Nestmate recognition and the ontogeny of acceptability in the ant,Leptothorax curvispinosus

Summary In social insects, there is often a brief period following eclosion when workers are highly acceptable in alien nests of their own or other species. This study tested for such an acceptance period in the facultatively polygynous ant, Leptothorax curvispinosus, and compared the duration and effectiveness of this period for conspecific and heterospecific introductions. Workers that eclosed and aged for 1–70 h or 30 days in isolation were introduced into either their parental nests (n=24), alien conspecific nests (n=265), or nests of the closely related and biologically similar species, L. longispinosus (n=341). In alien conspecific nests, acceptance was maximal for workers aged 1–12 h at introduction (67.7% not attacked, 75.8% adopted) and gradually decreased until the level of nonaggression (after 60 h) and adoption (after 36 h) were not significantly different from 30-day-old workers (5.9% not attacked, 17.6% adopted). In heterospecific nests, acceptance was maximal for workers aged 1–4 h at introduction (34.8% not attacked, 37.0% adopted) but thereafter was not significantly different from 30-day-old workers (5.6% not attacked, 8.3% adopted). In their parental nests, workers were generally accepted regardless of age (4–56 h posteclosion, 95.8% not attacked, 100% adopted); a result that is consistent with previous research on older workers (38–157 days posteclosion). This study demonstrates an acceptance period that is more effective and of longer duration within than between these species but that, under uniform laboratory conditions, is often not necessary for the integration of workers into their parental colonies. Within colonies, acceptance periods might only be important during relatively brief periods in a colony's life history when eclosing workers produce genetically based nestmate recongition cues that are not already represented in the colony and must be learned by colony members (e.g., during early colony growth or following adoption of queens), or when young workers must acquire environmentally based nestmate recognition cues to achieve and maintain acceptability.     

对太平洋岛屿的全球国际水域评估:跨界、水资源短缺和沿海渔业问题

跨界、水资源短缺和渔场问题以近期完成的太平洋岛屿全球国际水域评估(GIWA)结果为基础进行了讨论.太平洋岛屿水域面积3000万km2,占全球海洋面积的大约12%,在地理、人口和发展等方面具有多样性.全球性变化,尤其是海平面上升和海面温度的提高,是最主要的跨界关注的问题,因为它影响着生活的方方面面.水资源短缺和不可持续发展的海洋渔业问题也是讨论的议题,因为这些问题在可预见的将来会主宰整个地区,在此以斐济、基里巴斯、汤加的例子加以说明.社会经济因素,例如人口快速增长、城市化、传统生活方式的解体以及现金经济的发展,加剧了环境问题.本文提出了有助于解决这些问题的政策方案.     

Conceiving a fetus for bone marrow donation: An ethical problem in prenatal diagnosis

We present a family who sought prenatal diagnosis in order to bear a healthy child to serve as an HLA–identical bone marrow donor for their son affected with Wiskott–Aldrich syndrome. They intended to abort HLA-incompatible fetuses who would have been unsuitable bone marrow donors. This case led us to conclude that prenatal diagnosis should not be used to benefit a third party or facilitate the conception or abortion of a fetus for the purpose of generating an organ for transplantation. The limits of parental autonomy and physician responsibility are discussed.     

The Dynamics of Rural Vulnerability to Global Change: The Case of southern Africa

Research on the agricultural impacts of global change frequently emphasizesthe physical and socioeconomic impacts of climate change, yet globalchanges associated with the internationalization of economic activity mayalso have significant impacts on food systems. Together, climate change andglobalization are exposing farmers to new and unfamiliar conditions.Although some farmers may be in a position to take advantage of thesechanges, many more are facing increased vulnerability, particularly in thedeveloping world. This paper considers the dynamics of agriculturalvulnerability to global change through the example of southern Africa. Wedemonstrate that the combination of global and national economic changesis altering the context under which southern African farmers cope withclimate variability and adapt to long-term change. We find that farmers whoformerly had difficulty adapting to climatic variability may become lessvulnerable to drought-related food shortages as the result of tradeliberalization. At the same time, however, removal of national credit andsubsidies may constrain or limit adaptation strategies of other farmers,leaving them more vulnerable to climate variability and change.     

Relationship of Effective to Census Size in Fluctuating Populations

Abstract: The effective size of a population (    N _e   ) rather than the census size (    N ) determines its rate of genetic drift. Knowing the ratio of effective to census size, N _e  /   N , is useful for estimating the effective size of a population from census data and for examining how different ecological factors influence effective size. Two different multigenerational ratios have been used in the literature based on either the arithmetic mean or the harmonic mean in the denominator. We clarify the interpretation and meaning of these ratios. The arithmetic mean N _e  /   N ratio compares the total number of real individuals to the long-term effective size of the population. The harmonic mean N _e  /   N ratio summarizes variation in the N _e  /   N ratio for each generation. In addition, we show that the ratio of the harmonic mean population size to the arithmetic mean population size provides a useful measure of how much fluctuation in size reduced the effective size of a population. We discuss applications of these ratios and emphasize how to use the harmonic mean N _e  /   N ratio to estimate the effective size of a population over a period of time for which census counts have been collected.     

Rapid enzyme immunoassays for the detection of carbaryl and methoprene in grains

In order for grain handlers and traders to reliably estimate residues of grain protectants in the field, antibody-based rapid tests were developed for carbaryl (1-naphthyl methylcarbamate) and methoprene [isopropyl (E,E)-(RS)-11-methoxy-3,7,11-trimethyldodeca-2,4-dienoate]. To complement the rapid analysis, a simple and rapid extraction technique was developed. In these tests, a pesticide-containing methanol extract of the grain sample and an enzyme-labeled component are added to precoated strips. After a brief incubation, the strips are washed and a substrate/chromogen for the enzyme is added. The color developed is stopped by acidification and the results are read either by eye or in a portable field photometer. The overall test time is under 20 minutes. For carbaryl, the test had a limit of detection of 4.5 ppb (1.1 ppm in grain), while the methoprene test had a limit of detection of 4 ppb (1 ppm in grain) based on the lower datum point, which is 15% inhibition, in the standard curves. Both assays can be used as a screening test for carbaryl and methoprene in animal feed grains.     

Estimation of selected physicochemical properties for methylated naphthalene compounds

Liquid aqueous solubility (S(w,L)), octanol/water partition coefficients (K(ow)), liquid vapor pressure (P(v,L)), and Henry's law constants (H(c)) were estimated for 20 methylated naphthalenes ranging from monomethyl to tetramethylnaphthalenes. Chromatographic methods were used for the estimation. Chromatographic retention measurements were conducted for 11 reference compounds and regressions were fit between the retention indices and the physicochemical properties. HPLC octadecylsilyl column with acetonitrile/water eluent was used for the estimation of S(w,L) and K(ow). Two GC columns, HP5-MS and a more hydrophobic HP-1, were tested for the estimation of P(v,L). Measured retention indices for the methylated naphthalenes were entered to the regression equations to calculate the physicochemical properties for these compounds. Literature values, where available, were used to validate the calculated values. The method accurately estimated the physicochemical properties. Estimated S(w,L) and P(v,L) decreased with the number of methyl groups. K(ow) increased with the number of methyl groups. There was no obvious relation between H(c) and the number of methyl groups. Log S(w,L) ranged from 0.885 for 1,2,5,6-tetramethylnaphthalene to 2.269 for 1-methylnaphthalene (mmol/m(3)). Log K(ow) varied from 3.89 for 1-methylnaphthalene to 4.95 for 1,2,5,6-tetramethylnaphthalene. Log P(v,L) ranged from -0.983 for 1,2,5,6-tetramethylnaphthalene to 0.789 for 2-methylnaphthalene (Pa). Log H(c) varied from 1.03 for 1,4,5-trimethylnaphthalene to 1.73 for 2,6-dimethylnaphthalene (Pa m(3)/mol). There were no apparent effects of GC column hydrophobicity on the accuracy of the results. Estimation of S(w,L) and K(ow) based on GC retention indices was not as accurate as with HPLC. Comparison of the estimated values with values predicted by EPIWIN indicated that EPIWIN is useful in giving order-of-magnitude prediction of physicochemical properties.     

Exposure to heavy metals and infectious disease mortality in harbour porpoises from England and Wales

We investigate whether long-term exposure to heavy metals, including immunosuppressive metals like mercury (Hg), is associated with infectious disease in a wild cetacean. Post-mortem investigations on 86 harbour porpoises, Phocoena phocoena, found dead along the coasts of England and Wales revealed that 49 of the porpoises were healthy when they died as a consequence of physical trauma (most frequently entrapment in fishing gear). In contrast, 37 porpoises died of infectious diseases caused by parasitic, bacterial, fungal and viral pathogens (most frequently pneumonia caused by lungworm and bacterial infections). We found that mean liver concentrations of Hg, selenium (Se), the Hg:Se molar ratio, and zinc (Zn) were significantly higher in the propoises that died of infectious disease compared to healthy porpoises that died from physical trauma. Liver concentrations of lead (Pb), cadmium (Cd), copper (Cu) and chromium (Cr) did not differ between the two groups. Hg, Se, and the Hg:Se molar ratio were also positively correlated with age. The association between Zn concentration and disease status may result from Zn redistribution in response to infection. Further work is required to evaluate whether chronic exposure to Hg may have presented a toxic challenge to the porpoises that succumbed to infectious disease.     

Copper tolerance,uptake and accumulation by Phragmites australis

Copper (Cu) uptake and accumulation of five populations of Phragmites australis growing in two mine sites (Parys Mountain, Wales, UK and Plombières, Belgium) contaminated with Cu and three 'clean' sites (Felixstowe, UK; Wisbech, UK and Mai Po, Hong Kong) were studied under field and glasshouse conditions. Cu tolerances in these populations of seedlings raised from seeds collected from the above five sites were also studied under glasshouse conditions. Although concentrations of Cu in the plant tissues (leaves, stems, rhizomes and roots) of P. australis and the associated soils from the Cu-contaminated sites were significantly higher than those of the plant tissues and the soils collected in the clean sites, small differences were found between the two Cu-contaminated populations and the three clean populations when seedlings were grown in 0.1 and 0.5 microg ml(-1) Cu treatment solutions. In general, different populations of seedlings showed similar growth responses, metal uptake and indices of Cu tolerance when cultured in the same Cu treatment solution for 3 weeks. There was insufficient evidence to support the hypothesis that the Cu-contaminated populations have evolved to Cu-tolerant ecotypes.     

Evaluation of approaches for terrestrial hazard classification

Hazard assessment is an essential element in the evaluation of the potential effects of chemical substances on the environment. To date, most work has focused on hazard assessment schemes for the aquatic environment, but in recent years, a number of proposals have been developed for other environmental compartments. Due to limited datasets, the suitability of the toxicity cut-off values in these schemes has not been fully determined and the practicalities associated with using these approaches have not been fully established. This study, which focused on the soil compartment, was performed to examine cut-off values proposed by two terrestrial hazard assessment schemes and establish the availability of data. Data on earthworms indicated that current proposals for toxicity cut-off values are appropriate. However, analysis of IUCLID (International Uniform ChemicaL Information Database) indicates that even for commonly used high production volume chemicals, insufficient data are available to enable classification. Whilst the necessary data may already be available for selected groups of substances (e.g. pesticides and veterinary medicines), a significant experimental testing programme would therefore be required before a terrestrial classification system could be applied widely. Such data may become available in the future as a result of initiatives such as REACH.