Chikungunya antibodies detected in non-human primates and rats in three Indian Ocean islands after the 2006 ChikV outbreak

The role of terrestrial vertebrates in the epidemiology of chikungunya disease is poorly understood. We evaluated their exposure and amplification role during the 2006 chikungunya outbreak in the Indian Ocean. Blood samples were collected from 18 mammalian and reptile species from Reunion Island, Mauritius and Mayotte. Among the 1051 samples serologically tested for chikungunya virus (CHIKV), two crab-eating macaques (Macaca fascicularis) and two ship rats (Rattus rattus) proved to be exposed to CHIKV. CHIKV RNA was not detected in 791 analyzed sera. Our results confirm the preferential infection of simian primates and suggest that other vertebrates played a poor or no role in CHIKV transmission during the 2006 outbreak.     

渐近模型在优化花生种植密度上的应用

种植密度是影响作物生产效率的关键因素之一，因此将渐近模型（方程1）应用到阿根廷的花生种植密度决策中，试验采用2个品种（分别属于西班牙型和兰娜型），方式为3种行间距（分别为0.70m、0.50m和0.30m）和2种株间距（分别为0.06m和0.12m）的组合，株行距比值较低（介于0.1和0.4之间）。模型的适用范围取决于种植密度和相应的株行距比值。各方式的密度分别为12，17，24，28，33和56株/m^2，模型（方程1）恰当地描述了两个品种单产和密度之间的关系。由此模型我们可以得出花生最佳种植密度为25和30株/hm^2之间。再加大种植密度并不能取得更高的荚果产量和经济效益。     

Social integration of robots into groups of cockroaches to control self-organized choices

Collective behavior based on self-organization has been shown in group-living animals from insects to vertebrates. These findings have stimulated engineers to investigate approaches for the coordination of autonomous multirobot systems based on self-organization. In this experimental study, we show collective decision-making by mixed groups of cockroaches and socially integrated autonomous robots, leading to shared shelter selection. Individuals, natural or artificial, are perceived as equivalent, and the collective decision emerges from nonlinear feedbacks based on local interactions. Even when in the minority, robots can modulate the collective decision-making process and produce a global pattern not observed in their absence. These results demonstrate the possibility of using intelligent autonomous devices to study and control self-organized behavioral patterns in group-living animals.     

不同行距下两个花生品种的水分利用,生长发育和荚果产量

研究在本农艺学院开展,对每日平均气温、降水和光照均作记录。处理设六种不同株行距(0 .70×0 .12 ,0 .50×0 .12 ,0 .70×0 .06 ,0 .30×0 .12 ,0 .50×0 .06和0 .30×0 .06 m) ,对应密度是12 ,18 ,24 ,28 ,33和55株/ m2。测定0~100cm土壤样品水分含量,用于计算作物水分蒸发蒸腾量(ET)、作物光截获量(α)、土壤蒸发量(Es)、作物水分利用率( WUE)和蒸腾率(Te)。最低密度(0 .70×0 .12 m)单株生长最好,最高密度处理则导致最低的单株干物质产量,其余4个处理单株干物质产量居于二者之间。两个品种的不同间距处理同样对单株荚果饱果数、荚果和种子产量有显著影响,高密度下使其均降低,但单位面积荚果和种子产量提高,但Florman的产量要好于Colorado。种植处理显著影响作物水分蒸发蒸腾量。行距0 .30 m和0 .50 m下,两个品种都达到46和60 DAS;行距0 .70 m下,Colorado是66DAS而Florman是87DAS。两个品种的蒸腾率都受到行距的影响,两个品种的WUE都受到间距影响,0 .70 m行距下WUE最低,Colorado在0 .50 m和0 .30 m行距下,Florman在0 .30 m下WUE最高。行距对Te的影响因品种而异,Colorado在不同行距下无显著差异,而Florman的Te则随行距减少而增加。不同间距和品种对光合效率都没有很大影响(Colorado是3 .1×10-2Kcal/ha ,Florman是3 .0×10-2Kcal/ha)。     

Leptospirosis in the western Indian Ocean islands: what is known so far?

In the past decade, leptospirosis has emerged as a major zoonosis with a worldwide distribution. The disease is caused by bacteria of the genus Leptospira. The western Indian Ocean includes more than one hundred tropical or subequatorial islands where leptospirosis constitutes a major public health problem. The clinical signs of the human disease are generally similar to an influenza-like syndrome, but acute forms of the disease are reported and mortality remains significant in this region. In animals, clinical forms are mainly asymptomatic but leptospirosis reduces the fertility of livestock, resulting in economic losses. The data available about human and animal leptospirosis in the western Indian Ocean islands are diverse: human leptospirosis has been extensively studied in Reunion Island, Mayotte, and the Seychelles, whereas the human clinical disease has never been described in Madagascar, Comoros, Mauritius, or Rodrigues, mainly because of the deficiency in appropriate medical and diagnostic structures. The rat is recognized as the major reservoir host for the bacteria on all islands, but recent data from Reunion Island indicates that almost all mammals can be a source of contamination. The incidence of leptospirosis in humans is highly seasonal, and linked to the rainy season, which is favorable for the environmental maintenance and transmission of the bacteria. The epidemiology of leptospirosis is fully island-dependent, related to the number of mammalian species, the origins of the introduced mammalian species, the relationships between humans and fauna, and environmental as well as cultural and socio-economic factors.     

Tiller demography in tall fescue (Festuca arundinacea) swards as influenced by nitrogen fertilization,sowing method and grazing management

Tall fescue is an important temperate grassland species globally, but in many regions the effects of drought, heat and poor grazing management, reduce its persistence in summer. Furthermore, poor ground cover and low tiller population density (TP) in winter result in low radiation capture and thus limited potential to increase the low growth rates at that time. Knowledge of the effect of fertilization, defoliation managements and establishment methods on demography of tall fescue would help to improve sward management for better persistence and winter growth. Accordingly, an experiment was carried out in Pergamino, Argentina, to study the effects of two N‐ fertilizer levels, two grazing frequencies and two seeding row arrangements upon tall fescue TP demography. Herbage mass, tiller appearance (TA) and death rates were measured over 3 years. Seasonal fluctuations in TA and death rates determined well‐defined periods of increase and decrease in TP density. Maximum values were found at the end of winter and minimum ones at the end of spring, after the reproductive period. Nitrogen shortage and high herbage mass limited TA. Tiller death rate followed TA rate and was affected by nitrogen supply and defoliation frequency in the same way that TA was. Sowing arrangement affected tiller demography at the beginning of the experiment.