The relationship between conspecific superparasitism and the outcome of in vitro contests staged between different larval instars of the solitary endoparasitoid Venturia canescens

When endoparasitoid wasps oviposit into hosts which have already been parasitized (= superparasitism), this results in potentially lethal interlarval competition. For solitary species, the decision to lay additional eggs should therefore be based on the probability of superparasite survival in any superparasitized host. In this study, in vitro contests staged between three larval instars of Venturia canescens Grav. (Hymenoptera: Ichneumonidae) reveal that the age difference between competitors affects the outcome of interlarval competition. Three parameters were used to assess parasitoid performance: the number of fights initiated, the number of bites inflicted, and the duration of each bite. When fighting takes place between two first instars, then both competitors were found to be evenly matched. However, at greater age differences, first-instar competitors appeared to win more fights than their larger second instar rivals. The advantage shown by younger competitors is most pronounced in contests staged between first and third instar larvae. These findings are consistent with the increasingly high levels of conspecific superparasitism shown by V. canescens in the first 5 days after initial host attack, suggesting that this parasitoid can deploy her use of deliberate superparasitism in an adaptive way. Received: 13 December 1995/Accepted after revision: 5 March 1996     

Soy production and certification: the case of Argentinean soy-based biodiesel

With the rising emphasis on biofuels as a potential solution to climate change, this paper asks whether certification schemes, developed to promote sustainable feedstock production, are able to deliver genuine sustainability benefits. The Round Table on Responsible Soy (RTRS) is a certification scheme that aims to promote responsible soy production through the development of principles and criteria. However, can and does this initiative address the negative impacts associated with the intensive production of soy? Taking the example of soy biodiesel produced in Argentina, this paper asks whether the social and environmental impacts of soybean production can be mitigated by the RTRS. It concludes that at present certification schemes are unlikely to be able to address either the institutional challenges associated with their implementation or the detrimental impacts of the additional demand generated by biofuels.     

Male coalitions and female behaviour affect male mating success independent of dominance rank and female receptive synchrony in wild Barbary macaques

Dominant mammalian males should gain a reproductive advantage due to their greater fighting abilities. However, the extent to which they can monopolise access to females varies across species. In primates and recently other mammalian species, the Priority of Access (PoA) model is commonly used to measure the degree to which male rank and female receptive synchrony affect mating skew. Few studies have examined the factors which lead to deviations from the expectations of the model. Here, we investigate male mating skew in wild Barbary macaques (Macaca sylvanus). We examined four of the main factors which affect male mating success: the roles of male rank, female receptive synchrony, coalitionary activity and female behaviour. We found that male mating was skewed up the hierarchy, but there was a large deviation from the PoA model's expectations with high-ranked males not gaining as big a share as expected. Females frequently initiated sexual encounters, predominantly with mid-ranked males, increasing their mating success. Male coalitionary activity independently increased mating success. Frequent associations with females were costly to males as they were the targets of bridging coalitions, decreasing future mating opportunities for the targets. High-ranking males did not increase their mating success directly through bridging coalitions but acted to dilute the effects of female behaviour. By examining different factors affecting mating skew, we are able to show that alternative male and female mating strategies are effective in reducing the monopolisation potential of the dominant male.     

Social monitoring in a multilevel society: a playback study with male Guinea baboons

Keeping track of social interactions among conspecifics is a driving force for the evolution of social cognition. How social cognition, such as social knowledge, ties in with a species' social organization is, however, largely unexplored. We investigated the social knowledge of wild Guinea baboons (Papio papio) ranging in Senegal, a species that lives in a fluid multilevel society with overlapping habitat use. Using playback experiments, we tested how adult males differentiate between subjects from their own vs. a neighboring or a stranger social unit (“gang”) and assessed ranging patterns with Global Positioning System (GPS) data. While territorial species usually differentiate between group and nongroup members and often respond more strongly to strangers than neighbors (the “dear enemy” effect), subjects in this highly tolerant species should largely ignore other unit members and mainly attend to subjects from their own unit. Males responded strongly after playback of calls recorded from members of their own gang, while they attended only briefly to neighbor or stranger calls. Apparently, males benefit from monitoring the social maneuvers in their own social unit, while it remains to be resolved whether they are unmotivated or unable to keep track of the identities and actions of individuals outside their own gang. The study highlights how the allocation of social attention is tuned to the specifics of a species' social organization, while a complex social organization does not necessarily translate into the need for more elaborate social knowledge.     

Metal inclusion in expanded clays

The possibility to include in expanded clay little amounts of metallic ions present in waste material, without significant influence on the environment, was investigated. In this article, known quantities of cadmium(II), lead(II), chromium(III), and chromium(VI) were added to a mixture of raw pit clay, adding a small amount of mineral oil. The resultant paste was heated at 1200°C, in conditions to provide the commercial product with the best characteristics of lightness. The obtained pellets were analyzed in two ways. A sample of expanded clay was crushed, added to with KNaCO₃ and melted. The melted mass, after cooling, was dissolved in HCl or in water and analyzed. The composition of the raw pit clay was analyzed as a blank. In parallel, pellets were subjected to a leaching process and the eluate was analyzed for the added cations. The concentration of the metal ions in the leached water is negligible compared with that generally admitted in drinking water.     

Distraction in older drivers - A face-to-face interview study

The prevalence of older drivers’ engagement in distracting activities while driving is largely unexplored. Face-to-face interviews were conducted in the city of Braunschweig, Germany, comparing a sample of older drivers (n = 205) to a group of middle-aged drivers (n = 209). The drivers were interviewed on their engagement in distracting activities during the last half an hour of their driving trip, including the frequency and duration of these activities, their perception of the risk associated with these distracting activities and the role of these activities in at-fault crashes. Middle-aged drivers were significantly more likely to engage in certain distracting activities than older drivers. With regard to the duration of interactions with the passengers older drivers were significantly more talkative than middle-aged drivers. Middle-aged drivers rated most of the distracting activities as significantly less dangerous than older drivers. Distraction-related crashes are not a special problem of older drivers but seem to be very comparable to the middle-aged drivers. It is concluded that older drivers’ reluctance to engage in distracting tasks while driving is either a process of self-regulation or their age-related prudence. The study is the first to gather knowledge about distraction in German older drivers. Although older drivers are not currently overrepresented in distraction-related crashes, it is important to note that future cohorts of older drivers might differ in the way they engage with vehicles and technologies, which in turn may influence their driving patterns and willingness to engage in potentially distracting activities.     

新疆孔雀河表层沉积物中有机氯农药的分布及风险评价

分析了新疆孔雀河9个表层沉积物样品中22种有机氯农药(OCPs)含量,其主要OCPs含量的顺序为:六六六>异狄氏剂醛>滴滴涕>艾氏剂>硫丹Ⅱ>异狄氏剂>氯丹.研究表明,近期有γ-HCH输入到孔雀河,其最可能的来源是博斯腾湖的补给或孔雀河附近的农业回流水.滴滴涕的组成特征分析表明,DDTs主要源于施用的农药在好氧环境土壤中的分解,产生DDE等主要产物.风险评价表明,污染物的风险较低,所有被评估的OCPs的风险值均小于风险评价高限(ERM).     

A review of the health impacts of barium from natural and anthropogenic exposure

There is an increasing public awareness of the relatively new and expanded industrial barium uses which are potential sources of human exposure (e.g., a shale gas development that causes an increased awareness of environmental exposures to barium). However, absorption of barium in exposed humans and a full spectrum of its health effects, especially among chronically exposed to moderate and low doses of barium populations, remain unclear. We suggest a systematic literature review (from 1875 to 2014) on environmental distribution of barium, its bioaccumulation, and potential and proven health impacts (in animal models and humans) to provide the information that can be used for optimization of future experimental and epidemiological studies and developing of mitigative and preventive strategies to minimize negative health effects in exposed populations. The potential health effects of barium exposure are largely based on animal studies, while epidemiological data for humans, specifically for chronic low-level exposures, are sparse. The reported health effects include cardiovascular and kidney diseases, metabolic, neurological, and mental disorders. Age, race, dietary patterns, behavioral risks (e.g., smoking), use of medications (those that interfere with absorbed barium in human organism), and specific physiological status (e.g., pregnancy) can modify barium effects on human health. Identifying, evaluating, and predicting the health effects of chronic low-level and moderate-level barium exposures in humans is challenging: Future research is needed to develop an understanding of barium bioaccumulation in order to mitigate its potential health impacts in various exposured populations. Further, while occupationally exposed at-risk populations exist, it is also important to identify potentially vulnerable subgroups among non-occupationally exposed populations (e.g., elderly, pregnant women, children) who are at higher risk of barium exposure from drinking water and food.     

Tenure diversity and dependent causation in the effects of regional integration on land use: evaluating the evolutionary theory of land rights in Acre,Brazil

In the complex causation behind land change, dependent causation can play a central role. A case in point concerns land tenure diversity, where contrasting use rules for different lands may affect the impacts of other drivers on land use outcomes. We therefore evaluate the evolutionary theory of land rights (ETLR), which assumes homogeneous private property rights, in order to test for dependent causation due to distinct use rules among various types of private lands. In the present analysis, we focus on whether land tenure type modifies the effects of highway infrastructure on key outcomes highlighted in the ETLR framework. We take up the case of rural settlements along the Inter-Oceanic Highway in the eastern part of the Brazilian state of Acre, where there is considerable land tenure diversity. Findings from multivariate models for land titling, the castanha nut harvest, and cattle pasture all indicate that the effects of infrastructure depend on land tenure type. These results confirm the importance of dependent causation behind land use and bear implications for theory on land change, infrastructure impacts, and land system science.     

The social consequences of a natural/technological disaster: evidence from Louisiana and Mississippi

Disaster scholarship shows that people’s relationships stay the same or improve after natural disasters and become worse after technological, or human-induced, events. Using the case of Katrina, this research explores what happens to people’s relationships after a disaster that began with a catastrophic natural event and was followed by numerous failures in the way human institutions responded to the event. Through an analysis of survey data collected in devastated areas of Louisiana and Mississippi in 2008, this study tests how consequences of both natural (damage to the home and having to leave the home) and technological events (distrust in government, stress, concern about toxic exposure, and pursuing litigation) affect people’s relationships with family members and community groups. Damage to the home, distrust in government, and the pursuit of litigation lead to declines in people’s relationships. These experiences are more likely to change intimate relationships (with family) than relationships in the broader community. The relevance that these findings have for creating better social justice outcomes after future disasters is discussed.