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11.
昆虫免疫是寄主昆虫抵御寄生物侵袭的一种防卫机制。寄主昆虫常通过被囊化作用来清除不适合的拟寄生物;相应地,拟寄生物逐步建立起一系列克服寄主免疫应答的策略,包括被动的和主动的策略。  相似文献   
12.
受病原体感染后,植物会获得一种持久广泛的抗性,称为系统获得性抗性,受到昆虫侵害时也会获得类似的系统获得性抗性.植物系统抗虫与抗病信号分子不同,前者是茉莉酸(JA)、甲基茉莉酸(Me-JA)或系统素,而后者是水杨酸(SA).SA介导的系统抗病信号途径与JA等介导的系统抗虫信号途径并非完全独立,而是存在所谓的"交叉对话",但"交叉对话"结果是相互促进还是抑制仍不清楚.植物系统抗性信号及其互作研究无疑会完善植物保护策略.  相似文献   
13.
Over the last few decades, several phenomena contributed to modify the structure and composition of the eastern North American forests. Along with forest management, disturbances such as insect defoliation, global environmental changes, acid deposition, and rising atmospheric CO2 concentrations, have been identified as phenomena that could affect forest structure and composition. Currently, there is very little quantitative information on the resulting effect of multiple disturbances on the main parameters of forest dynamics (growth, mortality, and recruitment). Using available data from the Quebec permanent sample plots network, we analyzed the ecological response of tree species populations to the combined effect of contemporary global environmental changes, disturbance regimes, and forest management practices over the last 30 years in southern Quebec. The results indicate that the main parameters of forest dynamics changed considerably over the last three decades. The last spruce budworm outbreak initiated a successional change in coniferous stands. The basal area of Abies balsamea and Picea glauca, the most abundant coniferous species, decreased by 29.7%, while pioneer species abundance increased. For late successional deciduous species, observed changes in forest dynamics appear to be mainly associated with global environmental changes rather than with natural disturbances or forest harvesting. The results indicate that inferring responses of tree population dynamics to global environmental changes can be very complex or even misleading considering the confounding effects of other disturbance agents. The results also suggest that the ecosystem-based management approach promoted by forest ecologists, aimed at maintaining landscape stand composition and structures similar to those characterizing natural environments, will not be easily achieved. Forest ecosystems are highly dynamic and disturbances other than tree harvesting appear to have been the major factors affecting their pattern of change over the last three decades. Forest managers should consider adaptive management approaches that will consider the contemporary evolution of forest ecosystems in a changing environment.  相似文献   
14.
许多不同的技术可以促进农业生产力的持续增长,生物技术是其中最重要和最有前途的方法。因为生物技术不仅可以增加生产力。而且在环境和自然资源的保护中起重要作用,应用生物技术可以生产高产、优质、高抗性和无病植物,同时也可以提高育种效率和促进食品的工业化生产。苏云金杆菌抗虫基因是目前生物技术领域中应用最广泛的例子之一。由此而产生的抗虫植物正在广泛应用于世界各地的商业化生产。本文综述了苏云金杆菌抗虫基因的研究进展和它在未来林木遗传工程中的应用。表4参68。  相似文献   
15.
SmartStax® insect-protected corn (Zea mays L.) contains genes for six Bacillus thuringiensis (Bt) proteins controlling both lepidopteran pests and the corn rootworm complex (Diabrotica spp.). The properties of SmartStax, particularly the multiple effective modes of action (i.e., each Bt protein provides a high level of control of the target pests with a low probability of cross-resistance among the proteins), have provided the opportunity to add to previously approved structured refuge options by combining the non-Bt refuge seed with SmartStax seed in a seed mix. Seed mixes ensure that a refuge is present in every Bt field, remove concerns about grower compliance with refuge requirements, and provide grower convenience. However, seed mixes could increase the likelihood that larval insects move between Bt and non-Bt plants and vice versa. Assessing the insect resistance management (IRM) value of a seed mix refuge requires an assessment of the amount of larval movement, and the consequences of that movement, for the key target pests. The studies here present such data for control of corn rootworm by SmartStax corn, which contains the rootworm-active protein Cry3Bb1 and the binary protein Cry34Ab1/Cry35Ab1. In a growth chamber experiment, SmartStax was most effective against first instars and significantly effective against second instars, but did not control third instars. In a field study of movement from a heavily infested non-Bt plant onto surrounding plants, a larger percentage of insects successfully dispersed from the infested plant when the surrounding plants were non-Bt plants than when they were SmartStax plants. A paired-plant study showed that few larvae migrated from infested SmartStax plants and survived on nearby non-Bt plants; larvae that migrated from infested non-Bt plants had low survival if the adjacent plants were SmartStax. Replicated field studies of plant-to-plant movement indicated that the non-Bt plants in a 5% or 10% seed mix consistently supported large populations of susceptible insects and represented a productive refuge, whereas the SmartStax plants had few or no survivors. The timing of emergence from seed mix plots containing 5% or 10% non-Bt plants was more similar to that of the non-Bt plots than that of the SmartStax plots. Thus, the available growth chamber and field data indicate that a seed mix of 5% or more will provide an effective refuge for corn rootworm in SmartStax corn.  相似文献   
16.
Urban green areas can play a crucial role in establishing spaces that are valuable for pollinators. However, to help ‘pollinator-friendly’ management of urban areas, complete information on the quantity and quality of available floral reward is needed. In this paper, the nectar and pollen of six Cotoneaster species (Rosaceae) were investigated in a two-year experiment established in Lublin city, SE Poland. In temperate climate, Cotoneaster species can ensure nectar and pollen in the full spring period (May/early June) or in early summer (June). A single species can support pollinators on average for 22.9 days. Flowers of Cotoneaster species produce high quantities of nectar (2.27–9.48 mg per flower) and low amounts of pollen (0.11–0.33 mg per flower). On average, the total sugar yield in Cotoneaster species was 11.5 g/m2 (2.3–22.2 g/m2), whereas the total pollen yield was 1.3 g/m2 (0.8–2.8 g/m2). Due to the high potential for total sugar yield, C. macrophyllus, C. lucidus, and C. horizontalis should be recommended to optimize the management of food resources in urban areas. Honeybee was the main insect visitor (70.1 % of the total number of visitors); therefore, Cotoneaster species can be considered valuable for urban beekeepers. However, conservation schemes for bumblebees (21.3 % of the total number of visitors) might also benefit from arrangements with these shrubs. Nevertheless, considering Cotoneaster species in conservation protocols, good-yielding pollen plants should be introduced to compensate for insufficient nutrient intake from pollen in spring.  相似文献   
17.
锈色粒肩天牛与寄主树种关系的初步研究   总被引:9,自引:0,他引:9  
刘桂华  唐燕平 《林业科学》2002,38(3):106-113
在连续 3a的定位观测和分析基础上 ,本文初步报道了锈色粒肩天牛与文献报道中的几种寄主树种之间的关系。结果如下 :(1)根据室内饲养下成虫对不同树种的取食及产卵情况和在不同树种上接种 (卵 )的幼虫情况 ,可将几种寄主树种分为 4类 :高感树种 (国槐 )、低感树种 (云实、黄檀 )、抗虫树种 (刺槐 )、免疫树种 (旱柳 ) ;(2 )酚酸类物质在旱柳中的含量 (3 0 3~ 9 73mg·(10 0g) - 1 ) ,显著高于其它树种中的含量 (1 71~5 39mg·(10 0g) - 1 ) ,可能是锈色粒肩天牛在旱柳上表现拒食、拒产卵、拒钻蛀的重要原因。氨基酸含量较高、组分相对最全 (17种 ) ,以及较高的C N值 ,是国槐基本营养物质的显著特征 ,这可能是锈色粒肩天牛嗜食国槐 ,对其造成严重危害的根本原因。锈色粒肩天牛很少取食危害刺槐 ,这与刺槐树种的各部分C N值过低 ,造成营养失调有关。黄檀木材纤维平均长度为 0 837mm ,平均宽度为 18 90 μm ,长宽比为 5 0 96 ,其韧性是参试树种中最大的 ,因而可能造成幼虫啃食困难 ,加上木材中的C N低 (0 36 ) ,因此 ,具有较强的抗虫性。云实树皮薄而光滑 ,造成成虫产卵困难 ,因此 ,在自然状态下 ,锈色粒肩天牛不易对其产生危害。  相似文献   
18.
The influence of above-ground insect herbivory and other agents of damage to seedlings was studied in a field experiment. Nine different tree species were planted in each of five randomised blocks. The species were: Alnus glutinosa (L.) Gaertner, Betula pendula Roth., Fagus sylvatica L., Fraxinus excelsior L., Larix eurolepis Henry, Picea abies (L.) Karst., Prunus avium L., Quercus robur L. and Tilia cordata Mill. The seedlings were monitored through the 2000–2002 growing seasons. Pine weevils (Hylobius abietis L.) fed significantly more on Norway spruce seedlings than on all other tree species. The following rough preference order was obtained: Norway sprucelarch>birch, beech, oak>cherry>alder, ash, lime. Thus, during the conversion of single-species coniferous plantations to mixed-species broadleaved stands, the use of costly insecticides against pine weevil is not required. Short-snouted weevils (e.g. Strophosoma melanogrammum Forst. and Otiorhynchus scaber L.) and other insects caused leaf and needle area loss primarily during the first growing season.  相似文献   
19.
Agricultural productivity may be raised in a sustainable way by many different technologies such as biological fertilizers, soil and water conservation, biodiversity conservation, improved pest control, and changes in land ownership and distribution. Of these measures, biotechnology applications probably hold the most promise in augmenting conventional agricultural productivity, because biotechnology applications give not only the need to increase production, but also protect the environment and conserving natural resources for future generations. Biotechnology applications will have the possibilities to increase productivity and food availability through better agronomic performance of new varieties, including resistance to pests; rapid multiplication of disease-free plants; ability to obtain natural plant products using tissue culture; diagnosis of diseases of plants and livestock; manipulation of reproduction methods increasing the efficiency of breeding; and the provision of incentives for greater participation by the private sector through investments. Insect resistance through the transfer of a gene for resistance fromBacillus thuringiensis (Bt) is one of the most advanced biotechnology applications already being commercialized in many parts of the world. This paper reviews the development and the status ofBt technology and application ofBt transgenic plants in current agriculture, and discusses specific issues related to the transfer of the technology to the future of genetic engineered trees with emphasis on conifers. Biography: Tang Wei (1964-), male, Ph. Doctor, Research associate, Department of Biology, Howell Science Complex, East Carelina University, Greenville, NC 27858-4353, USA. Responsible editor: Chal Ruihai  相似文献   
20.
美观新颖的昆虫标本制作   总被引:1,自引:0,他引:1  
为了保护环境,减少昆虫资源的浪费,介绍表面皿标本,琥珀标本,蝴蝶珍藏卡等标本制作方法。  相似文献   
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