, which may have a considerable impact on estimates of ecological process rates. A method of correcting attack rate estimates for artefacts caused by such spatial heterogeneity is presented.

Arena size, hole density, and capture of Oryzaephilus surinamensis (Coleoptera: Silvanidae) in grain probe traps.

The relationship of size of test arena, number of holes in a grain probe trap body and capture of the sawtoothed grain beetle, Oryzaephilus surinamensis (L.), was determined in simulated field tests conducted in an outdoor screen enclosure exposed to natural temperature fluctuations. Polyvinylchloride (PVC) probe bodies were attached to electronic sensor heads, and insect captures were recorded electronically using an electronic grain probe insect counter (EGPIC) system. In comparisons among PVC probe trap bodies with 60, 132, 252, and 492 holes, tested at 18 insects per kilogram in 4.5, 17, and 40 kg of soft wheat in cylindrical arenas (10.2, 20.3, and 30.5 cm in diameter, respectively), number of holes in the probe trap body had no effect on insect capture, but percentage of insects recovered was indirectly related to size of the test arena. Periodicity of insect capture was determined using the time-stamp data that were recorded by the EGPIC system. Circadian rhythm was observed in the periodicity of the capture that corresponded to foraging activity peaks documented for sawtoothed grain beetles, with activity peaks occurring early in the scotophase. There were shifts in times of peak activity among the different test arena sizes that corresponded to differences in temperature in the grain mass. Increases in both temperature and contact between insects and grain probe in the smallest arenas resulted in higher capture of sawtoothed grain beetles. This research documents additional important factors when evaluating capture of sawtoothed grain beetles in grain probe traps.

Food distance and its effect on nutrient balancing in a mobile insect herbivore

We investigated how the distance between foods of differing nutrient content affects macronutrient (protein and digestible carbohydrate) regulation and the patterns of food acquisition, movement and feeding activity in fifth-instar nymphs of Locusta migratoria (L.) (Orthoptera: Acrididae). We placed individual insects into one of three differently sized circular arenas (20, 40 or 80 cm diameter) that contained four dishes of chemically defined synthetic food. One of these dishes contained high-protein, low-carbohydrate food (P), and the other three dishes contained low-protein, high-carbohydrate food (C). Alone, these foods are nutritionally unbalanced, but together they are complementary. Regardless of arena size, locusts regulated their protein–carbohydrate intake to similar points, and in all three arenas they ate preferentially from the dish containing the P-food. We also recorded the patterns of foraging behaviour for 12 h on days 1 and 4 of the experiment, which allowed us to determine the effect of distance between foods and whether behaviour was modified with experience in the different arenas. Locusts' foraging behaviour in small arenas was similar on days 1 and 4, and the time they spent in different parts of the arena did not differ from that predicted by the simplest random probability model. In contrast, the foraging behaviour of locusts in the medium and large arenas changed between days 1 and 4, including spending more time in the area of the arena containing the P-food and visiting fewer of the C-food dishes. We discuss how distance between foods influences foraging strategies, and the possible role of learning in its development. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.

Parasitoid Density and Arena Size Effects on Progeny Production of Anaphes iole Girault (Hymenoptera: Mymaridae)

Anaphes iole Girault is a native, solitary egg parasitoid of Lygus bugs in North America. Ongoing research is considering factors that may lead to efficient mass rearing of A. iole for augmentative biological control. This study examined the effects of A. iole female density and arena size on progeny production. Production increased by a factor of 2.1 as parasitoid density increased from 5 to 10 and from 10 to 20 females per 8 Larena (rearing cage) with a host patch containing from 1,500 to 2,000 eggs of Lygus hesperus Knight (Heteroptera: Miridae). Sex ratios of mature progeny did not differ significantly between parasitoid densities of 10 versus 20 females. Arena size (≈1, 2, 4, or 8 L cages) had no effect on progeny production when 20 females were confined to the same cage. This research suggests that little or no measurable interference will occur between ovipositing A. iole females on shared host patches and cage size can be varied to increase rearing capacity.

Open-field behavior withstands drastic changes in arena size

Individual voles were tested on successive days under increasing, decreasing, or randomly changing arena size. Locomotor behavior was adjusted to arena size by (i) preserving the same level of activity, (ii) taking longer but less frequent trips in smaller arenas in contrast to taking more frequent yet shorter trips in the larger arenas, and (iii) moving in the entire space available for exploration in the smaller arenas in contrast to remaining along the walls of the open field in the larger arenas. The effect of testing order was minimal, probably being related to increased novelty under increasing arena size, as opposed to habituation under decreasing arena size, when parts of the same area were re-explored. These behavioral changes averaged up to a two-fold difference compared with the larger six-fold change in the perimeter and 44-fold change in the area of the open field. The modest change in open-field behavior indicates that it has a solid spatio-temporal structure that withstands extensive environmental changes. This behavioral stability and consistency further validates studies of pharmacological, neurological, and genetic preparations that use behavior in a small open field as representation of the general pattern of behavior.

Ratio‐dependent parasitism with Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae) on egg rafts of Nezara viridula (Linnaeus) (Hemiptera: Pentatomidae): effect of experimental variables and compatibility of ‘ratio’ and ‘Holling’ models

Abstract Egg rafts of Nezara viridula were exposed to the parasitoid wasp Trissolcus basalis in experimental arenas to establish the relationship of the rates of attack and parasitism to various combinations of arena size, parasitoid density, host density and parasitoid‐to‐host ratio. Arena sizes were varied in the ratio 1:9:63, with the largest having a search area of 1.44 m2. Parasitoid and host densities were varied over a 27‐fold range. The parasitoid‐to‐host ratios used were 1:1, 3:1 and 6:1. Finding time was related to a constant factor (flight propensity), rather than to the difficulty of finding (density of hosts). Initial attack rates were therefore related only to parasitoid numbers (or density), even at the lower densities and ratios. Parasitism rates (a function of attack rate per host) were thus also strongly related to parasitoid to host ratio, regardless of densities used and arena sizes. Even reducing host density, while keeping time and parasitoid density constant, increased the parasitism rate. A ratio model for parasitism rate was therefore compatible with the data but the more explicit Holling ‘disc’ equation was also compatible because handling time was sufficiently large to make it sensitive to the ratio of parasitoids to hosts for the densities used. We conclude that the two models would predict different results if the density of host egg rafts was in a range below one per square metre.

Estimating predation rates in experimental systems: scale‐dependent effects of aggregative behaviour

We studied the effect of arena size on estimates of prey mortality rate in predation experiments. In a laboratory experiment involving two of the dominating benthic species in the northern Baltic Sea, the predacious isopodSaduria entomon, and its main prey, the amphipodMonoporeia affinis, the prey mortality rate increased with container radius. The densities of both predator and prey close to the wall increased with container size. We hypothesised that this scale‐dependent coaggregation of predator and prey caused the mortality rates to increase with arena size. We tested the hypothesis with the help of a simple model, by calculating the expected number of prey eaten in containers of different size from experimental data on the distributions of predator and prey within the arenas. A significant relationship between expected and observed numbers eaten supported our hypothesis. As the aggregative response was most pronounced in large arenas, this leads to the counterintuitive conclusion that large containers produced more biased estimates of morality rates than small containers. To further study the effects of coaggregation we explored a general simulation model where both predator and prey preferred the habitat close to the arena wall. The model predicted a humpshaped relationship between encounter rate and arena size. This suggests that when predators and prey show a scale‐dependent tendency to aggregate along arena walls, the most accurate estimates of predation rates may be obtained with very small or very large arenas.

Natural segmentation of the locomotor behavior of drug-induced rats in a photobeam cage

Recently, Drai et al. (J Neurosci Methods 96 (2000) 119) have introduced an algorithm that segments rodent locomotor behavior into natural units of ‘staying in place’ (lingering) behavior versus going between places (progression segments). This categorization, based on the maximum speed attained within the segment, was shown to be intrinsic to the data, using the statistical method of Gaussian Mixture Model. These results were obtained in normal rats and mice using very large (650 or 320 cm) circular arenas and a video tracking system. In the present study, we reproduce these results with amphetamine, phencyclidine and saline injected rats, using data measured by a standard photobeam tracking system in square 45 cm cages. An intrinsic distinction between two or three ‘gears’ could be shown in all animals. The spatial distribution of these gears indicates that, as in the large arena behavior, they correspond to the difference between ‘staying in place’ behavior and ‘going between places’. The robustness of this segmentation over arena size, different measurement system and dose of two psychostimulant drugs indicates that this is an intrinsic, natural segmentation of rodent locomotor behavior. Analysis of photobeam data that is based on this segmentation has thus a potential use in psychopharmacology research.

The EthoVision video tracking system—A tool for behavioral phenotyping of transgenic mice

Video tracking systems enable behavior to be studied in a reliable and consistent way, and over longer time periods than if they are manually recorded. The system takes an analog video signal, digitizes each frame, and analyses the resultant pixels to determine the location of the tracked animals (as well as other data). Calculations are performed on a series of frames to derive a set of quantitative descriptors of the animal's movement. EthoVision (from Noldus Information Technology) is a specific example of such a system, and its functionality that is particularly relevant to transgenic mice studies is described. Key practical aspects of using the EthoVision system are also outlined, including tips about lighting, marking animals, the arena size, and sample rate. Four case studies are presented, illustrating various aspects of the system: (1) The effects of disabling the Munc 18-1 gene were clearly shown using the straightforward measure of how long the mice took to enter a zone in an open field. (2) Differences in exploratory behavior between short and long attack latency mice strains were quantified by measuring the time spent in inner and outer zones of an open field. (3) Mice with hypomorphic CREB alleles were shown to perform less well in a water maze, but this was only clear when a range of different variables were calculated from their tracks. (4) Mice with the trkB receptor knocked out in the forebrain also performed poorly in a water maze, and it was immediately apparent from examining plots of the tracks that this was due to thigmotaxis. Some of the latest technological developments and possible future directions for video tracking systems are briefly discussed.

Application of a model of scale dependence to quantify scale domains in open predation experiments

We use a model of open predation experiments to define scale domains that differ in terms of the controlling processes and scale dependence of predator impacts. For experimental arenas that are small compared to the movements of the prey (small scale domain) the model predicts that predator impacts are scale independent and controlled by prey movements. For arenas of intermediate scale we predict that predator impacts are scale dependent and controlled by both prey movements and direct predation, and for the largest scale domain we predict weak scale dependence and predation control. We propose that the scale‐domain concept is useful when designing and interpreting field experiments. As an illustration we apply the concept to experiments examining predator effects on the stream benthos. First, we test two key assumptions of the underlying model: that area‐specific prey migration rates decrease with increasing size of experimental arenas and that predation rates are independent of arena size. For this purpose we used published estimates of prey emigration and predator consumption rates for nine studies examining the effects of stream predators on benthic prey. We found that prey per capita emigration rates but not predation rates decreased with increasing arena length. Second, we demonstrate a method for identifying the scale domain of real experiments. The model of predation experiments was parameterized using experimental data and the expected spatial and temporal scale dependence of predator impacts on prey in these experiments was simulated. The simulations suggest that the studies conducted in the largest arenas (length 15–35 m) should be classified as large‐scale, consumption‐controlled experiments, whereas the experiments conducted in smaller arenas (length 1.5–6 m) should be classified as small or intermediate‐scale. We also attempted to determine the scale domain of the experiments in a large data set, including results from most published stream predation experiments. The majority of arenas used in these experiments (73%) were smaller than 1 m in length. Our data on the scale dependence of predation and prey migration rate suggest that experiments in this scale range (<1 m) should be classified as small‐scale, movement‐controlled experiments for most prey taxa.

A Strategy for the Analysis of Idea Innovation Networks and Institutions

The perspective of this paper is that variation in commercially successful radical product/process innovations among science-based industrial sectors can be explored by focusing on idea innovation networks. Idea innovation networks have six arenas reflecting research basic research, applied research, product development research, production research, quality control research, and commercialization/ marketing research. The paper develops two interrelated hypotheses. The first is that the greater the diversity of competencies or knowledges that are connected with frequent and intense communication within an arena and the greater the size of the arena, and the greater the likelihood that radical innovations will emerge. The second hypothesis involves the same kind of logic: if radical solutions are to occur in more than one arena, there must be intense and frequent communication among the different arenas involving radically new ways of thinking. Radical research solutions in one arena usually involve tacit knowledge and to be effectively communicated to another arena, both tacit knowledge and codified knowledge must be communicated across arenas. However, the communication of tacit knowledge is more likely to occur when there is frequent and intense communication across arenas.In analyzing connectedness, the authors draw on the literatures about organizational innovation and organizational learning. In addition, they recognize that institutional environments shape the size of research arenas and the connectedness within and among them. The suggestion is that the more similarity there is across sectors, in patterns of research arena size and connectedness, the greater the support for a national system of innovation interpretation. Contrariwise, less similarity of network arena characteristics across sectors may mean more support for the strong role of globalization forces in affecting innovation.

Effect of Trichilia americana extract on feeding behavior of Asian armyworm, Spodoptera litura.

We investigated the desensitization of Asian armyworms, Spodoptera litura, to a crude methanolic extract of wood Trichilia americana. Following repeated exposures to the extract over four days, desensitization was observed under no-choice conditions at low extract concentration (0.5 μg/cm2). No desensitization was observed under choice conditions or at a higher concentration (5.0 μg/cm2). Repeated exposures of larvae to the extract over 7.5 hr showed that larvae increasingly tolerated the extract due to hunger, rather than showing true desensitization. When larvae were exposed to the extract in test arenas of different sizes, larvae showed reduced feeding and desensitization as arena size increased. Finally, treatment of whole cabbage plants with extract resulted in larvae abandoning the plant. The crude extract was effective at protecting the plants, although desensitization did not occur, because the larvae moved away from the plant.

Factors Influencing the Infectivity of a Canadian Isolate ofSteinernema kraussei(Nematoda: Steinernematidae) at Low Temperature

The effectiveness of Canadian isolate 76 ofSteinernema kraussei,at 10°C, in penetratingGalleria mellonellalarvae (percentage parasitism and number of IJs developed to adult nematodes) was measured at different host densities (differing number of larvae and size of experimental arena) and for different durations of exposure. The greater the size of the inoculum of infective juvenile nematodes per unit area and the longer the duration of exposure, the greater the number of larvae that were killed and the larger the number of mature nematodes in the larval host. The infection rate (α) and the adjusted infection rate (β) were determined using the modified Anderson model. This model successfully described the behavior of theS. kraussei–G. mellonellainteraction.