Duration of marriages and remarriages in Chiomonte (Turin) in the XVII–XVIII century

This is a preliminary study of the duration of marriages and remarriages by widowed people in Chiomonte (Turin) from 1670 to 1729, a period that saw long periods of war alternating with brief intervals of peace. We analysed 748 marriage acts and evaluated the age at first marriage, the duration of marriage, the frequency of remarriage by widowed people and the number of widowed people who remarried. The data were analysed in five-year intervals. The results show that the population of Chiomonte was essentially permanent, since the end of the marriage could be established in 77,6% of cases. The mean duration of marriages increased from the end of the XVII century and around 51% of all marriages lasted more than 20 years. Historical events had different effects on the matrimonial behaviour. After the mortality crisis in 1690–91, marriages and remarriages increased in 1691–94, a typical response of populations decimated by an epidemic. However, the matrimonial behaviour in the decade 1704–14 was different, in that there was a strong increase in exogamous marriages (56.52% of all marriages). Remarriages, especially of widowed persons, also increased in that period. Although these data are preliminary and from a brief time period, they reveal particular aspects of the marriage and remarriage behaviour, thus helping to clarify the biodemographic evolution of the Chiomonte population.     

The influence of marking upon bee behaviour in circle tube experiments with a methodological comparison among studies

Summary. Circle tubes were used to investigate the influence of marking upon the behavioural profiles of two halictid species; one, Penapis toroi Rozen, putatively solitary, the other, Corynura chloris (Spinola) thought to be semisocial. Previous studies have shown that solitary bees tend to exhibit avoidance behaviour and those with a reproductive division of labour tend to behave aggressively within circle tube arenas. Marked pairs of C. chloris were significantly more cooperative than unmarked pairs and marked P. toroi showed significantly increased aggression and decreased cooperation. These findings suggest that marking bees may reduce behavioural differences among taxa with different types of social organization. Recommendations are made on how to use the circle tube apparatus to detect bee populations that might be worth more detailed studies of social organization and also for standardization in the way results of these studies are presented. Further experiments are suggested to clarify the effects of certain variables upon bee behaviour using this apparatus. The data presented here are the first for any member of the subfamily Rophitinae and the first for any bee thought to be primarily semisocial. A narrower range of behaviours were observed in the Rophitine, Penapis toroi Rozen, in comparison to species from other subfamilies of Halictidae and Corynura chloris Spinola had a behavioural profile similar to that of eusocial species.Received 15 December 2003; revised 12 September 2004; accepted 15 October 2004.     

Queen size dimorphism in the ant Tetramorium moravicum (Hymenoptera, Formicidae): Morphometric, molecular genetic and experimental evidence

Summary. By combining different methods we evaluate whether the ant Tetramorium rhenanum is specifically separated from T. moravicum or whether it is a conspecific microgyne form. High-precision morphometry shows a clear difference in queen size. Sequence comparison of 1031 bp of COI reveals that T. rhenanum falls into a clade with T. moravicum, which is significantly separated from T. forte and T. chefketi. T. rhenanum shares at least two haplotypes with T. moravicum and is considered as a junior synonym. Sexual behaviour and colony foundation experiments corroborate conspecificity. The queen dimorphism is discussed in the context of social parameters such as queen number and reproductive strategy.Received 10 June 2004; revised 28 October 2004; accepted 12 November 2004.     

Swim or hide: predator cues cause species specific reactions in young fish larvae

The anti‐predator behaviour of first‐feeding (9 mm total length) hatchery‐reared pike Esox lucius larvae and wild‐caught three‐spined stickleback Gasterosteus aculeatus larvae was studied in the presence of chemical and visual signals from a fish predator. The results clearly showed that both fish species detected the predator by chemical signals alone but the combined chemical and visual signals caused stronger and more diverse reactions. Subsequent to predator detection, their swimming activity decreased, they attacked zooplankton less frequently and spent more time in the vegetation. Fishes differed in their anti‐predator responses. Pike reacted more clearly to chemical signals alone while three‐spined stickleback needed both chemical and visual cues to assess the predation risk. The strongest reaction was the reduction in swimming activity in the three‐spined stickleback (38% decrease) and a decrease in attack rate of the pike (39% decrease), but only when a refuge was available. Pike were more dependent on the vegetation cover showing almost no anti‐predator responses in the absence of a refuge. In addition, there was a difference in the refuge use of three‐spined stickleback between different macrophytes, indicating a complex or dense structure, which was difficult to penetrate or chemical excretion in one of them.     

The effect of sex and shoal size on shoaling behaviour in Danio rerio

Male and female zebra fish Danio rerio were given choices of shoals that differed in sex and size. Male zebra fish preferred to associate with female shoals over male shoals, but had no preference when given a choice between a mixed‐sex shoal and either a male or female shoal. Female zebra fish showed no significant preference when given a choice between male and females shoals, nor between mixed‐sex shoals and either male or female shoals. When given choices between shoals of differing size, females preferred to associate with the larger shoal, whether or not they were composed of males or females. Males, however, had no preference for larger shoals over smaller shoals, whether or not they were composed of males or females. These results showed that male zebra fish were capable of distinguishing between males and females solely on the basis of visual cues. Furthermore, these results demonstrated a significant difference between the shoaling choices of male and female zebra fish, which may indicate a difference in the function of shoaling for the two sexes.     

Significance of a new field oviposition record for Graphium eurypylus (L.) (Lepidoptera: Papilionidae) on Michelia champaca (Magnoliaceae)

Abstract  Phytochemical similarities among ancient Angiosperms presumably played a role in the ecological and evolutionary diversification of the swallowtail butterflies (Papilionidae). Host family feeding specialisation is typical of most Papilionidae species, but field records of oviposition are rare for most swallowtail butterflies. It is even more uncommon to witness oviposition and larval feeding on new host plant species, especially in plant families not previously reported for the butterfly species. Oviposition by a female on a new host, or even on a toxic plant, may represent ancestral behaviour (with a loss of larval acceptance, detoxification or processing abilities) or novel behaviour (providing genetic variation for a potential expansion of host range, or host shift). We document the oviposition, larval use and pupation of the Annonaceae specialised and geographically widespread Graphium eurypylus on a Magnoliaceae species, all under field conditions in Queensland, Australia. This is the first time such field observations of oviposition and larval feeding on Michelia champaca (Magnoliaceae) have been documented anywhere for this species.     

Linking traits of foraging animals to spatial patterns of plants: social and solitary ants generate opposing patterns of surviving seeds

Foraging traits of seed predators are expected to impact the spatial structure of plant populations, community dynamics and diversity. Yet, many of the key mechanisms governing distance- or density-dependent seed predation are poorly understood. We designed an extensive set of field experiments to test how seed predation by two harvester ant species interact with seed dispersal in shaping the spatial patterns of surviving seeds. We show that the Janzen–Connell establishment pattern can be generated by central-place foragers even if their focal point is located away from the seed source. Furthermore, we found that differences in the social behaviour of seed predators influence their sensitivity to seed density gradients and yield opposing spatial patterns of surviving seeds. Our results support the predictions of a recent theoretical framework that unifies apparently opposing plant establishment patterns, and suggest that differences in foraging traits among seed predators can drive divergent pathways of plant community dynamics.     

Behavioural responses of wheat stem sawflies to wheat volatiles

1 Adult wheat stem sawflies Cephus cinctus, pests of cultivated cereals that also infests wild grasses, migrate into wheat fields where they oviposit in elongating, succulent stems.
2 Volatiles released by wheat plants at susceptible stages were analyzed to determine potential semiochemical compounds. Seven major compounds were identified and quantified.
3 A Y-tube bioassay was developed to evaluate upwind orientation of adult sawflies in response to an airstream that passed over elongated wheat plants. The bioassay was also conducted with synthetic volatile compounds. The compounds were tested using a range of concentrations spanning those identified in the airstream passing over wheat plants.
4 A significant number of adult females were attracted to wheat plants when given a choice of either purified air or the air passing over plants.
5 A significant number of female C. cinctus were attracted to ( Z )-3-hexenyl acetate, β-ocimene, and ( Z )-3-hexen-1-ol, but were repelled by 6-methyl-5-hepten-2-one. Females did not respond to ( E )-2-hexenal, or ( E )-2-hexenyl acetate. The behavioural responses were concentration dependent; the highest tested concentration of ( Z )-3-hexenyl acetate was repellent to females of this species.
6 Adult males did not discriminate between air passing over wheat plants and air from a purified airstream. Males did not respond to any tested synthetic compound at any concentration.
7 The present study demonstrates for the first time that adult females of wheat stem sawfly display innate behaviours in response to synthetic volatiles. These results provide a basis for the potential development of resistant wheat varieties and for the development of semiochemically-based pest management.     

Spatial and temporal distribution of Empoasca vitis within a vineyard

1 The intra‐plot spatial distribution of the green leafhopper Empoasca vitis (Goethe) (Cicadellidae, Empoascini) was assessed over three successive growing seasons in a Bordeaux vineyard. Weekly measurements of adult trappings and nymphal counts were performed in a 1.7‐ha plot on 130 sampling points. 2 Statistical and geostatistical analyses revealed inconsistent spatial distributions of adults and nymphs in spring, but consistent spatial distributions in summer, which were identical every year. 3 Similarities between spatial distributions of the mobile adults and the sedentary and aggregated nymphs strongly suggest that adults disperse inside the plot to areas preferred for egg deposition. 4 The similarity of summer populations among years suggests that this insects distribution is based on (perennial) differences in plot characteristics.