Attraction of field-flying aphid males to synthetic sex pheromone

Summary Transparent plastic water traps, baited with the synthetic aphid sex pheromone components (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol or control lures, were placed in four semi-sheltered field sites at a height of 1.1 m. Although males of twenty-one aphid species were collected from the water traps, onlySitobion fragariae (Walker) was abundant. In total, 8 pheromone traps produced 102 males compared with only 10 males in 8 control traps. The sex pheromone released by sexual femaleS. fragariae was identified as the nepetalactone used in the lures. Aphid sex pheromones may be more species-specific than previously thought and the presence of a host plant is not essential for males to locate sexual females.     

Role of esters in egg removal behaviour in honeybee (Apis mellifera) colonies

In queen-right honeybee colonies workers detect and eat the vast majority of worker-laid eggs, a behaviour known as worker policing. However, if a colony becomes permanently queen-less then up to 25% of the worker population develops their ovaries and lay eggs, which are normally reared into a final batch of males. Ovary development in workers is accompanied by changes in the chemical secretion of the Dufour's gland with the production of queen-like esters. We show that ester production increases with the period that the colony is queen-less. The increased ester production also corresponds to an increase in persistence of worker-laid eggs in queen-right colonies, since the esters somehow mask the eggs true identity. However, in a rare queen-less colony phenotype, workers always eat eggs indiscriminately. We found that the egg-laying workers in these colonies were unusual in that they were unable to produce esters. This apparently maladaptive egg eating behaviour is also seen in queen-less colonies prior to the appearance of egg-laying workers, a period when esters are also absent. However, the indiscriminate egg eating behaviour stops with the appearance of ester-producing egg-laying workers. These observations suggest that esters are providing some contextual information, which affects the egg eating behaviour of the workers.     

Long-term tillage effects on soil metolachlor sorption and desorption behavior

Sorption and desorption are two important processes that influence the amount of pesticides retained by soils. However, the detailed sorption mechanisms as influenced by soil tillage management are unclear. This study examined the sorption and desorption characteristics of metolachlor [2-chloro-N-(2-ethyl-6-methyphenyl)-N-(2-methoxy-1-methylethyl)-acetamide] using the soil samples collected from the long-term conservation tillage (CnT) and conventional tillage (CT) research plots established in 1979 in Darlinton, SC. Humic acid (HA) and humin were extracted from the soils and used in the sorption experiments along with the whole soil samples. The sorption experiments were conducted using a batch-equilibration method. Three sequential desorption rinses were carried out following the sorption experiments. By comparing metolachlor sorption and desorption results we observed hysteresis for all soil samples and their organic matter fractions. Sorption nonlinearity (N) and hysteresis were dependent on the structure and composition of soil organic matter (SOM), e.g., Freundlich isotherm exponents (N) of HA and humin from CnT were higher than those of CT treatment, which may be related to high aromaticity of SOM fractions in CT treatment. Sorption capacity (K'f) was positively correlated with soil organic carbon (SOC) content. These results show that long-term tillage management can greatly affect metolachlor sorption and desorption behavior probably by qualitative differences in the structural characteristics of the humic substances.     

Effects of changes in climate on landscape and regional processes, and feedbacks to the climate system

Biological and physical processes in the Arctic system operate at various temporal and spatial scales to impact large-scale feedbacks and interactions with the earth system. There are four main potential feedback mechanisms between the impacts of climate change on the Arctic and the global climate system: albedo, greenhouse gas emissions or uptake by ecosystems, greenhouse gas emissions from methane hydrates, and increased freshwater fluxes that could affect the thermohaline circulation. All these feedbacks are controlled to some extent by changes in ecosystem distribution and character and particularly by large-scale movement of vegetation zones. Indications from a few, full annual measurements of CO2 fluxes are that currently the source areas exceed sink areas in geographical distribution. The little available information on CH4 sources indicates that emissions at the landscape level are of great importance for the total greenhouse balance of the circumpolar North. Energy and water balances of Arctic landscapes are also important feedback mechanisms in a changing climate. Increasing density and spatial expansion of vegetation will cause a lowering of the albedo and more energy to be absorbed on the ground. This effect is likely to exceed the negative feedback of increased C sequestration in greater primary productivity resulting from the displacements of areas of polar desert by tundra, and areas of tundra by forest. The degradation of permafrost has complex consequences for trace gas dynamics. In areas of discontinuous permafrost, warming, will lead to a complete loss of the permafrost. Depending on local hydrological conditions this may in turn lead to a wetting or drying of the environment with subsequent implications for greenhouse gas fluxes. Overall, the complex interactions between processes contributing to feedbacks, variability over time and space in these processes, and insufficient data have generated considerable uncertainties in estimating the net effects of climate change on terrestrial feedbacks to the climate system. This uncertainty applies to magnitude, and even direction of some of the feedbacks.     

Early prenatal sonographic appearance of rare thoraco-abdominal eventration

Fetal ventral wall malformations may be diagnosed prenatally with ultrasound. These include omphalocele, gastroschisis, or even thoracic defects with or without ectopia cordis. It is important whenever such a defect is found to carefully define the full extent of the lesion prior to parental counselling. Described and illustrated here is the prenatal diagnosis with real-time ultrasound at 17 weeks gestation of a rare thoraco-abdominal ventral wall defect including omphalocele, bifid sternum, diaphragmatic aplasia, and pericardial aplasia with incomplete ectopia cordis. The technique is described and the importance of the complete, accurate delineation of anatomic malformations is emphasized.     

Comparison of beach bacterial water quality indicator measurement methods

Three methods (membrane filtration, multiple tube fermentation, and chromogenic substrate technology kits manufactured by IDEXX Laboratories, Inc.) are routinely used to measure indicator bacteria for beach water quality. To assess comparability of these methods, quantify within-laboratory variability for each method, and place that variability into context of variability among laboratories using the same method, 22 southern California laboratories participated in a series of intercalibration exercises. Each laboratory processed three to five replicates from thirteen samples, with total coliforms, fecal coliforms or enterococci measured depending on the sample. Results were generally comparable among methods, though membrane filtration appeared to underestimate the other two methods for fecal coliforms, possibly due to clumping. Variability was greatest for the multiple tube fermentation method. For all three methods, within laboratory variability was greater than among laboratories variability.     

An Assessment of People's Satisfaction with the Public Hearing on the Yadana Natural Gas Pipeline Project

Many public and large-scale construction projects inThailand have been faced with environmental and socialconflict problems. The major cause is that project sponsorsdo not address concerns of the public in a proper mannerduring EIA study. The Yadana Natural Gas Pipeline (YNGP)project is an example of a project which suffered theeffects of public demonstration. A public hearing, onetechnique of public participation, is a good mechanism tosolve conflict problems in a non-violent way which the ThaiGovernment usually adopts to settle conflict in constructionprojects. In the case of the YNGP, even after the conflictwas resolved hostility towards the project was noteliminated, as the opponents were not satisfied with thedecision. Therefore, this article examines the hearing on theYNGP project. The study found that it was too late to make any significantchanges to the project after the hearing was held, mostrespondents were not satisfied with the project. In otherwords, this hearing did not improve their perception ofenvironmental soundness of the project. The study showedthat the project's impact on the environment was notproperly addressed. The project sponsors did not providesufficient publicity for the meeting and the stage at whichthe hearing was conducted. Suggestions are made forimproving participation in future hearings.     

Environmental Contaminants in Blood, Hair, and Tissues of Ocelots from the Lower Rio Grande Valley, Texas, 1986–1997

The ocelot (Felis pardalis) isan endangered neotropical cat distributed within asmall range in the Lower Rio Grande Valley (LRGV), inTexas, U.S.A. Studies of the impacts of environmentalcontaminants in wild cats are few. Approximately onefourth of the estimated population (about 100) ofocelots in the LRGV was sampled to evaluate theimpacts of chlorinated pesticides, polychlorinatedbiphenyls, and trace elements on the population. Hairwas collected from 32 ocelots trapped between 1986–1992,and blood was collected from 20 ocelots trappedbetween 1993–1997. A few blood samples were obtainedfrom individuals recaptured two or three times. Tissue samples from 4 road-killed ocelots were alsoanalyzed. DDE, PCBs, and Hg were some of the mostcommon contaminants detected in hair and blood. MeanHg levels in hair ranged from 0.5 to 1.25 g g^-1 dw,Se from 1.5 to 3.48 g g^-1 dw, and Pb from 0.56 to26.8 g g^-1 dw. Mean DDE concentrations in plasma ranged from 0.005 g g^-1 ww to 0.153 g g^-1 ww, and PCBs ranged from 0.006 g g^-1 ww to 0.092 g g^-1 ww. Mean Hg levels in red blood cells rangedfrom 0.056 g g^-1 dw to 0.25 g g^-1 dw. Concentrations of DDE, PCBs, or Hg, did not increasesignificantly with age, although the highestconcentrations of DDE and Hg were found in olderanimals. Overall, concentrations of DDE, PCBs, and Hgwere low and at levels that currently do not pose anythreat to health or survival of the ocelot. This isfurther supported by good reproduction of the ocelotin the LRGV, where adult females averaged about 1.5kittens/litter. Thus, it seems that the current majorthreat to recovery of the ocelot in the LRGV may behabitat loss, although potential impacts of newgeneration pesticides, such as organophosphorus andcarbamate insecticides need further study.     

Variability in the identification and enumeration of marine benthic invertebrate samples and its effect on benthic assessment measures

Studies designed to measure anthropogenic impacts on marine benthic communities depend on the ability of taxonomists to consistently discriminate, identify, and count benthic organisms. To quantify errors and discrepancies in identification and enumeration, 20 samples were completely reprocessed by another one of four participating laboratories. Errors were detected in 13.0% of the data records, affecting total abundance by 2.1%, numbers of taxa by 3.4%, and identification accuracy by 4.7%. Paired t-tests were used to test for differences in the Benthic Response Index (BRI), total abundance, numbers of taxa, and the Shannon-Wiener index between the original and the reanalysis data. Differences in the BRI were statistically insignificant. Although statistically significant differences were observed for numbers of taxa, total abundance, and the Shannon-Wiener index, the differences were small in comparison to the magnitude of differences typically observed between anthropogenically affected and reference sites.