Structural consistency of exploratory behaviour of sub-adult and adult spiny mice (Acomys cahirinus) in seven different tests.

The genus Acomys is of growing importance to many research fields. Previous research has shown that individuals differ when exploring new environments and that these behavioural strategies are consistent in time. In this study, we subjected 60 commensal Acomys cahirinus (37 males, 23 females) to a series of seven tests (free exploration, forced exploration under bright illumination, forced exploration under low illumination, hole board test, vertical activity test, elevated plus maze, and voluntary wheel running) to acquire independent behavioural traits and investigate whether and how personality develops in spiny mice. The full series of experiments was performed twice during ontogeny: once in the sub-adult stage (tested at 62-72 days of age) and once in the adult stage (102-112 days of age). We found that behaviour of the animals was repeatable both within (range of R values from 0.155 to 0.726) and across the two life-stages (0.238 to 0.563). While the structure of behaviour in adults was rather clear, it had not been fully crystalized in sub-adults, suggesting personality changes during maturation, even though some individual traits might be repeatable across ontogeny. Notably, the most consistent behavioural traits across the different tests were jumping and rearing, which are not commonly reported.

Measuring fear evoked by the scariest animal: Czech versions of the Spider Questionnaire and Spider Phobia Beliefs Questionnaire.

BACKGROUND: Although tiny in size and mostly harmless, spiders evoke exceptional fear in a significant part of the population and arachnophobia is one of the most common anxiety disorders with prevalence 2.7-6.1%. Two standard measures have been widely used to reliably assess the emotional and cognitive component of spider fear, the Spider Questionnaire (SPQ) and Spider Phobia Beliefs Questionnaire (SBQ). We aimed to develop and validate their Czech translations, describe distribution of spider fear in the Czech population, and analyse its association with disgust propensity and other sociodemographic characteristics. METHODS: In Phase 1, we developed Czech translations of both questionnaires using a back-translation procedure and then tested their psychometric properties against their English versions in a counterbalanced experimental design using the Mann-Whitney U test and two-sided t-test. In Phase 2, we analysed scores on the Czech SPQ and SBQ on a larger sample. We evaluated the effects of age, gender, level of education, biology background, and association with the assessments of snake fear (i.e. the Snake Questionnaire, SNAQ) and disgust propensity (i.e. the Disgust Scale-Revised, DS-R) using a Spearman correlation, redundancy analysis, and general linear models. RESULTS: We have demonstrated that the Czech SPQ and SBQ are equivalent to their originals and show excellent test-retest reliability (SPQ: 0.93; SBQ: 0.87-0.90). In total, 398 (10.3%) out of 3863 subjects reached the cut-off point for potential spider phobia. In addition, SPQ and SBQ scores were highly correlated (0.73-0.79), significantly more than with the SNAQ (0.21-0.32) or the DS-R (0.36-0.40). Two multivariate statistical methods revealed a significant association between the gender, age, level of education, biology background, or disgust propensity and the SPQ scores. CONCLUSION: The Czech SPQ and SBQ may produce reliable and valid assessments of spider fear, but they must be further psychometrically tested considering the limitation of this study before wider use. We corroborate previous findings that fear of spiders is significantly associated with sociodemographic variables, such as gender, age, or education, as well as with the individual level of disgust propensity.

Emotions triggered by live arthropods shed light on spider phobia.

Spiders are mostly harmless, yet they often trigger high levels of both fear and disgust, and arachnophobia (the phobia of spiders) ranks among the most common specific animal phobias. To investigate this apparent paradox, we turned to the only close relatives of spiders that pose a real danger to humans: scorpions. We adopted a unique methodology in order to assess authentic emotions elicited by arthropods. Over 300 respondents were asked to rate live specimens of 62 arthropod species (including spiders, scorpions, cockroaches, and other insects) based on perceived fear, disgust, and beauty. We found that species' scores on all three scales depended on the higher taxon as well as on body size. Spiders, scorpions, and other arachnids scored the highest in fear and disgust, while beetles and crabs scored the highest in beauty. Moreover, all chelicerates were perceived as one cohesive group, distinct from other arthropods, such as insects or crabs. Based on these results, we hypothesize that the fear of spiders might be triggered by a generalized fear of chelicerates, with scorpions being the original stimulus that signals danger.

Relationship between exploratory activity and adrenocortical activity in the black rat (Rattus rattus).

The relationship between physiological and behavioral stress markers is documented in several rodent species. However, there is no information regarding the role of adrenocortical activity in behavior of the black rat (Rattus rattus). Therefore, we hypothesize that the adrenocortical activity of black rats varies between individuals and is related to some of the behaviors in a novel environment. To test this hypothesis, we (i) validated a method for quantifying glucocorticoid metabolites from feces (fGCMs) with an enzyme immunoassay (EIA); (ii) examined variation and diurnal rhythms of feces and GCM production; and (iii) examined the relationship between GCM levels and exploratory behavioral traits. We fulfilled the first aim (i) by successfully performing an ACTH challenge test to validate the use of a 5α-pregnane-3ß,11ß,21-triol-20-one EIA for measuring fGCMs. Second (ii) we detected considerable consistent interindividual variability in production of both feces and glucocorticoids. The peak production of feces occurred in the first hour of the dark cycle, the peak of fGCMs occurred approximately 3 h later. Lastly, (iii) there was no clear relationship between behavior in the hole board test and GCMs. Grooming, a typical behavioral stress marker, was negatively associated with stress reactivity, while head-dipping in the hole-board test (traditionally considered an exploratory behavior independent of stress) was not correlated with the GCMs. This study offers a first look at GCMs in the black rat, successfully validates a method for their measurement and opens possibilities for future research of the relationship between glucocorticoids and exploratory behavior in this species.

On the ground and in the heights: Does exploratory activity differ in commensal and non-commensal spiny mice?

Human settlements represent a specific environment where commensal animals are exposed to different selective pressures than their wild-living conspecifics. Despite the importance of commensal rodents for human health and economy, little is known about how a transition to a commensal way of life changes the behaviour of the animals. We tested twelve populations of spiny mice (Acomys spp.) in two open field-type tests - a vertical test and a hole board test. In the vertical test, a wire mesh for climbing was offered to spiny mice. We used a multipopulation approach using two commensal and ten non-commensal spiny mouse populations to account for inter-population variability. We aimed to investigate whether there are differences in behaviour of commensal and non-commensal populations with special regard to their exploratory activity both on the ground and on the wire mesh. We found that all non-commensal populations behaved similarly despite their long separate evolutionary histories. Contrary, the commensal populations were less exploratory on the ground in both tests. We concluded that this change was associated with their transition to commensalism. This shows that selective pressures of the commensal environment are able to induce noticeable changes in behaviour after a very short evolutionary time.

Venomous snakes elicit stronger fear than nonvenomous ones: Psychophysiological response to snake images.

Snakes have been important ambush predators of both primates and human hunter-gatherers throughout their co-evolutionary history. Viperid snakes in particular are responsible for most fatal venomous snakebites worldwide and thus represent a strong selective pressure. They elicit intense fear in humans and are easily recognizable thanks to their distinctive morphotype. In this study, we measured skin resistance (SR) and heart rate (HR) in human subjects exposed to snake pictures eliciting either high fear (10 venomous viperid species) or disgust (10 nonvenomous fossorial species). Venomous snakes subjectively evaluated as frightening trigger a stronger physiological response (higher SR amplitude) than repulsive non-venomous snakes. However, stimuli presented in a block (more intense stimulation) do not trigger a stronger emotional response compared to sequentially presented stimuli (less intense stimulation). There are significant interindividual differences as subjects with high fear of snakes confronted with images of viperid snakes show stronger, longer-lasting, and more frequent changes in SR and higher HR compared to low-fear subjects. Thus, we show that humans demonstrate a remarkable ability to discriminate between dangerous viperids and harmless fossorial snakes, which is also reflected in distinct autonomous body responses.