Potato insect pest management

正Having an estimated production of 388 million tons in 2017(FAO2019),potatoisoneoftheworld’smostimportant foodcrops,alongwithrice,wheat,andmaize.Potato plantscanadapttodifferentagriculturalenvironments and are widely grown over many latitudes and elevations(Douchesetal.2004).Inadditiontoitsconsumptionin Europe, North America and countries of the former Soviet Union, potato is now also popularized in Africa and Asia,     

昆虫免疫进化的研究进展

昆虫在长期的进化过程中发展出了一套独特的免疫系统,由细胞免疫和体液免疫组成。随着分子生物学研究技术的发展,人们发现昆虫具有复杂的免疫系统,在病原体识别、信号转导途径及效应机制等方面与哺乳动物均高度相似,这些防御机制有着共同的进化起源。越来越多的研究表明昆虫的免疫具有特异性,不仅有免疫记忆,还能改变自身的免疫细胞去对付不同类型的微生物。     

“平阳特早”茶园3种主要害虫与其天敌 在数量、时间和空间上的关系

为了利用天敌进行茶园害虫的综合防治,分析了"平阳特早"茶园不同时段害虫与其天敌之间在种群数量、时间和空间上的关系。采用灰色系统分析法和生态位分析法,对2010年及2011年春夏季茶园假眼小绿叶蝉、广翅蜡蝉和卵形短须螨与其捕食性天敌在数量、时间和空间格局等关系方面进行分析,对每一种天敌对应的关联度、生态位重叠指数和相似性比例等参数标准化后相加,按照参数标准化值之和大小排序得出:2010年春夏季,对假眼小绿叶蝉控制潜力最高的3种天敌是斜纹猫蛛,龟纹瓢虫和草间小黑蛛;对八点广翅蜡蝉控制潜力最高的3种天敌是草间小黑蛛、粽管巢蛛和八点球腹蛛;对卵形短须螨控制潜力最高的3种天敌是粽管巢蛛、草间小黑蛛和龟纹瓢虫。2010年秋冬季,对假眼小绿叶蝉控制潜力最高的3种天敌是三突花蟹蛛、草间小黑蛛和斜纹猫蛛;对八点广翅蜡蝉控制潜力最高的3种天敌是粽管巢蛛、斜纹猫蛛和鳞纹肖蛸;对卵形短须螨控制潜力最高的3种天敌是粽管巢蛛、斜纹猫蛛和异色瓢虫。2011年春夏季,对假眼小绿叶蝉控制潜力最高的3种天敌是八点球腹蛛、异色瓢虫和三突花蟹蛛;对八点广翅蜡蝉控制潜力最高的3种天敌是草间小黑蛛、异色瓢虫和龟纹瓢虫;对卵形短须螨控制潜力最高的3种天敌是龟纹瓢虫、草间小黑蛛和八点球腹蛛。3个调查时间段之间,3种害虫的优势种天敌有较大差别。     

Computer networks as social networks

Computer networks are inherently social networks, linking people, organizations, and knowledge. They are social institutions that should not be studied in isolation but as integrated into everyday lives. The proliferation of computer networks has facilitated a deemphasis on group solidarities at work and in the community and afforded a turn to networked societies that are loosely bounded and sparsely knit. The Internet increases people's social capital, increasing contact with friends and relatives who live nearby and far away. New tools must be developed to help people navigate and find knowledge in complex, fragmented, networked societies.     

Histone acetylation in insect chromosomes

Acetylation of histones takes place along the salivary gland chromosomes of Chironomus thummi when RNA synthesis is active. It can be observed but not measured quantitatively by autoradiography of chromosome squashes. The "fixatives" commonly used in preparing squashes of insect chromosomes preferentially extract the highly acetylated "arginine-rich" histone fractions; the use of such fixatives may explain the reported absence of histone acetylation in Drosophila melanogaster.     

Mosquitoes feeding on insect larvae

Caged Aedes aegypti and Culex tarsalis are attracted to insect larvae, engorge on their body fluids, and produce viable eggs. Attractiveness of the larvae is related to their size, shape, and color but not to their movement. The possibility that wild mosquitoes substitute insect hemolymph for vertebrate blood is discussed.     

昆虫组织培养研究进展

昆虫组织培养目前已在生物学领域成为重要的研究工具.特别是成功的筛选出对杆状病毒敏感的细胞系及空斑技术的应用,使病毒的基础研究达到分子水平,如病毒的遗传改良、DNA的复制、蛋白质的合成及病毒的物理图谱等.近年来,人们已成功地利用昆虫组织培养进行病毒杀虫剂的大量生产,用于害虫生物防治,更显示出昆虫组织培养的重要意义.为此,本文对昆虫组织培养的研究进展作简单阐述.     

Circadian clock in insect photoperiodism

Night-interrluption experiments with the wasp Nasonia vitripennis maintained in 48- and 72-hour light: dark cycles reveal two and three peaks of light sensitivity (diapause inhibition), respectively. The first peak is 19 hours after lights-on in all regimes tested; the later peaks occlur at 24-hour intervals thereafter, providing evidence for the circadian nature of the photoperiodic clock in this insect.     

Ecology of insect host-parasitoid communities

Although conclusive evidence is lacking for its establishment, the thesis that complexity adds stability to communities is probably accepted by the majority of ecologists. I believe this attitude found its origins in the indisputable fact that there are latitudinal and altitudinal changes in community complexity. As one progresses northward or southward from the equator, or higher in altitude in most parts of the world, one cannot help but notice that communities tend to become simpler, that is, there are fewer species per community. At the same time, these communities appear to become less stable. But perhaps this change in stability is in appearance only; they appear to be less stable because of the relatively greater number of individuals comprising each species population in temperate areas. Each population, because of its greater numbers, is therefore conspicuous, and changes in these numbers are noticed. We are particularly aware of such changes because populations in these areas of the world have been comparatively well studied. Many of the most studied populations include species of economic importance where changes in population numbers are vital to agricultural or forestry practices. Equatorial populations, on the other hand, contain smaller numbers of individuals of each species because of the greater number of species present. Number changes are simply not as noticeable because the population itself is not as obvious among the other populations. It may be that when (if ever) we have as much data on equatorial populations as we have on those of temperate climates, we will find fluctuations of equal relative magnitude (but not of equal numbers, of course). If, on the other hand, we really do find a correlation between complexity and stability, the suggestion by May (12) that stability permits complexity may be well worth investigating. Because of its organization and physical setting, the Rhopalomyia community I have studied might be expected to have considerable stability. In fact, however, it does not. Each of the populations in the community fluctuates greatly and irregularly in both percentages and numbers, and these populations apparently become locally extinct occasionally, because they sometimes cannot be found even in extensive collections. After studying several of the more important parasitoid species, it is evident to me that there is little or nothing about their interactions that might induce greater community stability. Each species seems to have evolved into the community with no higher purpose than simply to usurp what it can from some other member, and it does this by concentrating its energies on better competitive mechanisms rather than higher reproductive capacities. There are never empty niches to be filled by organisms having the "correct specifications" because new niches are created out of parts of older, broader niches which were occupied by other, more r-selected organisms. Thus, perhaps we have read too much into community organization. Perhaps the "ifiling of niches" is essentially nothing more than the haphazard result of competitive jostling among species; and that as communities develop, they are not necessarily programmed for such things as greater stability or better energy utilizationthe species merely become more closely packed.     

The sociogenesis of insect colonies

Studies on the social insects (ants, bees, wasps, and termites) have focused increasingly on sociogenesis, the process by which colony members undergo changes in caste, behavior, and physical location incident to colonial development. Caste is determined in individuals largely by environmental cues that trigger a sequence of progressive physiological restrictions. Individual determination, which is socially mediated, yields an age-size frequency distribution of the worker population that enhances survival and reproduction of the colony as a whole, typically at the expense of individuals. This "adaptive demography" varies in a predictable manner according to the species and size of the colony. The demography is richly augmented by behavioral pacemaking on the part of certain castes and programmed changes in the physical position of colony members according to age and size. Much of what has been observed in these three colony-level traits (adaptive demography, pacemaking, and positional effects) can be interpreted as the product of ritualization of dominance and other forms of selfish behavior that is still found in the more primitive insect societies. Some of the processes can also be usefully compared with morphogenesis at the levels of cells and tissues.     

Social networks and information access: Implications for agricultural extension in a rice farming community in northern Vietnam

Village communities are not homogeneous entities but a combination of complex networks of social relationships. Many factors such as ethnicity, gender, socio-economic status, and power relations determine one’s access to information and resources. Development workers’ inadequate understanding of local social networks, norms, and power relations may further the interests of better-off farmers and marginalize the poor. This paper explores how social networks function as assets for individuals and households in the rural areas of developing countries and influence access to information and benefits from research and development. A case study of such networks in Phieng Lieng village, in the northern mountains of Vietnam, provides evidence for the need for the efficient delivery of extension services and research and development interventions at the micro level. Lan Anh Hoang is a social scientist with a special interest in social networks and gender and power relations in rural areas. She is currently working on her PhD at the School of Development Studies, University of East Anglia (UK) on “Gender relations, household power hierarchies, and social norms in migration decision-making in rural Vietnam.” She was involved in the Mountain Agrarian Systems Program in Bac Kan Province from 1999 to 2002. Jean -Christophe Castella is a production systems agronomist from the Institut de Recherche pour le Développement (IRD, France). Between 1998 and 2003, he coordinated a joint research program on “comprehensive study of land use changes in northern Vietnam uplands” in partnership with the Vietnam Agricultural Science Institute (VASI, Hanoi, Vietnam) and the International Rice Research Institute (IRRI, Philippines). Paul Novosad was involved with the Mountain Agrarian Systems program from January to July 2002. He helped to synthesize the results of field research and also was involved in analyzing data related to social networks. Since fall 2002 he studies Public Administration and International Development at the Kennedy School of Government in the United States (Cambridge, Massachusetts).