首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 625 毫秒
1.
《干旱区科学》2010,(4):294-294
<正>A book, Environments of Gurbantünggüt Desert, written by Professor Qian Yibing et al., from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, and Wu Zhaoning from Xinjiang University, has been  相似文献   

2.
Calliteara pudibunda is a univoltine, polyphagous and native species producing periodic outbreaks which have been recorded only in Europe so far. Its larvae feed on the foliage of beech, oak and several other deciduous and coniferous trees. It is very widespread in Eurasia. In Europe, it is found between the 34th and 60th parallels. In Türkiye, it occurs mainly in coastal regions. Its outbreak range had been thought to be confined between the 48th and 57th parallels in Europe until the last two decades when outbreaks occurred in Italy and Türkiye. Therefore, the southern limit of its outbreak range can be updated as the 36th parallel. The outbreaks recur every 20–30 years, typically continue for 1–2 years, and end suddenly. Favourable meteorological conditions and a temporary rarity of parasitoids seem to be the main causes of the outbreaks. The damage on hosts is not evident until the third larval instar. The affected hosts may grow new shoots the next spring, as the larvae usually do not attack the terminal shoots. Increment loss is possible, but it may not be economically significant per se. However, tree mortality can occur with the combined effects of other stress factors. The impact of parasitoids and predators during the outbreaks is low. There are also fungal species identified from larvae and pupae, some of which might have significant potential in pest management. Additionally, Bacillus thuringiensis var. kurstaki (Btk), polyhedrosis viruses and light traps can potentially be used, although management practices are not recommended in C. pudibunda outbreaks.  相似文献   

3.
Cucurbit downy mildew, caused by the oomycete Pseudoperonospora cubensis, is a devastating, worldwide-distributed disease of cucurbit crops in the open field and under cover. This review provides recent data on the taxonomy, biology, ecology, host range, geographic distribution and epidemiology of P. cubensis. Special attention is given to host-pathogen interactions between P. cubensis and its economically-important cucurbit hosts (Cucumis sativus, C. melo, Cucurbita pepo, C. maxima, and Citrullus lanatus); pathogenic variability in P. cubensis at the species, genus, and population levels; and, differentiation of pathotypes and races. Genetics and variability of host resistance and cellular and molecular aspects of such resistance are considered. A focus is given to methods of crop protection, including prevention and agrotechnical aspects, breeding for resistance—classical and transgenic approaches, chemical control and fungicide resistance. Novel technologies in biological and integrated control are also discussed. This review also summarizes the most important topics for future research and international collaboration.  相似文献   

4.
5.
Plant extracts (botanicals) are of special significance for plant protection, especially in organic farming. This is due to their origin, specific modes of action, toxicological and ecotoxicological properties as well as to ever changing legal, patent, economic and social/political issues. This paper surveys this complex background and presents data on two selected botanicals which pertain to the use of extract fractions from Glycyrrhiza glabra (sweet wood) for control of Bremia lactucae (downy mildew) in lettuce and azadirachtin for control of leafhoppers in Melissa officinalis L. Both compounds exhibited good effects in the greenhouse which were less pronounced or absent in the field. The effects of sweet wood were strongest when applied twice preventively at 5?% concentration. In the greenhouse, this resulted in a lower number of infected plants and smaller leaf areas attacked by the downy mildew pathogen at high disease pressure. Azadirachtin (plant protection chemical NeemAzal®-T/S in combination with the additive Trifolio S-forte; 1.5 l/ha + 3 l/ha in 600 l water per hektar, 3 applications, interval 7 days) was better in controlling leaf hoppers than natural pyrethrins in combination with rapeseed oil (Spruzit Schädlingsfrei; 6 l/ha in 1,000 l water per hektar, 1 application) in the greenhouse and exhibited very high insecticidal efficacy almost equivalent to that of thiacloprid (Calypso 480 SC; 0.12 l/ha in 400 l water per hektar, 1 application) at moderate disease pressure. Thiacloprid, however, is not applicable in organic farming. In order to introduce these promising results in practical plant protection further fundamental studies are needed. These can only be realized by a joint effort of private companies, research and plant protection institutions, as well as public funding bodies. This article is not meant as a presentation of “perfect” results, it is rather an example of the problems and pitfalls that need to be overcome during development of a botanical and its applications. They are the reason why the market for botanicals will remain small.  相似文献   

6.
Abstract

Panolis flammea that had survived an aerial spraying programme of fenitrothion were compared in a series of laboratory experiments with moths that had not been within the sprayed area, to assess the effects of sub‐lethal spray application on various life history parameters. Emergence success was not significantly different between the two treatments and the sex ratio in both cases approximated 1:1. The bionomics of moths surviving in the sprayed plots were different in several respects from those taken from unsprayed plots. The former emerged from pupae later, had lower levels of fecundity and a longer pre‐oviposition period. Females from sprayed plots were also heavierthan males and their weight was positively correlated with fecundity, whereas neither of those traits were shown by unsprayed moths. A number of other bionomic traits were not significantly different in sprayed or unsprayed groups. Analysis of the population growth rates of P. flammea from areas of the forest where control was either ineffective or effective, revealed no significant differences. The implications of these results for the population dynamics of P. flammea are discussed.  相似文献   

7.
Quorum sensing controls a number of key processes in growth, reproduction and virulence of many gram-negative bacteria via signalling molecules or autoinducers. It can control, for instance, the production of pectic enzymes which are virulence factors in disease. Pseudomonas fluorescens 5064 produces biosurfactants which are important for bacterial establishment on the plant surface prior to causing disease in broccoli. The aim of this paper was to determine if biosurfactant production in this bacterium is controlled via quorum sensing. To do this, 35 surfactant-minus Tn5 mutants of P. fluorescens 5064 were screened for their abilities to produce a quorum sensing signal. Six of these biosurfactant-deficient mutants showed a large reduction in quorum sensing signal production and varied in their abilities to cause disease. In one mutant, 6423, which contains a single Tn5 insertion, the production of the signal was almost eliminated. Synthetic quorum sensing signal and quorum sensing signal extracted from wild type P. fluorescens 5064 restored biosurfactant production by addition to the culture in mutant 6423. The quorum sensing signal in wild type P. fluorescens 5064 was identified by high pressure liquid chromatography and mass spectrometry as N -3-hydroxyoctanoyl-homoserine lactone.  相似文献   

8.
Journal of Plant Diseases and Protection -  相似文献   

9.
10.
Genetically modified trees (GM trees) are long-living plants. In regard to their special ecological and economic importance deployment of genetically modified trees is controversial because of the possible risks they are involved.Commercial use of GM trees for example as a plantation culture is supported by proponents, if they were previously subjected to a comprehensive risk analysis and safety assessment. In contrast, many critics exclude a commercial use of GM trees completely. They demand to stop the research.In this paper, the possibilities of a sustainable, environmentally sound and resource-efficient use of GM trees are discussed. Arguments are given in favor of GM trees in respect to both, as a source of renewable raw material to cover an increasing demand for energy and chemical raw materials.Besides, arguments are given in favor of GM trees to mitigate effects of climate change in comparison to agronomical energy crops such as maize, sugar beet and cereals.Finally, an overview of an international project on risk assessment of GM trees (recently approved by the European Union) is given. The paper concludes with a presentation of requested and approved field trials of GM trees in the last five years in Europe.  相似文献   

11.
The biology and predatory efficiency of Geocoris ochropterus Fieber (Hemiptera: Geocoridae) has been studied extensively against many insect pests, but information on functional response of different stages of G. ochropterus to Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is lacking so far. The functional response of different stages of G. ochropterus to varying densities of eggs of H. armigera was investigated in the laboratory at 26?±?2°C, 65?±?2% RH and 12 L: 12D. Immature stages i.e. 3rd, 4th, 5th instar and adult predator exhibited type II functional response. Handling time decreased with increasing predator’s developmental stage. Adult G. ochropterus followed by fifth instar exhibited highest egg consumption and attack rate compared to other stages. Functional response parameters indicate that the adult and fifth instar of G. ochropterus were more voracious and efficient than other juveniles and might be useful as promising biocontrol agent against H. armigera.  相似文献   

12.
Limiting factors in organic potato production are predominantly nitrogen and infestation with late blight disease (Phytophthora infestans). To maintain high yields, organic nitrogen fertilization, presprouting and control of potato late blight with copper-treatments are potential measures. Field trials were conducted from 2005 to 2007 to evaluate which single measure and combination of measures were most likely to achieve the best results. Organic nitrogen fertilization led to an average yield increase during all three years of trial. Tuber presprouting accelerated plant emergence and also increased yields. It was the most effective single measure, provided that late blight disease appeared (2005 and 2007). In absence of infection with late blight, presprouting had no influence on potato yield (2006). Copper-treatments only had a positive impact on potato yield in combination with optimized plant nutrition and presprouting. Varieties with early tuber development (e.?g. “Princess”) have almost completed formation of yield when infection with late blight sets in. Up to this time, all measures to increase yield should be finished.  相似文献   

13.
14.
A plant-growth-promoting fungus (PGPF), Talaromyces sp. was isolated from an agricultural field in southwestern Japan. We found that this fungus emitted several terpenoid-like volatiles including β-caryophyllene. Then we investigated the effect of β-caryophyllene on promoting the growth and inducing resistance of Brassica campestris L. var. perviridis. The compound significantly enhanced the growth of seedlings and their resistance to Colletotrichum higginsianum. On the basis of these results, we discuss the role of β-caryophyllene in the activities of PGPF.  相似文献   

15.
Modern methods in plant production and crop protection are closely related to modern technologies. Near-range and remote sensing, like hyper- and multispectral sensors or thermography, in precision pest management possess multiple opportunities to increase the productivity of agricultural production systems and do them more environmentally acceptable. Experiments are carried out on sugar beet plants and their pathogens to investigate the use of imaging and non-imaging hyperspectral sensors referring to the following questions: Is early detection of infection by pathogens possible? What is the potential to differentiate damage causing organisms?  相似文献   

16.
Aggregations of palm aphid Cerataphis brasiliensis (Hempel) (Aphididae: Hemiptera) on the unfurled spindle leaf of ‘Kalparaksha’ variety of coconut, a selection from Malayan Green Dwarf, is reported for the first time. C. brasiliensis has not yet been observed from other coconut varieties, viz., West Coast Tall, Chowghat Orange Dwarf, Chowghat Green Dwarf, and Dwarf x Tall hybrids planted in the research farm of Central Plantation Crops Research Institute, Kayangulam, Kerala, India. Only the apterous form of the palm aphid was noticed in the semi-tall variety and a variety-induced emergence of C. brasiliensis is indicated under natural conditions. Due to the presence of two phoretic ant species, no natural predator was observed in the aphid colonies. Two sprays of dimethoate (0.05%) at an interval of 15–20 days were effective in suppression of the pest on Kalparaksha.  相似文献   

17.
The use of a selective insecticide is highly recommended for Integrated Pest Management programs. Plenum (a.i.: pymetrozine; Syngenta Agro), a systemic insecticide, is regarded as a good candidate for use in situations where plant-sucking insects have to be controlled and where natural enemies can play a substantial role as biological control agents. In this context, the effects of Plenum on a host–endoparasitoid relationship were investigated. Potato aphids Macrosiphum euphorbiae were reared for 4 days on an artificial diet supplemented with a low concentration of Plenum (sublethal concentration inducing 15% aphid mortality) before parasitization by the endoparasitoid Aphidius ervi. The development of A. ervi larvae was negatively affected, especially during the early stages of development, and the sex ratio of the progeny was strongly male-biased. Moreover, the host-choice experiment showed that A. ervi was not able to discriminate between control and Plenum-contaminated aphids. These results show that Plenum may not be as selective as it was previously thought to be, and the observed effects need to be considered when developing IPM systems.  相似文献   

18.
In the year 2002, in Beytepe, near Ankara, the food spectrum of Great Tit (Parus major), House Sparrow (Passer domesticus) and Starling (Sturnus vulgaris) was determined, using the neck-ringing method. The food analysis of the bird species mentioned above proved their importance in biological control methods for destruction of organisms harmful for the forest. The proportion of injurious insects in the food spectrum of the bird species investigated is as follows: Starling 60,6 % (n = 20), House Sparrow 56,4 (n = 22) and Great Tit 78,8 % (n = 41).
Die Schädlingsvertilgung einiger Singvogelarten in einem Schwarzkiefern-Zedern-Wald in Beytepe bei Ankara, Türkei
  相似文献   

19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号