The application of reproductive technology to endangered species breeding programmes

Captive breeding plays an increasingly important role in species conservation, but special problems are encountered in achieving the ideal of a demographically stable but genetically diverse population. Breeding programmes involving co-operation among a number of centres are now being developed which will overcome some of these difficulties by identifying individual animals, genetic lineages or age cohorts from which to breed. Application of techniques such as artificial insemination, embryo transfer and semen collection and storage, as well as the monitoring of reproductive status will contribute to the success of such programmes. The usefulness of these procedures for various population problems is discussed and criteria for their appropriate implementation within breeding programmes is outlined.     

Mitochondrial DNA as a genetic marker for brown trout, Salmo trutta L., populations

Mitochondrial DNA was examined in natural and hatchery-reared stocks of brown trout, using different methods of restriction analysis. The methods included the development of a brown trout mt DNA hybridization probe through cloning part of the brown trout mitochondrial genome. In addition, fragments were analysed by ethidium bromide staining and end-labelling. The relative merits of each of these methods in assessing levels of genetic relatedness between the natural and hatchery-reared brown trout stocks were evaluated. In addition, the study revealed a diagnostic mtDNA restriction pattern which could be used as a genetic marker for the discrimination of these two groups of brown trout.     

Evaluation of the risk of overwintering Helicoverpa spp. pupae under irrigated summer crops in south-eastern Australia and the potential for area-wide management

Surveys were undertaken to determine the distribution of overwintering pupae of two species of Helicoverpa in south‐eastern Australia. The results indicate that significant populations of H. armigera have the potential to overwinter as pupae in the region under residues of their summer crop hosts. H. punctigera, conversely, was found not to overwinter in the region to any significant degree. The results also suggest that a high proportion of the overwintering H. armigera population are located in relatively few high risk fields. The overwintering population represents an ideal opportunity for control on an area‐wide basis using post harvest cultivation or “pupae busting”. The risk of overwintering H. armigera pupae occurring was largely associated with crop type, the mechanism being related to the date that the crop flowers, the level of pupal parasitism and the use of larval control measures. The results are discussed in terms of recommendations for farmers and it is suggested that a concerted effort to cultivate high risk fields has the potential to significantly reduce the population on an area‐wide basis.     

Factors influencing the effectiveness of an attracticide formulation against the Oriental fruit moth, Grapholita molesta

An attracticide formulation, LastCall?OFM, was tested against the Oriental fruit moth Grapholita molesta (Busck) (Lepidoptera: Tortricidae) in replicated small plot field trials in apple, Malus domestica (Borkhausen), orchards in South‐eastern Pennsylvania, USA. Attracticide treatments were applied using a calibrated hand pump, and treated plots were compared to similar untreated plots. Male moth activity was monitored using virgin female‐baited traps, and the potential for reduction in mating activity was assessed using sentinel virgin females. A comparison of application rates showed that 1500 droplets per ha of the attracticide formulation was as effective as 3000 droplets per ha, and both application rates reduced captures in synthetic pheromone‐baited traps for prolonged periods. Droplets placed either at high or low positions within the canopy significantly reduced trap capture and mating with sentinel females. In addition, the only sentinel females that mated in the treated plots were located in the untreated portion of the tree canopy. Mate finding behaviour was equally disrupted by formulations with and without insecticide. Therefore, under the test conditions, the mechanism by which the attracticide formulation worked was by disruption of male orientation, and not by the removal of males due to insecticide poisoning. Two field cage experiments tested the impact of population density on the competitiveness of the attracticide formulation compared to virgin females. A significant proportion of males were captured in female‐baited traps at the highest female‐to‐droplet ratio tested. Equal proportions of males were captured in attracticide‐baited traps at male moth densities of 10, 20, 40, and 80 males per cage. These results clarify some of the factors influencing the effectiveness and possible mechanisms of an attracticide management tactic against the Oriental fruit moth.     

The importance of ecological research for ecosystem management: The case of browsing by swamp wallabies (Wallabia bicolor) in commercially harvested native forests

Summary Ecosystem management often proceeds within the context of sub‐optimal relationships between ecologists and ecosystem managers, and management outcomes could be improved with greater collaboration between members of these disciplines. This paper identifies an ecosystem management problem resulting from the interaction between timber harvesting and browsing wallabies, and this case study is used to exemplify how ecological data and expertise can contribute to the process of ecosystem management. It is argued that appropriate use of existing ecological data, establishment of strategic new research and the implementation of management actions as experimental hypothesis tests can facilitate achievement of management objectives, but greater collaboration between ecologists and managers is required before this can occur. Reasons for sub‐optimal relationships are outlined, and the potential for structural change within large State‐run ecosystem management agencies to improve interactions between managers and ecologists is discussed.     

DECISION TOOLS FOR MULBERRY THRIPS PSEUDODENDROTHRIPS MORI (NIWA, 1908) MANAGEMENT IN SERICULTURAL REGIONS; AN OVERVIEW

Abstract Mulberry thrips Pseudodendrothrips mori (Niwa, 1908) is a major pest of mulberry trees recorded from different sericultural regions of the world. The thrips infestation affects the qualitative and quantitative characters of mulberry leaf, by direct feeding damage to leaves and the ingestion of sap, which in turn affects the silkworm cocoon crop. This is most harmful in dry climates and seasons when heavily attacked plants lose moisture heavily. Under these conditions infestation can seriously deplete yields. The seasonal population fluctuation and the degree of damage caused to the host plant are influenced by various environmental factors including climate, host-plant variety, topography, soil type, and management regimes. This article attempts to review all available documents on mulberry thrips and to discuss the practical approaches for best control of this pest.     

玉米根微粒体ABA结合蛋白的性质及逆境胁迫的影响

以玉米根微粒体为材料进行的微量放射配体结合（ＭＲＬＢ）实验表明玉米根微粒体膜上存在着ＡＢＡ结合位点,ＡＢＡ与ＡＢＡ结合蛋白（ＡＢＡ－ＢＰ）结合的最适ｐＨ为６．５,结合反应对温度（０℃和２５℃）不太敏感,ＡＢＡ与ＡＢＡ－ＢＰ的结合反应是一个动态平衡过程,５ｍｉｎ即可达最大结合（Ｂｍａｘ）的５０％,３０ｍｉｎ达到最大结合,１ｈ内基本保持不变。胰蛋白酶处理表明此结合位点为蛋白质,冻融实验则表明此蛋白与ＡＢＡ的结合不仅要求其自身具有特定构象而且需要有一定的膜脂环境,ＤＴＴ处理实验结果显示ＡＢＡ－ＢＰ中可能存在着二硫键。逆境处理可以提高玉米根微粒体膜对ＡＢＡ的结合活性,盐胁迫、渗透胁迫、干旱胁迫和热冲激处理分别使结合活性上升３４．９％、１７．８％、２３．１％和１３．３％。     

Managing the pattern of forest harvest: lessons from wildfire

Managing forests for sustainable use requires that both the biological diversity of the forests and a viable forest industry be maintained. A current approach towards maintaining biological diversity is to pattern forest management practices after those of natural disturbance events. This paradigm hypothesizes that ecological processes will be maintained best where active management approximates natural disturbance events. The forest management model now used in most sub-boreal and boreal forests calls for regularly dispersed clearcuts no greater than 60–100 ha in size. However, the spatial characteristics of the landscape produced by this model are distinctly different from the historic pattern generated by wildfire, which was heretofore the dominant stand-replacing process in these forests. Wildfire creates a more complex landscape spatial pattern with greater range in patch size and more irregular disturbance boundaries. Individual wildfires are often over 500 ha but leave patches of unburned forest within them. The combination of these attributes is not present in recent clearcuts. Allowing a proportion of larger (i.e.>500ha) harvest units may provide distinct economic advantages that could outweight the opportunity costs of leaving some patches of forest behind. For the forest type examined, further evaluation of modelling forest harvest patterns more closely after the patterns created by wildfire is required as it may achieve a good balance and strike a suitable compromise between certain ecological and economic objectives of sustainable development.