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201.
W. Oßwald F. Fleischmann D. Rigling A. C. Coelho A. Cravador J. Diez R. J. Dalio M. Horta Jung H. Pfanz C. Robin G. Sipos A. Solla T. Cech A. Chambery S. Diamandis E. Hansen T. Jung L. B. Orlikowski J. Parke S. Prospero S. Werres 《Forest Pathology》2014,44(3):169-190
This review comprises both well‐known and recently described Phytophthora species and concentrates on Phytophthora–woody plant interactions. First, comprehensive data on infection strategies are presented which were the basis for three models that explain invasion and spread of Phytophthora pathogens in different woody host plants. The first model describes infection of roots, the second concentrates on invasion of the trunk, and the last one summarizes infection and invasion of host plants via leaves. On the basis of morphological, physiological, biochemical and molecular data, scenarios are suggested which explain the sequences of reactions that occur in susceptible and tolerant plants following infections of roots or of stem bark. Particular emphasis is paid to the significance of Phytophthora elicitins for such host–pathogen interactions. The overall goal is to shed light on the sequences of pathogenesis to better understand how Phytophthora pathogens harm their host plants. 相似文献
202.
High season for the Norwegian Brown crab fishery (Cancer pagurus L.) is from August to October when meat yield (MY) is high, especially for female crabs. However, the quality of hard‐shelled crabs may vary between and within regions also, at this time of the year. A pilot study was conducted to examine whether feeding could increase MY in wild‐caught medium‐quality females caught during four periods from July to November. Feed intake was compared for crabs fed at different temperatures (3, 5, 8, 10 and 12°C). The crabs were fed three times a week in periods from 15 to 20 days. Feed intake increased with temperatures. Quality, as assessed by MY, was higher for all fed groups compared with reference groups. A clear pattern in quality improvement was seen according to season. Hepatosomatic index increased more than the gonadosomatic in July, slightly more in August, while gonadosomatic development was higher in September. In October, some spawning occurred. The result indicates that feeding had a positive effect, which seemed to increase with increasing temperature. We suggest that the temperature should be at least 12°C in order to achieve an optimal gain in MY when the feeding period is 3 weeks. 相似文献
203.
To learn the evolutionary trajectories of caste differentiation in eusocial species is a major goal of sociobiology. We present an explanatory framework for caste evolution in the eusocial wasp genus Polistes (Vespidae), which is a model system for insect eusocial evolution. We hypothesize that Polistes worker and gyne castes stem from two developmental pathways that characterized the bivoltine life cycle of a solitary ancestor. Through individual-based simulations, we show that our mechanistic framework can reproduce colony-level characteristics of Polistes and, thereby, that social castes can emerge from solitary regulatory pathways. Our explanatory framework illustrates, by specific example, a changed perspective for understanding insect social evolution. 相似文献
204.
We critically discuss the impact of sustainable development initiatives in Kerala, India, on biodiversity and on women farmers in the matrilineal Adivasi community of the Kurichya-tribe in Wayanad. By contextualizing development programs regarding the specifically gendered access to land, division of labor, distribution of knowledge and decision-making power, we situate our analysis within the theoretical framework of feminist political ecology. We first outline women’s gaining of social and political space in local self-government institutions (Panchayath) and then critically discuss the impacts of women’s farming groups (Joint Liability Groups: JLGs). Decentralization and development programs have aimed at empowering women and reducing poverty through improved food security. However, little success has materialized, as patriarchal power structures concerning decision-making processes as well as control over the most valuable resources (land and rice) and traditional knowledge have been maintained. Whereas women’s self-help groups (Kudumbasree) in Kerala have enhanced their position, women’s farming groups (JLGs), by contrast, have brought little betterment. In some cases they have even downsized women’s management and knowledge of resources related to agriculture and do not integrate or enhance Kurichya women’s knowledge. As some women are now introducing high-yielding rice seeds and fertilizer and as it is impossible for them to control land and get access to traditional rice seeds—the domain of men—we contest the notion of women being considered the preservers of agrobiodiversity. We argue, rather, that the construction and transformation of ecological traditional knowledge is highly dependent on the gendered multi-scaled power structures of state and community. 相似文献