Ontogenetic Development of Spatial Orientation in First- and Second-instar Cockroach Larvae (Blattella germanica (L.), Dictyoptera)

Changes in spatial orientation related to aging were investigated during the first two instars in Blattella germanica (L). Spatial orientation was tested through shelter return under various experimental conditions in order to understand how kinesthetic path integration and visual cues intervene in the construction of this behaviour. We were able to distinguish two types of changes: experience during the first instar and maturation between instars. Young larvae need 2–3 d to develop the appropriate shelter-return behaviour when they can only use visual cues. By contrast, they can use kinesthetic path-integration cues efficiently to return to the shelter as soon as they hatch.     

Homing in the Mangrove Swimming Crab Thalamita crenata (Decapoda: Portunidae)

On the Kenyan coast, Thalamita crenata confines itself to a defined system of crevices and forages, swimming in a few cm of water, within a radius of about 5 m from its shelter. A field study was designed to analyse this crab's ability to find its shelter after being moved away from it. Crabs were displaced, being kept under water, with full vision of the sky and landscape and released 5 m away from their refuges, at a maximum depth of 50 cm. They were able to return to their shelters within 1 h and followed initial directions which were well orientated towards home. T. crenata was still well orientated and successful in returning home during nocturnal displacements and even after trials in which the landscape was altered. Only blind crabs were neither initially orientated towards home nor successful in returning within two tidal cycles of their release. The hypothesis that this swimming crab could use orientating information obtained during the outward displacement was then tested. Specimens were dislocated following a non-linear outward path, without vision of the surrounding landscape; other crabs were carried to a false release point and then carried in a closed container to the actual release point. Finally, three kinds of detour experiments were performed. In all these trials the directions chosen by the crabs were still clustered around the home direction and homing success was again high. These results exclude homing mechanisms based on random search strategies or on egocentric mechanisms, such as path integration. The most probable hypothesis is that T. crenata organizes some visual cues in a map-like arrangement and, detecting these cues from any release point within its home range, uses this map to return home.     

Spatial Orientation in Blattella germanica L. Larvae

The aim of these experiments was to investigate the type of cues used in homing processes by young Blattella germanica L. larvae. Several types of stimuli were tested: path integration with kinesthetic cues and visual orientation with landmark cues. Tests measured the escape direction of larvae from the food box after disturbance. Either type of cue alone, path integration or visual landmarks, was sufficient to allow larvae to orient towards their shelters, but they oriented more precisély when both types of cue were used. When several landmark cues (proximal and distal) were present, their relative angular position seemed important in the orientation process. Macroscopic shapes in the environment appeared to be used as a global image, memorized to reach the shelter.     

Path integration controls nest-plume following in desert ants

The desert ant Cataglyphis fortis is equipped with sophisticated navigational skills for returning to its nest after foraging. The ant's primary means for long-distance navigation is path integration, which provides a continuous readout of the ant's approximate distance and direction from the nest. The nest is pinpointed with the aid of visual and olfactory landmarks. Similar landmark cues help ants locate familiar food sites. Ants on their outward trip will position themselves so that they can move upwind using odor cues to find food. Here we show that homing ants also move upwind along nest-derived odor plumes to approach their nest. The ants only respond to odor plumes if the state of their path integrator tells them that they are near the nest. This influence of path integration is important because we could experimentally provoke ants to follow odor plumes from a foreign, conspecific nest and enter that nest. We identified CO(2) as one nest-plume component that can by itself induce plume following in homing ants. Taken together, the results suggest that path-integration information enables ants to avoid entering the wrong nest, where they would inevitably be killed by resident ants.     

Influence of caterpillar-feeding damage on the foraging behavior of the paper waspMischocyttarus flavitarsis (Hymenoptera: Vespidae)

Experiments were performed to determine the effect of caterpillar feeding damage on wasp foraging behavior and to determine the relative importance of visual and olfactory plant cues for foraging wasps. In an experiment using caterpillar-damaged leaves, wasps took significantly more larvae from the previously damaged plants compared to the controls in the experiments with tobacco plants, but wasps did not distinguish between damaged and control plants in the experiments with tomato plants. Another experiment indicated that wasps use a combination of visual and olfactory cues of plant damage in their search for prey rather than just visual or olfactory cues alone. Furthermore, these results suggest that leaf shape may affect wasp detection of caterpillar feeding damage and thus detection of prey.     

Use of learned visual cues during habitat location by Brachymeria intermedia

Like many other parasitoids, Brachymeria intermedia (Hymenoptera: Chalcididae) uses olfactory cues to find its host, but in addition it appears to use learned visual cues to focus its searching efforts at the macrohabitat level. In laboratory experiments, females were held in cages where Lymantria dispar pupae were hidden either in a vertical, tree-like structure or on the floor. After four days females had learned to search for hosts in the structure in which they previously had found pupae. Such training was reversible. During similar tests in a semi-natural situation, in which pupae were hung from a tree trunk or were hidden under leaf litter, females also tailored their subsequent searching to favour the macrohabitat where hosts previously had been found. This parasitoid most likely uses a combination of visual and olfactory cues during host searching.     

Microhabitat use affects goby (Gobiidae) cue choice in spatial learning task

This study investigated whether spatial learning ability and cue use of gobies (Gobiidae) from two contrasting habitats differed in a spatial task. Gobies were collected from the spatially complex rock pools and dynamic, homogenous sandy shores. Fishes were trained to locate a shelter under the simulated threat of predation and it was determined whether they used local or extra‐maze (global) and geometric cues to do so. It was hypothesized that fishes from rock pools would outperform fishes from sandy shores in their ability to relocate shelter and the two groups would differ in their cue use. It was found that rock‐pool species learnt the location of the correct shelter much faster, made fewer errors and used a combination of all available cues to locate the shelter, while sand species relied significantly more on extra‐maze and geometric cues for orientation. The results reported here support the hypothesis that fishes living in complex habitats have enhanced capacity for spatial learning and are more likely to rely on local landmarks as directional cues than fishes living in mundane habitats where local cues such as visual landmarks are unreliable.     

Pollinator attraction in Cornus capitata (Cornaceae): the relative role of visual and olfactory cues

Aims It is generally accepted that visual displays and floral scent play important roles in communication between flowering plants and their pollinators. However, the relative role of visual and olfactory cues in pollinator attraction is largely unknown. In this study, we determined the roles of both types of cue in attracting pollinators to Cornus capitata, a medium sized tree with each capitulum surrounded by four large, white, petaloid bracts.Methods Pollinator observations and pollination experiments were conducted in a natural population; the inflorescences' visual and olfactory signals were characterized by spectral and chemical analyses; the responses of pollinators to visual and olfactory cues were tested using dual-choice behavioural bioassays; the relative roles of visual and olfactory cues in pollinator attraction were tested by comparing the responses of pollinators to inflorescences subjected to three experimental treatments (intact, all bracts removed, and capitulum removed) within the natural population.Important findings For fruit set, C. capitata is entirely dependent on pollinators, with a bee, Anthophora sp., being the main pollinator. Bracts present high colour distance and green contrast against the leaves. Twelve volatile compounds in the floral scent were detected, most of which have previously been reported to be attractive to a broad spectrum of bee species. Behavioural bioassays showed that both, visual cues alone and olfactory cues alone, are attractive to pollinating bees. However, visual cues alone attracted significantly more approaches than olfactory cues alone, while olfactory cues alone elicited a significantly higher landing percentage than visual cues alone. The finding suggests that, in the C. capitata – Anthophora sp. interaction, visual cues are mainly used for location from long distances, while olfactory cues mainly aid landing from short distances. Our results indicate that different modalities of floral cues should be considered together to understand fully the communication between flowering plant and pollinators.     

Round-the-clock homing behavior of a subsocial shield bug, Parastrachia japonensis (Heteroptera: Parastrachiidae), using path integration

Females of the subsocial shield bug, Parastrachia japonensis (Parastrachiidae), are central-place foragers, collecting drupes for their young from nearby host trees by walking along the forest floor both during the day and at night. Because burrows are often some distance from the drupe-shedding tree, the bugs must repeatedly leave their burrows, search for drupes, and return to the burrows. After a bug leaves its burrow, it searches arduously until it encounters a drupe. When a drupe is obtained, the bug always takes the shortest route back to its burrow. It has been clarified that this bug utilizes path integration during diurnal provisioning excursions. In this paper, we examined nocturnal behavior and some parameters of the path integration utilized by P. japonensis. There were no observable differences between day and night in the patterns of foraging and direct-homing behavior. When the bug was displaced to another position during the day or night, it always walked straight toward the fictive burrow, the site where the burrow should be if it had been displaced along with the bug, and then displayed searching behavior in the vicinity of the fictive burrow. The distance of the straight run corresponded accurately with a straight line between the burrow and the place where the bug obtained the drupe. These results indicate that P. japonensis orients toward the burrow using path integration both during diurnal and nocturnal provisioning behavior.     

Integration of Visual and Olfactory Cues in Host Plant Identification by the Asian Longhorned Beetle,Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae)

Some insects use host and mate cues, including odor, color, and shape, to locate and recognize their preferred hosts and mates. Previous research has shown that the Asian longicorn beetle, Anoplophora glabripennis (Motschulsky), uses olfactory cues to locate host plants and differentiate them from non-host plants. However, whether A. glabripennis adults use visual cues or a combination of visual and olfactory cues remains unclear. In this study, we tested the host location and recognition behavior in A. glabripennis, which infests a number of hardwood species and causes considerable economic losses in North America, Europe and Asia. We determined the relative importance of visual and olfactory cues from Acer negundo in host plant location and recognition, as well as in the discrimination of non-host plants (Sabina chinensis and Pinus bungeana), by female and male A. glabripennis. Visual and olfactory cues from the host plants (A. negundo), alone and combined, attracted significantly more females and males than equivalent cues from non-host plants (S. chinensis and P. bungeana). Furthermore, the combination of visual and olfactory cues of host plants attracted more adults than either cue alone, and visual cues alone attracted significantly more adults than olfactory cues alone. This finding suggests that adult A. glabripennis has an innate preference for the visual and/or olfactory cues of its host plants (A. negundo) over those of the non-host plant and visual cues are initially more important than olfactory cues for orientation; furthermore, this finding also suggests that adults integrate visual and olfactory cues to find their host plants. Our results indicate that different modalities of host plant cues should be considered together to understand fully the communication between host plants and Asian longhorned beetles.     

Memory of Location and Site Recognition in the Ant Formica uralensis (Hymenoptera: Formicidae)

Spatial recognition cues used in site fidelity in the ant Formica uralensis Ruzsky were studied using outdoor and laboratory arenas. Ant workers visiting symmetrically spaced feeders were colour-marked corresponding to the initial feeder visited during sampling. The effect of manipulating environmental cues on the mean 'spatial specialization' of the population was measured. Site recognition appears to be based on visual landmark/canopy cues. However, ants maintained some fidelity when shielded from these cues, suggesting the involvement of additional cues. When ridding our experimental device of olfactory deposits and shielding visual cues, site fidelity was lost. Idiothetic and/or geomagnetic cues are thought to provide spatial references to visual or olfactory landmarks. Altering nest position relative to the arena and changing the geomagnetic field within the arena in our study, however, did nothing to the site fidelity of visually deprived and non-deprived foragers.
We conclude that site fidelity is developed in a visually structured environment but supplemented by an olfactory backup system that is probably based on discrete home range markings rather than radial odour trails. We demonstrate furthermore that the visual component involved in site location can be stored in the memory of individual F. uralensis foragers during a 6-month hibernation period.     

Oviposition preferences in Grapholita molesta: the relative importance of visual and olfactory cues

The oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), is a major pest of fruit trees worldwide. Females oviposit on the young leaves of peach [Prunus persica (L.) Batsch (Rosaceae)] shoots at twilight, when light intensity changes markedly. Previous researches have shown that the oviposition response of this moth is guided particularly by visual and olfactory cues from host plants. However, the relative importance of visual and olfactory cues in their oviposition preference is largely unknown. As a crepuscular moth, how do choices change as light intensity drops rapidly from day to night? In the present study, through two‐choice behavioural experiments, the oviposition responses of G. molesta to visual and olfactory cues (alone or in combination) from peach shoots were tested at four light intensities ranging from daylight to starlight. Grapholita molesta showed similar oviposition responses to plant cues under 1 000, 100, 1 and 0.01 mW m^?2 illumination. Olfactory cues from peach shoots attracted significantly more oviposition than the negative control, whereas visual cues alone did not. Furthermore, olfactory cues were more attractive than visual cues, and no significant interaction was observed between the responses to the two cues. Our findings indicate that G. molesta females mainly rely on olfactory cues to recognize oviposition sites, regardless of differences in light intensity. These results do not provide evidence for attraction to visual cues, but the possibility that the brightness of leaves might be used to guide oviposition is discussed.     

Short-distance homing in the golden hamster after a passive outward journey

The golden hamster carries food back to its nest along a direct path. In a situation combining a passive outward journey with the elimination of visual and various other exteroceptive cues, the subjects continued to return to their nest site and were not influenced by alterations of the earth's magnetic field. Experiments in which the animals started their hoarding trips from a changing point of departure, or were transferred to an unfamiliar experimental space, suggest that they orientate by path integration and that they assess the angular, but not the linear component of a passive outward journey.     

Desert ants learn vibration and magnetic landmarks

The desert ants Cataglyphis navigate not only by path integration but also by using visual and olfactory landmarks to pinpoint the nest entrance. Here we show that Cataglyphis noda can additionally use magnetic and vibrational landmarks as nest-defining cues. The magnetic field may typically provide directional rather than positional information, and vibrational signals so far have been shown to be involved in social behavior. Thus it remains questionable if magnetic and vibration landmarks are usually provided by the ants' habitat as nest-defining cues. However, our results point to the flexibility of the ants' navigational system, which even makes use of cues that are probably most often sensed in a different context.     

Male broad-nosed pipefish Syngnathus typhle do not locate females by smell

Broad-nosed pipefish Syngnathus typhle were used to investigate whether males used scent in their search for mates. When the males in an experiment had access to olfactory cues only, they did not locate females better than they located males. Thus, S. typhle, was less successful in mate search when visual cues were absent.     

Sight or scent: lemur sensory reliance in detecting food quality varies with feeding ecology

Visual and olfactory cues provide important information to foragers, yet we know little about species differences in sensory reliance during food selection. In a series of experimental foraging studies, we examined the relative reliance on vision versus olfaction in three diurnal, primate species with diverse feeding ecologies, including folivorous Coquerel's sifakas (Propithecus coquereli), frugivorous ruffed lemurs (Varecia variegata spp), and generalist ring-tailed lemurs (Lemur catta). We used animals with known color-vision status and foods for which different maturation stages (and hence quality) produce distinct visual and olfactory cues (the latter determined chemically). We first showed that lemurs preferentially selected high-quality foods over low-quality foods when visual and olfactory cues were simultaneously available for both food types. Next, using a novel apparatus in a series of discrimination trials, we either manipulated food quality (while holding sensory cues constant) or manipulated sensory cues (while holding food quality constant). Among our study subjects that showed relatively strong preferences for high-quality foods, folivores required both sensory cues combined to reliably identify their preferred foods, whereas generalists could identify their preferred foods using either cue alone, and frugivores could identify their preferred foods using olfactory, but not visual, cues alone. Moreover, when only high-quality foods were available, folivores and generalists used visual rather than olfactory cues to select food, whereas frugivores used both cue types equally. Lastly, individuals in all three of the study species predominantly relied on sight when choosing between low-quality foods, but species differed in the strength of their sensory biases. Our results generally emphasize visual over olfactory reliance in foraging lemurs, but we suggest that the relative sensory reliance of animals may vary with their feeding ecology.     

Sensilla numbers and antennal morphology of parasitic and non-parasitic bees (Hymenoptera : Apoidea)

The antennal forms and sensilla of 114 species of bees (Hymenoptera : Apoidea), representing all major lineages, were compared to ascertain the relationship between sensory structures and behavior. For all taxa, males and females of parasitic bee species do not differ significantly in the relative sizes of their antennal structures. For non-parasitic species, females have relatively longer scapes, but relatively shorter flagella. There are significant taxonomic effects in these relationships; the family Megachilidae is aberrant. These findings may relate to similarities in search behavior of males (both parasitic and non-parasitic) and parasitic females, which in general may be more dependent on longer-range olfactory cues, while non-parasitic females also use visual cues and contact or short-range olfactory cues. In the family Halictidae, there is a significant association between body-size and density of sensilla placodea. Among non-parasitic female bees, pollen specialists and generalists do not differ in the relative density of sensilla. Parasitic forms in Halictidae, however, have fewer sensilla placodea per unit aarea than do their hosts.     

MPI CyberMotion Simulator: implementation of a novel motion simulator to investigate multisensory path integration in three dimensions

Path integration is a process in which self-motion is integrated over time to obtain an estimate of one's current position relative to a starting point (1). Humans can do path integration based exclusively on visual (2-3), auditory (4), or inertial cues (5). However, with multiple cues present, inertial cues - particularly kinaesthetic - seem to dominate (6-7). In the absence of vision, humans tend to overestimate short distances (<5 m) and turning angles (<30°), but underestimate longer ones (5). Movement through physical space therefore does not seem to be accurately represented by the brain. Extensive work has been done on evaluating path integration in the horizontal plane, but little is known about vertical movement (see (3) for virtual movement from vision alone). One reason for this is that traditional motion simulators have a small range of motion restricted mainly to the horizontal plane. Here we take advantage of a motion simulator (8-9) with a large range of motion to assess whether path integration is similar between horizontal and vertical planes. The relative contributions of inertial and visual cues for path navigation were also assessed. 16 observers sat upright in a seat mounted to the flange of a modified KUKA anthropomorphic robot arm. Sensory information was manipulated by providing visual (optic flow, limited lifetime star field), vestibular-kinaesthetic (passive self motion with eyes closed), or visual and vestibular-kinaesthetic motion cues. Movement trajectories in the horizontal, sagittal and frontal planes consisted of two segment lengths (1st: 0.4 m, 2nd: 1 m; ±0.24 m/s(2) peak acceleration). The angle of the two segments was either 45° or 90°. Observers pointed back to their origin by moving an arrow that was superimposed on an avatar presented on the screen. Observers were more likely to underestimate angle size for movement in the horizontal plane compared to the vertical planes. In the frontal plane observers were more likely to overestimate angle size while there was no such bias in the sagittal plane. Finally, observers responded slower when answering based on vestibular-kinaesthetic information alone. Human path integration based on vestibular-kinaesthetic information alone thus takes longer than when visual information is present. That pointing is consistent with underestimating and overestimating the angle one has moved through in the horizontal and vertical planes respectively, suggests that the neural representation of self-motion through space is non-symmetrical which may relate to the fact that humans experience movement mostly within the horizontal plane.     

Evidence for Resetting the Directional Component of Path Integration in the House Mouse (Mus musculus)

Path integration is the animal's running computation of its position relative to a starting point based on recording all displacements. This process is known to be prone to cumulative errors and hence must somehow be corrected with the help of local spatial cues. In the reported experiments, the relative role of local spatial cues at two target locations was appraised. These two targets were the peripheral box of a female house mouse (Mus musculus) and a central box from where she retrieved her pups over a distance of 50 cm. The experimental conditions required the mouse to navigate between the two targets solely by means of path integration. To find out whether the mice continued integrating at the two target locations, directional misinformation was fed into their path integrating system. Hence, passive rotation of 90° proved to be sufficient to decide unambiguously whether the mice were misdirected. Such experimental interference consistently documented ongoing path integration at the target location outside the residential nest. In contrast, the same interference when the mouse was in the residential nest documented discontinuation of path integration in most cases. It is inferred that mice, when departing from residential nests, initially direct themselves by means of local guiding stimuli.     

Orientation and navigation in Amphibia

Aquatic and terrestrial amphibians integrate acoustic, magnetic, mechanical, olfactory and visual directional information into a redundant-multisensory orientation system. The sensory information is processed to accomplish homing following active or passive displacement by either path integration, beaconing, pilotage, compass orientation or true navigation. There is evidence for two independent compass systems, a time-compensated compass based on celestial cues and a light-dependent magnetic inclination compass. Beaconing along acoustic or olfactory gradients emanating from the home site, as well as pilotage along fixed visual landmarks also form an important part in the behaviour of many species. True navigation has been shown in only one species, the aquatic salamander Notophthalmus viridescens. Evidence on the nature of the navigational map obtained so far is compatible with the magnetic map hypothesis.