Marco Zaccaroni

Early exposure to low doses of atrazine affects behavior in juvenile and adult CD1 mice

Environmental exposure to endocrine disrupting chemicals is receiving increasing attention, with particular regard to distinct periods of development where neuroendocrine circuitries are critical for shaping the mammalian brain. Atrazine (ATZ), a widely used herbicide, has been reported to affect steroid hormones and interfere with pathways critical for sex-specific physiological and behavioral development. Aim of the present study was to evaluate effects of perinatal exposure to environmentally relevant subtoxic doses of ATZ, on neurobehavioral development in mice and investigate possible alterations in steroid hormone metabolism. Neurobehavioral development of female and male mice delivered from CD1 dams, and daily exposed from Gestational Day 14 until Postnatal Day 21 (PND 21) to 1 or 100 μg/kg bw ATZ, was investigated. Specifically, locomotor and exploratory activity, social interactions and cognitive performance were evaluated at PND 16, 31 and 60, respectively. Moreover, general toxicity clinical signs, testicular parameters, rate of testosterone metabolism and aromatase activity in F1 male liver were analyzed at adulthood. Changes in exploratory profile and in affiliative/investigative behavior were observed, revealing a feminization of behavioral profile in ATZ-exposed males. Alteration in learning performance at adulthood was also evident. A limited decreased sperm count and concentration, as well as some slight impairment in hepatic testosterone metabolism and in aromatase activity (slightly but not significantly decreased) were observed in both low and high dose exposed animals. In conclusion developmental exposure to non-toxic, environmentally relevant doses of ATZ can produce subtle functional alterations, detectable in juvenile rodents by a detailed behavioral analysis. Behavioral disturbances appeared mainly related with neurodevelopmental disorder affecting the social domain and the emotional/affective repertoire, although further research is needed to elucidate the mechanism through which the effects are induced.

Group specific vocal signature in free-ranging wolf packs

Acoustic communication conveys a variety of information that is a helpful tool for animal conservation. The wolf is an elusive species, which can be detected through the howls that individuals emit. In this study we investigated the acoustic features of wild wolf pack howls from five locations in the province of Arezzo, Italy. We tested the hypothesis that each group had a distinctive vocal signature. Our results showed that these wolf packs emitted howls with significantly distinctive acoustic structures. We hypothesized that group-specific vocal signatures require temporal stability to be functional. Indeed, we did not find any statistical differences in howls collected from the same location during the same season or for 2 consecutive years. We suggest that the acoustic features of howls can be used to distinguish wolf packs in the wild.

THE ACOUSTIC STRUCTURE OF WOLF HOWLS IN SOME EASTERN TUSCANY (CENTRAL ITALY) FREE RANGING PACKS

ABSTRACT Italian wolf howls are described for the first time from observations between 2003–2008 of a population living in eastern Tuscany, central Italy. A sample of 37 howls selected among single responses and 128 howls included in the choruses of 7 free ranging packs was recorded and analysed. The mean fundamental frequency of the howls ranged between 274–908 Hz. Two main structures recognised by means of multivariate explorative analysis, in particular Principal Component and Cluster Analysis, were ascribed to breaking and flat howls. Discriminant Function Analysis was applied to the recognised groups with the aim to find a general rule for classification. Howls with different features were correctly assigned to the groups obtained by explorative analysis in 95.8% of cases. The analysis of the variables characterising the structure of the howls suggests that maximum frequency and range of fundamental frequency are the most important parameters for classification, while duration does not appear to play any significant role.

Effects of low doses of atrazine on the neurobehavioural development of mice

Recent studies suggest that atrazine (ATZ), a triazine herbicide widely used and frequently detected in ground and surface water, is able to affect estrogen production by inducing aromatase, the enzyme that converts androgen into estrogen, an essential transformation occurring at the CNS level for maturation and expression of behaviour. In the present study we evaluated the effects of environmentally relevant doses of ATZ on somatic growth and early behavioural ontogeny, a crucial stage in shaping future behaviour. For this purpose we observed mice born to mothers exposed to 1 or 100 µg/kg ATZ during pregnancy and lactation. We studied, between postnatal day 2 to 15, the righting reflex, cliff aversion, forepaw grasping, auditory startle, eyelid and ear opening, and ultrasound vocalizations. In both sexes ATZ effects were evident, on body weight at birth, on the maturation of righting and grasping reflexes, and on the rate of emission and the spectrographic characteristics of ultrasound vocalizations. Dosage level appeared to be particularly relevant because, in some cases, the lower ATZ exposure was more effective than the higher one in modifying behavioural response. The latter finding suggests that this compound, similarly to many others endocrine disruptors, does not follow a linear dose-response curve, and that, as a consequence, its effects should be studied carefully at very low doses. Our results, compatible with ATZ properties, suggest caution in the use of a chemical agent that may, even at low doses, interfere with brain development and differentiation, inducing alterations of the developmental trajectories of behaviours.

Anti-predator behaviour of the red-legged partridge Alectoris rufa (Galliformes: Phasianidae) to simulated terrestrial and aerial predators

Abstract This study is intended to investigate the differences in anti-predator behavioural and acoustic response to terrestrial and aerial predators as well as the behavioural differences between sexes in the red-legged partridge. To this aim we observed the response of 114 partridge (57 males and 57 females) to dummy terrestrial and aerial predators, a raptor and a fox. We divided behavioural responses to predators into four mutually exclusive categories: vigilance, freezing, escape and non-anti-predator behaviours. We also recorded and analysed the vocalizations emitted during tests. The animals reacted differently to aerial and terrestrial stimuli. The reactions elicited by the terrestrial predator were ranked as follows: vigilance, escape, non-anti-predator behaviours, and freezing. Those elicited by the aerial predator were ranked as follows: vigilance, freezing, escape and non-anti-predator behaviours. Vigilance and escape were elicited more frequently by the terrestrial predator than by the aerial predator (vigilance: p < 0.001; escape: p < 0.001). Freezing was the most frequent behaviour following the appearance of the aerial predator (p < 0.001). In fact, freezing may represent an effective strategy in an open space, combining camouflage from and detection by the predator. On the other hand, vigilance is an effective behaviour to detect and avoid a terrestrial predator hunting by ambush. We did not find clear-cut differences between sexes. The analysis of vocalizations revealed that the fox and the raptor elicited significantly different calls (p = 0.003); the fox evoked significantly more vocalizations than the raptor (p< 0.001), differing in addition in frequency parameters. Thus partridges not only discriminate between aerial and terrestrial predators and behave consequently, but are also able to tune alarm calls in relation to the context of predation.

Demographic parameters of reintroduced grey partridges in central Italy and the effect of weather

Grey partridge populations declined in Europe from mid-1950s onwards mostly due to modifications of agricultural cropping. In Italy, the decline was even more dramatic because of over-hunting and restocking with allochthonous birds. We carried out a research on a re-introduced population in Central Italy from 1995 to 2005, with the aim of evaluating the reintroduction success and separating the intrinsic and external factors influencing year-to-year changes in partridge density with particular respect to the weather. Average spring density was 4.5 pairs per square kilometre (SD = 1.52); our population reached a peak few years after the reintroduction and then declined. Brood production rate was close to that of declining European populations (average 33.9%; SD = 10.21), and chick survival rate (average 40%; SD = 17.61) determined the change of breeding abundance from year t to year t + 1. Our population seemed to be mainly affected by brood production and chick survival rates and by the weather; in particular, higher early winter and spring temperatures increased breeding density whilst higher early summer temperatures decreased brood production rate.

The fast and the flexible: cognitive style drives individual variation in cognition in a small mammal

Patterns of individual differences in cognition have been studied empirically and systematically in the last decade, but causes and consequences of this variation are still largely unclear. A recent hypothesis suggests that one predictor of individual variation in cognition is personality, and specifically that personality types are linked to cognitive styles through a speed–accuracy trade-off. We tested specific predictions of this hypothesis, measuring individual differences in associative learning speed and flexibility, quantified via reversal learning, of 86 bank voles, Myodes glareolus , along with their activity and boldness. We found that bolder and more active individuals were fast, inflexible and persistent in the associative learning tasks, whereas shyer and less active individuals were slow and flexible. We also found evidence for a speed–accuracy trade-off: correct choices in the cognitive tasks required more time for all individuals compared to incorrect choices, but bolder, more active voles always made their decisions faster than reactive ones. The difference between the time required for a correct and an incorrect choice was most pronounced in initial learning for shyer and less active individuals, but for bolder, more active individuals it was most pronounced in the reversal learning task. We also found differences related to sex and age: females were faster than males to update information or correct incorrect choices and older animals took longer to initiate the test. Our results confirm the hypothesis that individual differences in behaviour are reflected in different ‘cognitive styles’, differentially trading off speed for flexibility and accuracy in cognitive tasks. Moreover, we provide the first evidence for the mechanisms of such a trade-off in a small mammal.

From biology to management of Savi's pine vole (Microtus savii).

Savis pine vole (Microtus savii) is a rodent species of the Cricetidae family, inhabiting southern European agroecosystems. It is considered to be the main cause of rodent-attributed damage in Italy. To achieve an effective management, detailed knowledge of this species is needed. However, the available information about this species is fragmentary and incomplete. In this paper, the existing knowledge of Savis pine vole taxonomy, reproduction, population dynamics, habitat and food preferences is reviewed in order to organise available information and identify priority areas of future research. Some of the changes in farming practices that have occurred in recent decades may have increased the impact of Savis pine vole populations in crop fields. To manage this pest species effectively, an integrated strategy is recommended (involving habitat management, trapping and, when appropriate, the use of rodenticides). The apparent lack of cyclical population outbreaks and the relatively small litter size and long gestation and interpartum period of this species suggest that it could be more manageable than other vole species, while its strict herbivorous diet, stable population size in open habitats and wide distribution seem to indicate it as an ideal model species for risk assessment studies.

From biology to management of Savi's pine vole (Microtus savii): a review

Savis pine vole (Microtus savii) is a rodent species of the Cricetidae family, inhabiting southern European agroecosystems. It is considered to be the main cause of rodent-attributed damage in Italy. To achieve an effective management, detailed knowledge of this species is needed. However, the available information about this species is fragmentary and incomplete. In this paper, the existing knowledge of Savis pine vole taxonomy, reproduction, population dynamics, habitat and food preferences is reviewed in order to organise available information and identify priority areas of future research. Some of the changes in farming practices that have occurred in recent decades may have increased the impact of Savis pine vole populations in crop fields. To manage this pest species effectively, an integrated strategy is recommended (involving habitat management, trapping and, when appropriate, the use of rodenticides). The apparent lack of cyclical population outbreaks and the relatively small litter size and long gestation and interpartum period of this species suggest that it could be more manageable than other vole species, while its strict herbivorous diet, stable population size in open habitats and wide distribution seem to indicate it as an ideal model species for risk assessment studies.

Experimental male size manipulation in Polistes dominula paper wasps: being the right size

In previous studies on Polistes dominula paper wasps, male size affects both mating success and territorial strategy. Larger males occupy exclusive territories at leks, i.e. landmarks where they achieve most copulations (Residents), while smaller males search for females in sub-optimal locations across territories as Transients. We here observed spatial and mating behaviour of a selected size-bimodal population of males, caught at leks and released in semi-natural conditions. Residents, mainly Large males, were more successful in sexual interactions with virgin females than Transients. Residents also engaged in ‘mate guarding’, reported here for the first time. On the other hand, some Small males achieved copulations inside their own territories, at foraging sites or by grasping females and falling on the ground. Both tactics of mate access – patrolling a territory for perched females or intercepting females – were successful, the former more than the latter, whereas size itself was irrelevant to sexual performance and mating success, regardless of our size-bimodal sample. Moreover, we carried out morphological analysis of male reproductive apparatus. Males with larger accessory glands, directly involved in reproductive success in many insects, mated more than males with smaller accessory glands, regardless of male body size.