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111.
Investigations were carried out during the period 1997-1999 on lepidopteran entomofauna deleterious to poplars (Populus spp.) in Bulgaria. The phytophages were collected in larval and pupal stage and were reared under laboratory con-ditions to the adult stage. In two regions of Bulgaria, Sofia and Montana, 18 new and little-known phytophages in seven families were established on the trees in Populus genus: Limenitis populi (L.) (Nymphalidae); Anacampsis populefia (Cl.), Gelechia turpella (Den. & Schiff.) (Gelechiidae); Synanthedon melliniformis (Lasp.) (Sesiidae); Euproctis similis (Fuessl.) (Lymantriidae); Drymonia velitaris (Hufn.), Notodonta tritophus (Den. & Schiff.) (Notodontidae); Amphipyra pyramidea (L.), Catocala nupta (L.), Cosmia trapezina (L.), Enargia paleacea (Esp.), Eupsilia transversa (Hufn.), Ipomorpha subtusa (Den. & Schiff.), Parastichtis ypsilon (Den. & Schiff.), Scoliopteryx libatrix (L.) (Noctuidae); Gastropacha quercifolia (L.), Phyllodesma tremulifolia (Hb.) and Poecilocampa populi (L.) (Lasiocampidae). G. turpella and S. melliniformis are new records for Bulgaria and D. velitaris was found for the first time in Northern Bulgaria. Thirteen species (L. populi, E. similis, D. velltaris, N. tritophus, A. pyramidea, C. nupta, C. trapezina, E. transversa, I. subtusa, P. ypsilon, G. quercifolia, P. tremulifolia and P. populi) were established for the first time in Bulgaria to have a trophic relationship with poplars. G. turpella and L subtusa were occurred in the highest population densities – up to 1.6 larvae/m and up to 1.1 larvae/m respectively. The remaining species occurred in low population densities in the studied habitats and were not considered to be pests on the poplars.  相似文献   
112.
While the significant ecosystem damage caused by invasive weeds has been well documented, the economic consequences of specific invasive weed species are poorly understood. Yellow starthistle (Centaurea solstitialis L., hereafter YST) is the most widespread noncrop weed in California, resulting in serious damage to forage on natural range and improved pasture. A survey was administered to California cattle ranchers to investigate YST infestation rates, loss of forage quantity and value, and control or eradication efforts. The results were used to estimate countywide losses and costs for 3 focus counties, as well as statewide losses/costs, due to YST in California. Total losses of livestock forage value due to YST on private land for the state of California are estimated at $7.65 million per year, with ranchers' out-of-pocket expenditures on YST control amounting to $9.45 million per year. Together, these amount to the equivalent of 6%–7% of the total annual harvested pasture value for the state. Therefore, while the impacts are relatively small within the statewide total agricultural production system, losses and costs due to YST infestation do constrain California's livestock grazing sector.  相似文献   
113.
Animals need sufficient space to ensure physical health and to permit the performance of important behaviors. The effects of spatial restriction will increase with duration of confinement. In addition, diurnal rhythms are relevant. Animals may often require only sufficient space to rest comfortably but, at certain periods, additional space will be required for the performance of comfort, foraging, social or exploratory behavior. The spatial needs of unassuming animals such as chickens and rodents have been assessed using many approaches. First, animals can be housed at relevant allowances and a broad range of measures of health, behavior, physiological status and immune function taken to assess overall welfare. Second, the behavior of animals can be observed after spatial restriction is removed. A significant rebound in behavior performance would indicate that this behavior was being prevented by confinement. Third, the strength of animals' choices for additional space can be examined. Evidence from all three approaches showed that the extreme spatial confinement experienced by laying hens in conventional battery cages resulted in poor welfare, helping to secure a phase-out of conventional cages in Europe by 2012. It has been more difficult to establish optimum space allowances for species kept under less extreme restriction, such as laboratory mice and rats. No consistent effects on welfare were found when inbred and outbred mice were housed at 60, 100 or 167 cm2/mouse. In contrast, sleep disruption was increased when young rats housed were housed at higher stocking densities. Finally, assessment of optimum spatial allowance (stocking density) for animals housed in large groups, is complicated by complex interactions between enclosure size and group number.  相似文献   
114.
Five Colletotrichum lindemuthianum populations causing anthracnose in common bean, a premier legume crop of Himachal Pradesh were analyzed to know about genetic diversity, migration and the probable rate of spread of races capable of overcoming resistance present in elite cultivars. The genetic diversity was calculated on the basis of allele frequencies of 12 random amplified polymorphic DNA markers using Nei's genetic diversity formulae. Diversity within each population (HS) was high with values ranging from 0.26 to 0.31. Average differentiation among populations (GST) was 0.12 and populations were isolated by distance between the two populations. This indicates that less short distance gene flow occurs in Himachal Pradesh. However, the topography of Himachal Pradesh could be a barrier to long distance dispersal. Normalized haplotype diversity based on RAPD data was very high with mean value of 0.91. Keeping this in view, new races would be expected soon outside the state of origin, as naturally occurring gene flow is likely to be increased by the human activity for comprehensive cultivation of beans in the near future. Therefore, it is difficult to predict durability of resistant sources in Himachal Pradesh, which in turn emphasizes identification and introgression of R genes into commercial cultivars.  相似文献   
115.
青藏高原草地退化原因述评   总被引:23,自引:11,他引:23  
导致青藏高原草地退化的因子很多,主要有气候、野生动物和人类活动等。在气候因素中以气温和降水的影响为主,短期内气候的变化不会成为草地退化的主导因素,从长期来看,气候变化与草地退化之间的相互作用可引起草地生态系统的退化;野生动物因素中主要以植食性小哺乳动物的影响为主,其危害程度取决于其种群数量的高低,同时大型野生草食动物对草地退化的影响也不容忽视;人类活动因素中主要以家畜过度放牧为主,在一定程度上,家畜放牧强度的高低直接决定草地的退化程度;草地退化是多种因素综合作用的结果。不同地区导致草地退化的主要因素不尽相同,导致青藏高原草地退化最主要的因子是过度放牧和植食性小哺乳动物种群爆发。针对退化的原因,提出了青藏高原退化草地恢复与管理过程中应注意的事项。  相似文献   
116.
Objective To determine the extent of the snake bite problem in domestic animals, its regional significance and the effects of antivenom treatment.
Design A questionnaire was designed seeking information on the number and type of domestic animals referred, whether treated or untreated, type of snakes and management of the bite.
Procedure The survey form was sent to 10% of veterinary surgeons, selected at random throughout Australia.
Results The response of 106 veterinary surgeons revealed that snake bite in domestic animals is frequent, with an estimated 6200 cases reported annually. Bites were more prominent in rural (78%) than urban areas (22%) with brown, tiger and black snakes accounting for 76%, 13% and 6% of cases, respectively. Cats and dogs were the most frequently reported victims. Ninety-one percent of cats and 75% of dogs survived following the administration of antivenom whereas 66% of cats and 31% of dogs survived without antivenom. Overall, in 33% of cases antivenom was not used, and venom detection kits were used in only 1% of cases. A number of drugs were used in various combinations with or without antivenom and intravenous fluids in the treatment of animals with snake bite, but their role in reducing the severity of envenomations was not assessed.
Clinical implications Antivenom significantly improves the chances of survival of domestic animals bitten by snakes.  相似文献   
117.
为了解野生树鼩的寄生虫感染状况,剖检昆明市西郊野外捕获的3只树鼩(雄性1只、雌性2只)后进行寄生虫检查。结果显示,雌性树鼩的体表和体内均未检出寄生虫,在雄性树鼩的肠道发现严重绦虫感染,共检出虫体16条,经鉴定为长膜壳绦虫(Hymenolepis diminuta),绦虫总重量为3.4 g,占该树鼩体重的3.6%。  相似文献   
118.
There is a clear need to monitor the health of wildlife in the UK, to help to understand the population dynamics of endangered species and to detect any harm to the welfare of wild animals caused by human beings. Despite previous proposals, there has been little progress in the development of a national programme of monitoring. With notable exceptions, the current schemes for investigating the morbidity and mortality of wild animals cover only limited groups of animals and are fragmented and uncoordinated. They consist of statutory schemes of restricted scope, and studies in universities, institutes and wildlife rehabilitation centres with limited funding. As a result, significant disease incidents may remain undetected and others may not be investigated fully, posing risks to the welfare and conservation of wildlife, the welfare of domestic animals, and in some cases to human health. Coordinated national schemes for the surveillance of the health of wildlife are already established in France, the USA and Canada and their best characteristics could be used to develop a scheme for the UK.  相似文献   
119.
Facultative paedomorphosis, a process in which newt larvae can opt for reproduction before or after metamorphosis, is geographically heterogeneous. Despite numerous ecological studies and recent evidence of declines in paedomorphic populations, however, no attempt to model environmental variables that explain the presence of paedomorphs has been made at a multi-scale level. Our aim was to fill this gap in studying three newt species (Lissotriton vulgaris, Mesotriton alpestris, and Triturus macedonicus) of the Montenegrin karst as model species. To this end, we used multivariate analysis on three scales of habitat: the breeding pond, the land use and the climatologic features. Results show that the study area is both an important hotspot for paedomorphosis and where intraspecific diversity is quickly disappearing (20-47% extirpation) because of fish introductions. Other habitat variables (water permanency, pH or the habitat origin) were shown to act on paedomorphosis but not consistently across species, confirming complexity of the evolutionary and ecological processes. This study appeals for more long-term and detailed landscape studies of polyphenisms, a neglected but promising topic, to better understand and protect alternative modes of development. Particularly, measures should be taken to identify hotspots of intraspecific diversity at a global scale and stop fish introductions before we reach a point of no-return.  相似文献   
120.
试验旨在研究催乳素受体(prolactin receptor,PRLR)和卵泡刺激素β(follicle-stimulating hormone β,FSHβ)基因的多态性及其与母猪繁殖性状的关联分析。采用PCR-RFLP方法对大白猪、杜洛克猪和长白猪3个猪种共487头母猪进行了PRLR和FSHβ基因多态性检验,并采用单因子方差分析、LSD法分析不同基因型与母猪总产仔数、产活仔数、断奶窝重和断奶窝仔数等繁殖性状的相关性。结果表明,PRLR基因在大白猪和长白猪中B等位基因均为优势基因,基因频率分别为0.717和0.548,大白猪BB基因型总产仔数显著高于AA基因型(P<0.05),长白猪BB基因型断奶窝重显著高于AB基因型(P<0.05);FSHβ基因在大白猪、杜洛克猪和长白猪3个猪种中B等位基因均为优势基因,基因频率分别为0.804、0.760和0.789,长白猪BB基因型总产仔数和产活仔数均显著高于AB基因型(P<0.05),呈现BB>AA>AB趋势。因此,PRLR和FSHβ基因对荣昌猪场母猪繁殖性能有一定影响,可作为母猪繁殖性能分子选育的候选参考基因。  相似文献   
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