Modulation of individual behavior and collective decision-making during aggregation site selection by the ant<Emphasis Type="Italic"> Messor barbarus</Emphasis>

Insect societies are often confronted with choices among several options such as food sources of different richness or potential nest sites with different qualities. The mechanisms by which a colony as a whole evaluates these situations and takes the appropriate decision are of crucial importance for its survival. Here we studied how collective decisions arise from individual behaviors when a group of workers of the ant Messor barbarus is given a choice between two aggregation sites. Two hundred ants were introduced into an arena and given a choice between two tubes connected to the arena. The tubes had different physical properties: dry and transparent (termed as dry), humid and transparent (termed as humid), or dry and dark (termed as dark). After 30 min, most ants were found to be aggregated in a humid tube when paired with a dry tube, or in a dark tube when paired with a humid one. When two humid tubes were in competition, ants aggregate more in one of the sites. The choice of ants was consistent throughout experiments. An analysis of individual behaviors shows that the probability of an ant recruiting and the intensity of its trail-laying behavior strongly depend on the quality of the tubes. Our study suggests that the selection of an aggregation site does not require that individual ants directly compare sites, but rather relies on the synergy between amplification processes involving recruitment by chemical trails, and a modulation of the individual resting time in a site as a function of its population.Communicated by L. Sundström     

Manipulation of nest-box density affects extra-pair paternity in a population of blue tits (<Emphasis Type="Italic">Parus caeruleus</Emphasis>)

We tested the effect of manipulation of breeding density on the occurrence of extra-pair paternity in a blue tit (Parus caeruleus) population during two consecutive years. In a homogeneous oak forest, nest-box manipulation provided a high density plot (plot A, 1.10 and 1.32 pairs/ha) and a low density plot (plot B, 0.43 and 0.46 pairs/ha). Microsatellite analysis on 91 broods revealed a higher proportion of extra-pair paternity in broods in plot A (mean of 17.2%) than in plot B (mean of 11.4%). A correlative approach showed that the proportion of extra-pair young in broods was affected by the number of breeding neighbours within 100 m around the nest-box, by the distance to the nearest breeding neighbour and by an additional plot effect. However, the nearest neighbours accounted for only 39.3% of extra-pair paternities and distance to extra-pair fathers was significantly higher than the nearest neighbour distance in both plots. This implies that the effect of density on the occurrence of extra-pair paternities is associated with active female choice to enhance the brood fitness. Although there were more extra-pair young in broods when density was high, the number of extra-pair fathers did not increase and stayed close to one. We suggest that density increases the cost of mate guarding by males, thereby increasing the possibility for females to solicit extra-pair paternities to the cuckolding male they have chosen. Finally, we discuss why correlatives approaches do not always show evidence for an effect of breeding density on extra-pair paternity occurrence.Communicated by M. Soler     

Within-brood patterns of paternity and paternal behavior in red-winged blackbirds

We video-taped male and female red-winged blackbirds (Agelaius phoeniceus) feeding individual chicks in order to test the hypothesis that food might be differently allocated to within-pair offspring and extra-pair young. We found no evidence that paternity influenced the allocation of food by either males or females. Both males and females fed male offspring significantly more, but there was no tendency for paternity to be skewed by gender. Females fed older offspring significantly more, whereas males did not; extra-pair fertilizations, however, were not associated with lay or hatch order of the chicks. Given that males do not appear to discriminate within-pair from extra-pair offspring directly, these results are consistent with current theory on the effect of paternity on paternal behavior. We discuss briefly some of the possible reasons why discrimination might be lacking in red-winged blackbirds and in other species in which the possibility of discrimination of paternity and allocation of paternal behavior has been studied.     

A comparison of amniotic fluid alpha-fetoprotein and acetylcholinesterase in the prenatal diagnosis of open neural tube defects and anterior abdominal wall defects

Amniotic fluid samples received for routine prenatal diagnosis of open neural tube defects were used for a study to compare amniotic fluid acetylcholinesterase (AChE) determination using a monoclonal antibody (4F19) enzyme antigen immunoassay and amniotic fluid alpha-fetoprotein (AFP) measurement as diagnostic tests for open neural tube defects. The study was based on 9964 women with singleton pregnancies and known outcome (including 6 with anencephaly and 18 with open spina bifida) having an amniocentesis at 14–23 weeks of gestation. The AChE immunoassay yielded detection rates for anencephaly of 100 per cent (95 per cent confidence interval (CI) 54·07–100 per cent), for open spina bifida of 100 per cent (95 per cent CI 81·47–100 per cent), for anterior abdominal wall defects of 20 per cent (95 per cent CI 0-51-71-64 per cent), and a false-positive rate of 0·22 percent (95 per cent CI 0·14–0·34 per cent) excluding anencephaly, open spina bifida, and anterior abdominal wall defects. For similar detection rates the false-positive rate of the AFP test was significantly higher, 0·74 per cent (95 per cent CI 0·58–0·94 per cent). On the basis of these findings, it is recommended that the technically simple AChE immunoassay should be used on all samples; the AFP test should only be used on the 0·5 per cent of the samples with concentrations of AChE activity ⩾ 8·5 nkat/1 for clear samples and blood-stained samples becoming clear after centrifugation, and ⩾ 25·0 nkat/1 for blood-stained samples that are discoloured after centrifugation; an AFP cut-off level of 2·0 MOM is recommended for this policy. Thereby, the detection rates for anencephaly, open spina bifida, and anterior abdominal wall defects would be 100, 100, and 20 per cent, respectively (95 per cent CIs 54·07–100, 81·47–100, and 0·51–71·64 per cent, respectively), and the false-positive rate would be 0·08 per cent (95 per cent CI 0·03–0·16 per cent) (excluding anencephaly, open spina bifida, and anterior abdominal wall defects).     

Thriving at work: A meta‐analysis

Thriving at work refers to a positive psychological state characterized by a joint sense of vitality and learning. On the basis of Spreitzer and colleagues' model, we present a comprehensive meta‐analysis of antecedents and outcomes of thriving at work (K = 73 independent samples, N = 21,739 employees). Results showed that thriving at work is associated with individual characteristics, such as psychological capital (r_c = .47), proactive personality (r_c = .58), positive affect (r_c = .52), and work engagement (r_c = .64). Positive associations were also found between thriving at work and relational characteristics, including supportive coworker behavior (r_c = .42), supportive leadership behavior (r_c = .44), and perceived organizational support (r_c = .63). Moreover, thriving at work is related to important employee outcomes, including health‐related outcomes such as burnout (r_c = ?.53), attitudinal outcomes such as commitment (r_c = .65), and performance‐related outcomes such as task performance (r_c = .35). The results of relative weights analyses suggest that thriving exhibits small, albeit incremental predictive validity above and beyond positive affect and work engagement, for task performance, job satisfaction, subjective health, and burnout. Overall, the findings of this meta‐analysis support Spreitzer and colleagues' model and underscore the importance of thriving in the work context.     

Test of the Multi Increment Sampling® Method on 14 Playgrounds

The Capital Region of Denmark tested the Multi Increment Sampling^® (MIS) technology at 14 children's playgrounds in the region to assess whether the method provides representative test results and an improved foundation for risk assessment. The purpose of the investigation was to determine whether the previous uses of the playground areas have led to soil contamination that poses a health risk to its current users (children). The unpaved areas of the playgrounds were divided into decision units based on historical data along with the expected patterns of movement from its users. The samples from each unit consisted of 45 to 100 increments were collected from three depths within the upper one‐half meter. Furthermore, triplicate samples were taken from the upper sampling depth in at least one unit for quality control purposes. The investigation results showed excellent consistency between the pollution parameters and contamination levels in different decision units for each playground. The decision units where high levels of soil contamination exist coincide well with the previous site history. The MIS method has proven to be expensive and time consuming. However, in the future it will be easier to implement as we gain more experience with use of this method.  ©2016 Wiley Periodicals, Inc.     

Flammability of Some Ornamental Species in Wildland–Urban Interfaces in Southeastern France: Laboratory Assessment at Particle Level

Assessment of the flammability of ornamental vegetation (particularly hedges) planted around houses is necessary in light of the increasing urbanization of the wildland–urban interfaces (WUIs) and the high fire occurrence in such areas. The structure and flammability of seven of the species most frequently planted as hedges in Provence (southeastern France) were studied at particle level. Spatial repartition of the different types of fuel particles within plants was assessed by means of the cube method. The leaf flammability was assessed using an epiradiator as a burning device, and measurements of foliar physical characteristics and gross heat of combustion (GHC) helped to explain the results of burning experiments. Co-inertia analysis revealed that species with thin leaves were quick to ignite (Pyracantha coccinea, Phyllostachys sp.) and species with high leaf GHC burned the longest (Pittosporum tobira, Nerium oleander). Species presenting high ignitability (Photinia fraseri, Phyllostachys sp. and Pyracantha coccinea) were characterized by high foliar surface area-to-volume ratio, and species presenting lower ignitability were characterized by high GHC (Pittosporum tobira, Nerium oleander, Cupressus sempervirens). Hierarchical cluster analysis of the flammability variables (ignition frequency, time-to-ignition and flaming duration) categorized the relative flammability of the seven species (including dead Cupressus sempervirens) in five clusters of species from poorly flammable (Pittosporum tobira) to extremely flammable (dead Cupressus sempervirens).This study provides useful information for reducing fire risk in WUIs in the study area.