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951.
小菜蛾抗性稳定性及抗性治理对策研究   总被引:9,自引:1,他引:9  
试验表明,福州地区田间小菜蛾已对有机磷、氨基甲酸酯及拟除虫菊酯产 生高抗性。脱离选择压力3代后,小菜蛾的抗性水平迅速下降。Bt预处理可提高抗性和敏感小菜蛾幼虫 对有机磷的敏感性,尤其对抗性小菜蛾增效极显著,对敏感小菜蛾AChE的 Ki值则影响不 大。据此提出在抗性治理中,应轮用或换用不同毒理机制的杀虫剂,且其间隔至少为2~3代。  相似文献   
952.
稻秆潜蝇是浙南山区水稻生产的重要害虫.通过推广薄膜育秧、绿肥田除草、选用抗性品种、实行健身栽培、生态控制等一系列综合防治技术,可达到经济有效的防治效果.在水稻整个生长期可减少用药1~2次,稻秆潜蝇穗被害率减轻41.03%,病虫害损失控制在3.6%以内,稻谷增产9.2%,稻田害虫天敌蜘蛛和黑肩绿盲蝽分别增加38.1%和26.3%,获得了明显的生态、经济效益.  相似文献   
953.
The efficacy of oxolinic acid (at 200 and 300 μg a.i./l) and of several antibiotic compounds (streptomycin sulfate at 100 μg a.i./l, glycocide B at 700 μg a.i./l, kasugamycin at 80 μg a.i./l and gentamicin sulfate at 30 and 60 μg a.i./l) againstErwinia amylovora, the causal agent of fire blight in pears, was evaluated in 43 orchard experiments in 1997–2000 in Israel. In addition to the above orchard experiments, the efficacy of the bactericides was tested in live experiments with artificial inoculation. Natural fire blight symptoms were observed in 16 of the 43 experiments; in 13 of them, disease intensity and its distribution among the experimental plots provided a basis for data analysis, leading to reliable conclusions concerning the efficacy of the tested bactericides. Oxolinic acid at 300 μg a.i./l was highly effective againstE. amylovora and reduced disease severity significantly in all experiments, as compared with the untreated plots; however, a concentration of 200 μg a.i./l was not effective in some cases. Among the tested antibiotics, only gentamicin sulfate was as effective as oxolinic acid. Results of the artificial inoculation experiments corroborated those obtained in the naturally infected orchards. The pre-infection activity of oxolinic acid was determined on blossom clusters that were sprayed with the bactericide before inoculation. Control efficacy on blossom clusters sprayed 1–4 days before inoculation ranged from 68% to 80%, a level which did not differ significantly from that observed on blossom clusters sprayed on the day of inoculation (80% control). The postinfection activity of oxolinic acid was determined on blossom clusters that were sprayed with the compound after inoculation. Oxolinic acid was as effective when applied 1 or 2 days after inoculation as when it was applied on the day of inoculation; however, application of the bactericide 3 days after inoculation no longer resulted in significant disease suppression. Oxolinic acid has been used commercially in Israel since 1998 with appreciable success. Contribution No. 533-00 from the Agricultural Research Organization  相似文献   
954.
美洲斑潜蝇: 一种国际上重要的检疫害虫   总被引:7,自引:0,他引:7  
根据文献报道,本文对美洲斑潜蝇的分布,寄主,为害特征,生物学特性,主要寄生性天敌以及防治等问题进行了综合性的介绍,该虫的分类特征也作了详细的描述  相似文献   
955.
The ecological implications of insect resistance in conifers are rarely discussed. It is however a fairly straightforward plant-insect interaction and should be treated as such, making use of the increasing amount of information in this field. Work on tree breeding is usually carried out by silviculturalists who, not surprisingly, rarely consider the insect component of the environment in which the treess are growing. In all fairness, it must be stated that many entomologists, fail to consider the plant component of the interaction. Clonal forestry will almost certainly result in the loss of genetic variability. The use of clonal material has already been cited as a possible source for the diminution of the resistance against pests and diseases and if particular resistance mechanisms against forest pests are sought in the future the reduction in genetic material caused by clonal selection could have serious consequences. The ethics of clonal forestry have been questioned as have the ethics of biotechnological advances in the area of recombinant DNA molecules. The potential of both these techniques should be publicized and brought to the attention of the general public and the scientific community at large and evaluated. To improve our forest environment and to protect the environment as a whole, entomologists, geneticists, physiologists and silviculturalists must work together to produce better trees that require little, if any, chemical aid, be it insecticides, herbicides, fungicides or fertilizers. An increasing awareness of the environmental problems generated by large-scale insecticide applications to forest plantations, coupled with an increasingly chemophobic work-force and the difficulty in obtaining pesticide registration for use in forest environments, means that the forest industry world-wide must look to the use of integrated control measures with more diligence than has been shown in the past. Many recent outbreaks of pests and diseases have been linked with particular seed origins of tree crops. Host plant resistance as part of a suite of other proposed integrated control tools is thus an obvious candidate for development. Despite this, scientists concerned with tree improvement continue to select largely for silvicultural traits rather than for resistance to pests and disease. The different avenues open to plant breeders are examined and the potential of breeding trees resistant to insect attack highlighted. Using resistant trees as part of an integrated pest management system has five very important properties. Firstly, there is no additional pest control cost to the grower, secondly, it operates at all levels of insect incidence and not just when the pest is at high population levels, thirdly, it reduces the insect population cumulatively, fourthly it avoids toxic residues and environmental pollution and, finally, it usually interacts well with the other integrated pest management strategies in existence.  相似文献   
956.
瓢虫柄腹姬小蜂在南昌室内,5月下旬至12月上旬可繁殖11代,每代需12~46天。该蜂的发育起点温度为5.28℃。有效积温296.85日度。在28℃下,饲以10%蜂蜜,成蜂平均寿命为5.52天,不喂蜂蜜平均约缩短3天。该蜂能寄生28星瓢虫幼虫的各个龄期,但更喜寄生高龄幼虫,以4龄幼虫作寄主,每雌一生能寄生幼虫6.21头,子蜂数平均为74.57头。可行孤雌生殖产雄。在马铃薯上的自然寄生率以6月份最高,平均为28.47%。在龙葵上以7月份最高平均达64.5%。7月中旬由于高温的影响,寄主和寄生蜂的发育受到抑制,寄生率急剧下降。  相似文献   
957.
宁夏盐池县沙边子试验基地生态效益评价   总被引:4,自引:0,他引:4  
陈功 《干旱区研究》1993,10(4):49-53
本文简要总结了沙边子试验基地九年来所做的主要工作,同时试用模糊数学方法采用三类评价指标17个评价因子对基地整治前(1982年)和整治后(1990年)的生态效益给予综合对比评价。  相似文献   
958.
昆虫病原斯氏和异小杆线虫人工大量培养的研究概况   总被引:3,自引:0,他引:3  
韩日畴 《昆虫天敌》1993,15(4):183-193
昆虫病原斯氏和异小杆线虫的大面积田间应用要求线虫有效地生产,本文介绍业已建立线虫大量培养方法及合适于大规模生产线虫的工厂化培养系统及有关的技术参数,并讨论其优化管理问题。  相似文献   
959.
A case study of forest change in the Swiss lowlands   总被引:2,自引:0,他引:2  
Bürgi  Matthias 《Landscape Ecology》1999,14(6):567-576
This paper presents a regional case study of forest development and the history of forest use and management in the north-eastern lowlands of Switzerland during the 19th and 20th centuries. The analysis draws on historical documents related to forestry to consider the following aspects of forest change: forest types, growing stock, trees species composition and non-timber forest uses. Based on the data presented, three overlapping periods of forest use and management can be discerned. The period of traditional multiple use lasted until the second half of the 19th century. From the mid 19th to the mid 20th century, a period of primacy of timber production occurred. During the 20th century, the period of modern multi-impact management has developed. For these three periods, groups of main actors, their needs and interests, and how they were causing the changes in the aspects under study were defined. This procedure of defining periods and the respective groups of main actors is a critical link between landscape ecology and history, as changes in demands of the society can be directly linked with changes in land-use and land-cover.  相似文献   
960.
The central and regional organisation of the campaign to eradicate the CSF epidemic in the Netherlands in 1997/1998 is described. The main instruments used in the campaign were based on stamping-out and movement restrictions specified by the European Union. Additional instruments were used for the first time, namely, pre-emptive culling of contact and neighbouring farms, compartmentalisation of transport, monthly serological screening in established surveillance areas and supervised repopulation of all farms in the former surveillance zone. Two other measures, the killing of very young piglets and a breeding ban were introduced to reduce production in established surveillance zones. Several factors complicated the eradication campaign, for instance, the late detection of the first infection; artificial insemination as a source of infection; the organisation of pig farming in the Netherlands, with its highly concentrated production and dependence on the transport of stock from one unit to another; insufficient rendering capacity; decreasing sensitivity of clinical inspection; and extremely high costs.  相似文献   
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