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1.
In order to conduct studies concerning genetic variability of pollen beetles (Meligethes aeneus), a genotyping protocol was established. No genome information is available for pollen beetles so the amplified fragment length polymorphism (AFLP) technique was chosen since it does not depend on any prior sequence information of the samples and also is a sensitive and robust technique. However, several modifications were needed in order to adapt the method for analysis of pollen beetles. Basic modifications included (i) alterations of DNA purification, (ii) use of two six-cutter restriction enzymes, (iii) and modified PCR conditions. This protocol resulted in a favourable number of fragments of an appropriate size range for standard gel analysis by a DNA sequencer applicable to a single insect and even body parts enabling different assays to be conducted on a single specimen. Pollen beetles from different areas of Sweden were analysed to verify the reproducibility and efficacy of the protocol as well as for phenetic analysis. The high reproducibility of the modified AFLP protocol allows it to be used as a reliable tool for genotype analysis of pollen beetles.  相似文献   

2.
During an early stage of migration into a field of oilseed rape in the spring of 1988, more pollen beetles were observed on the double-low variety, Ariana, than on the adjacent single-low varieties, Bienvenu and Mikado. More beetles were found on open flowers on terminal racemes than on yellow and green flower buds on lateral racemes. Five alkenyl, three indolyl and two aromatic glucosinolates were identified in the floral tissues of oilseed rape. The major compounds were progoitrin (2-OH, 3-butenyl) and glucobrassicanapin (4-pentenyl). There were no differences in the types and concentrations of glucosinolates present in the terminal and lateral racemes of any variety, and only small differences between single- and double-low varieties. Concentrations of glucosinolates in floral tissues of crops grown with a little nitrogen were twice those of well-fertilised crops. There was no association between the number and distribution of pollen beetles on plants and the amounts or types of glucosinolates present in floral tissues.  相似文献   

3.
Abstract 1 Egg loads from field collected pollen beetles (Meligethes aeneus Fab., Coleoptera: Nitidulidae) were determined by dissecting beetles caught at the beginning and end of the putative daily oviposition period. Field collected beetles were offered Brassica napus (L.) plants in cages for 8 (morning and early afternoon), 16 (overnight), and 24 h to ascertain the number of eggs laid during these time periods. 2 Most eggs were laid in the morning and early afternoon. The proportion of gravid females was higher at the beginning of the oviposition period than at the end. Most females in the morning carried two eggs, whereas one egg was more common in the afternoon. 3 We hypothesized that the number of eggs laid during the oviposition period would be equivalent to the difference between egg loads at the beginning and end of oviposition. This was not the case; differences in egg loads were significantly lower than number of eggs laid. However, the number of eggs laid was equivalent to the egg load at the beginning of the oviposition period, suggesting that eggs available in the morning are laid during the following day. 4 Population estimates of daily oviposition rates, approximately 0.7 eggs per beetle and day, were close to estimates from laboratory studies when the proportion of gravid females was taken into consideration.  相似文献   

4.
黄家俊  张强  张生  陈晓宏 《生态学报》2017,37(13):4444-4455
基于信息熵理论对新疆降水序列的时空变异性进行研究。利用边际熵研究不同时间尺度降水序列的变化特征。利用分配熵和强度熵分别研究降水量和降水天数年内和年代际(10a)分配情况。利用改进的Mann-Kendall趋势检验法分析新疆降水过程不确定性变化趋势。研究表明:(1)新疆降水量与降水天数年内分配不均匀性主要表现为由南向北减小的空间分布特征;(2)新疆不同尺度的降水序列不确定性具有明显空间特征;(3)越降水越稀少的地区,降水量与降水天数变异性就越大。本研究对该区域降水时空变异研究与水资源规划具有重要意义。  相似文献   

5.
盐碱地是潜在的可利用耕地资源,但土壤盐碱化严重制约了农业生产的可持续发展。基于棉花机械化程度低、劳动力成本和生产资料投入剧增、比较效益下降和实施粮食生产安全战略等因素影响,我国长江流域和黄河流域棉花面积锐减,种植区域向内陆盐碱旱地或滨海盐碱地转移,但目前针对盐碱地转Bt基因棉种植可能带来的生态安全性问题研究甚少,正成为国内外研究的焦点和热点。伴随着棉花向盐碱地大面积转移种植趋势,检测盐胁迫是否影响转基因抗虫棉抗虫性,明确其影响程度,直接关系到转基因抗虫棉种植的安全性,也是目前抗虫棉扩大生产中迫切需要解决的问题。以非转基因棉花为对照,分别在低盐、中盐和高盐土壤种植的棉花的苗期、蕾期和花铃期采样,室内测定了转Bt基因棉花叶片对棉铃虫幼虫校正死亡率和外源蛋白表达量。研究结果发现盐分胁迫下转Bt基因棉花苗期叶片对棉铃虫幼虫校正死亡率下降了9.22%—47.46%,蕾期下降了31.61%—45.42%,花铃期下降了3.59%—18.52%;土壤盐分显著降低了转Bt基因棉花叶片中外源蛋白的表达量,苗期功能叶外源蛋白表达量下降了7.66%—29.86%;蕾期下降了3.77%—36.85%;花铃期下降了18.13%—41.02%;相关性分析表明,盐分胁迫条件下转Bt基因棉花叶片中外源蛋白表达量与其对棉铃虫抗性程度存在正相关关系。结果表明,盐碱土壤显著降低了转Bt基因棉花叶片外源杀虫蛋白表达量,从而导致转Bt基因棉花叶片对棉铃虫的抗虫性下降。研究土壤盐分对转Bt基因棉花对棉铃虫的影响及其作用机制,可为建立盐碱地转Bt基因棉花田害虫综合防控技术体系、转Bt基因棉花环境安全评价及转Bt基因棉安全管理提供依据。  相似文献   

6.
J. C. Daly 《Genetica》1993,90(2-3):217-226
Pyrethroid resistance inHelicoverpa armigera provides a model system in which to study evolution in natural populations. Resistance is seen to evolve as a consequence of selection pressure that varies within and between life-stages and gene flow. Although three different mechanisms are involved, present day fluctuations in phenotype frequency can be explained by variation in only one of these, metabolic resistance, that is inherited as a single, incompletely dominant gene,mfo. Selective mortality of phenotypes occurs in both larvae and adults in the presence of the pyrethroid insecticides. Although most individuals of all three genotypes are killed in young larvae, selection in this age-class contributes significantly to evolution of resistance. While there is some evidence of reduced fitness of resistant pupae during winter diapause, most of the decline in resistance frequencies each spring occurs as a result of immigration of susceptible individuals into insecticide-treated populations.  相似文献   

7.
Plant quality is one of the main factors influencing the fitness of phytophagous insects. Plant quality can vary not only among genotypes of the same host plant species, but also relative to the insect sex or its life stage. In the present study, the performance of larvae and adults of the pollen beetle (Meligethes aeneus F., Coleoptera: Nitidulidae), a major insect pest of oilseed rape crops, is compared on six genotypes of oilseed rape (Brassica napus). All of the traits that are measured vary among genotypes, and comprise larval developmental duration, life span of unfed emerging adults and survival time of field‐sampled adults fed with pollen from the different genotypes. No correlation is found between insect performance and quantity of food available, showing that the quality of the food (i.e. pollen) is the fitness determinant for this insect species. Additionally, the performance of larvae and adults is also not correlated despite use of the same plant genotypes, suggesting that the determinants of pollen quality differ at least partially between both life stages. It is hypothesized that this may be a result of extensive differences in diet breadth between the life stages: larvae are specialists of brassicaceous plants, whereas adults are generalists. Finally, it is suggested that the manipulation of plant quality to increase pollen beetle development time may comprise a valuable strategy for favouring biological control by natural enemies of this pest; for example, as a result of extending the vulnerability window of larvae to attack by parasitoids.  相似文献   

8.
广东省不同区域农田土壤酸化时空变化及其影响因素   总被引:1,自引:0,他引:1  
基于广东省1980s、2010年以及2015年3期土壤数据,对全省不同区域农田耕作层土壤pH值的时空变异特征进行分析,并初步探讨了可能导致土壤pH变化的因素.结果表明: 不同时期广东全省土壤pH值空间分布格局变化显著. 全省农田土壤在1980s—2010年间,pH整体下降了0.3,呈酸化趋势,2010—2015年,土壤pH上升了0.09,但不均匀势态有所增强,酸碱分化趋势较明显. 从各区域看,1980s—2010年,各区域土壤均呈现酸化趋势;2010—2015年,珠三角地区农田土壤pH均值上升了0.27,而东、西两翼土壤pH均值分别下降了0.05、0.15,山区土壤pH变化不明显. 分析表明:广东省各地区土壤酸化除受土壤自身及降水等自然因素影响外,酸雨、不合理施肥以及高产作物高复种的种植结构等人为因素也是导致土壤酸化的主要原因;工业化、城市化、矿山开发和测土配方施肥的推广导致局部地区土壤pH值有所上升. 研究结果可为不同区域控制缓解土壤酸化、提高耕地质量提供理论指导.  相似文献   

9.
The extent of genetic variation and levels of temporal and spatial heterogeneity was investigated, at six polymorphic protein‐coding loci, in wild Atlantic salmon Salmo salar populations from six rivers of Asturias (Northern Spain). Also, stocks from northern Europe that were among those introduced to repopulate Asturian Rivers, and other wild Spanish and European populations were characterized. The lack of temporal variation observed suggests that effective population sizes of Asturian populations are sufficiently large to prevent extreme levels of genetic drift and that the introduced fish had a negligible contribution to the fisheries of Asturian rivers.  相似文献   

10.
Nearly 30% of emerging infectious disease events are caused by vector‐borne pathogens with wildlife origins. Their transmission involves a complex interplay among pathogens, arthropod vectors, the environment and host species, and they pose a risk for public health, livestock and wildlife species. Examining habitat associations of vector species known to transmit infectious diseases, and quantifying spatio‐temporal dynamics of mosquito vector communities is one aspect of the holistic One Health approach that is necessary to develop effective control measures. A survey was conducted from May to August, 2010 of the abundance and diversity of mosquito species occurring in the mixed‐grass prairie habitat of the Smoky Hills of Kansas. This region is an important breeding ground for North America's grassland nesting birds and, as such, it could represent an important habitat for the enzootic amplification cycle of avian malaria and infectious encephalitides, as well as spill‐over events to humans and livestock. A total of 11 species, belonging to the three genera Aedes, Anopheles, and Culex, was collected during this study. Aedes nigromaculis, Ae. sollicitans, Ae. taeniorhynchus, Culex salinarius, and Cx. tarsalis accounted for 98% of the collected species. Multiple linear regression models suggested that mosquito abundances in the grasslands of the central Great Plains were explained by meteorological and environmental variables. Temporal dynamics in mosquito abundances were well supported by models that included maximum and minimum temperature indices (adjusted R2= 0.73). Spatial dynamics of mosquito abundances were best explained by a model containing the following environmental variables (adjusted R2=0.37): ground curvature, topographic wetness index, distance to woodland, and distance to road. The mosquito species we detected are known vectors for infectious encephalitides, including West Nile virus. Understanding the microhabitat characteristics of these mosquito species in a grassland ecosystem will aid in the control and management of these disease vectors.  相似文献   

11.
Jump AS  Rico L  Coll M  Peñuelas J 《Heredity》2012,108(6):633-639
Identification and quantification of spatial genetic structure (SGS) within populations remains a central element of understanding population structure at the local scale. Understanding such structure can inform on aspects of the species' biology, such as establishment patterns and gene dispersal distance, in addition to sampling design for genetic resource management and conservation. However, recent work has identified that variation in factors such as sampling methodology, population characteristics and marker system can all lead to significant variation in SGS estimates. Consequently, the extent to which estimates of SGS can be relied on to inform on the biology of a species or differentiate between experimental treatments is open to doubt. Following on from a recent report of unusually extensive SGS when assessed using amplified fragment length polymorphisms in the tree Fagus sylvatica, we explored whether this marker system led to similarly high estimates of SGS extent in other apparently similar populations of this species. In the three populations assessed, SGS extent was even stronger than this previously reported maximum, extending up to 360 m, an increase in up to 800% in comparison with the generally accepted maximum of 30-40 m based on the literature. Within this species, wide variation in SGS estimates exists, whether quantified as SGS intensity, extent or the Sp parameter. Consequently, we argue that greater standardization should be applied in sample design and SGS estimation and highlight five steps that can be taken to maximize the comparability between SGS estimates.  相似文献   

12.
王振波  王新明 《生态学报》2019,39(4):1226-1239
农民专业合作社是推进我国乡村振兴、精准扶贫战略以及实现小农户与农业现代化发展有机衔接的重要力量。基于"过程-格局-机理"思维,对2007—2013年京津冀13个地市种植业、养殖业、供销与农机专业合作社的时空演化特征及其影响因素进行分析。结果表明:京津冀种植业、养殖业、供销与农机专业合作社数量总体上呈逐年增长趋势,合作社数量与增长速度均为种植业养殖业供销农机;种植业与养殖业专业合作社呈现"两核一带"空间格局,供销与农机专业合作社分布的梯度特征明显,合作社数量为中部南部北部,四类农民专业合作社分布均存在明显的空间负相关性;空间误差模型对种植业与供销专业合作社有更好的拟合效果,空间滞后模型对养殖业与农机专业合作社有更好的拟合效果;地理因素、经济发展水平、第一产业发展水平对四类专业合作社的发展均有显著的正向影响;市场需求对种植业、养殖业合作社影响最大,第一产业发展水平对供销、农机合作社影响最大。  相似文献   

13.
The Native Fishes Work Group, formed in 1991, developed and implemented a protocol to enhance the dwindling razorback sucker population in Lake Mohave, Arizona-Nevada. This large, genetically diverse population is severely reduced in size as a result of recruitment failure associated with predation on larvae. To circumvent this problem, wild larvae are captured, reared in protective custody until they are large enough to escape predation, and then released back into the lake. We present results of a monitoring program designed to assess the effectiveness of the sampling design in transmitting the high genetic diversity found in wild adults. Variation in a fragment from the mitochondrial DNA gene cytochrome b was examined by analysis of single-stranded polymorphisms and direct sequencing. Samples were characterized from three life history stages. Characterization of wild adults verified previous results that identified considerable diversity and provided baseline data. Samples of larvae from several temporal collections from throughout the spawning season and four geographical areas were characterized for 7 years (1997-2003) to assess the transmission of genetic variation from wild adults to larvae. Several analyses identified significant differences among temporal collections, resulting from sampling errors associated with finite number of females spawning at a given time and place. Comparisons among areas and years failed to identify significant variation, indicating that pooled collections for each year possess the same levels and patterns of genetic variation. Examination of repatriates representing 11 years (1992-2002) also failed to identify significant differences among cohorts; however, some sample sizes were small and the amova may lack sufficient power to detect differences. Contrasts of wild adults, larvae, and repatriates identified statistically significant differences among collections within these three groups; however, levels of variation are small and not biologically meaningful. More importantly, this analysis failed to detect significant differences among adults, larvae, and repatriates indicating that the program has been achieving its goal of transmitting variation from adults through the larvae and into the repatriate population. The reproductive capability of repatriates has not been examined, so it is unknown if the program will maintain genetic variation found in the original adult population. This will be most easily achieved by periodic monitoring of genetic variation in larval samples. If levels of variation become reduced in repatriates, levels and patterns of diversity in larvae are also expected to become reduced, and deviations in estimates of genetic diversity may become larger and more frequent. If this is the case, intervention may be necessary to ensure that certain individuals are not over-represented in the repatriate population.  相似文献   

14.
Trichoplusia ni is a subtropical moth that migrates annually from southern California to southern British Columbia, Canada where it invades vegetable greenhouses and field crops. The heated greenhouse environment has altered the natural extinction–recolonization dynamics of T. ni populations, and allows year‐round persistence in some locations. In addition, the extensive use of the biopesticide, Bacillus thuringiensis subspecies kurstaki (Bt) in some greenhouses has selected for resistance. Here we investigated the genetic structure of T. ni populations in British Columbia greenhouses and in field populations in California and British Columbia using amplified fragment length polymorphisms (AFLP) as related to patterns of Bt resistance. The majority of British Columbia field populations were similar to the California field populations, the potential source of migrants. However populations in two geographic areas with high concentrations of greenhouses showed local genetic differentiation. Some of these populations experienced severe bottlenecks over‐winter and following Bt sprays. Greenhouse populations showed a pattern of isolation by distance and a strong positive relationship between genetic differentiation and levels of Bt resistance. These patterns indicate that greenhouses that sometimes support year‐round populations of T. ni and the ensuing strong bottlenecking effects following winter cleanups and Bt application cause genetic differentiation of T. ni populations. Long distance migrants to field populations contribute to genetic homogeneity of these.  相似文献   

15.
1. We examined the temporal and spatial heterogeneity of zooplankton in lake surface waters during the spring of 3 years in Lake Washington, U.S.A., a large lake with a high production of sockeye salmon fry. 2. We show large within‐season and among‐year variation in the horizontal distribution of temperature, chlorophyll a concentration, and zooplankton in the lake. The main pattern, a delay in zooplankton population increase from the north‐ to the south‐end of the lake, recurred in each year and was persistent within each spring. 3. The delay is primarily caused by the development of a temperature gradient during spring warming, as cold mountain water enters the south end of the lake, while warm water enters the north end via a river draining a nearby lake. Climate factors, such as air temperature and precipitation during winter and spring, appear to influence the extent of the delay of zooplankton increase. 4. If the climate continues to warm, the temporal disconnection in zooplankton development between lake areas immediately influenced by cold river inflow and areas that are influenced by spring warming may increase in magnitude. Thus, the different areas of the lake may not contribute equally to fish production.  相似文献   

16.
This study was designed to investigate spatial and temporal variation in Gelidium canariensis populations at two shores in northern Gran Canaria during two years. Spatial scales ranged from some hundred meters (distance between shores), 10 to 30 m (distance between plots) to less than 3 m (distance between quadrats). Gelidium individuals were defined as distinct Gelidium clumps. The results show a significant difference in size of clumps between shores, but not on the smaller spatial scales. No significant temporal variation was found. There was no significant temporal or spatial variation in standing crop or density (counts made in quadrats where Gelidium was present, rather than counts for the total shore). Sporophytic and gametophytic clumps were also distinguished by identifying reproductive structures in the field. The total proportion of sporophytes was larger than the proportion of gametophytes, but at a smaller scale there could be a shift in dominance. The survival rate of clumps was similar between shores with a mean survival rate of 85%, but there was a significant difference in recruitment between shores. The results indicate a stable population structure. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

17.
Zooplankton samples were collected monthly at three stations in Ogochi Reservoir during 1980, and the temporal and horizontal variations in the density of dominant taxa were evaluated by a standard 2-way ANOVA with random effects. The analysis revealed that horizontal is greater than temporal variation in the warm water season (> 18 °C), whereas temporal variation is greater in the cold water season (< 18 °C). Horizontal heterogeneity of the zooplankton community found in the warm water season seems to be associated with differences in site-specific conditions.  相似文献   

18.
《Journal of Asia》2014,17(3):369-373
Glutathione S-transferases (GSTs) are one of the major detoxification enzymes involved in insecticide resistance. In this study, optimized methodology for GSTs purification and localization in two-dimensional gel electrophoresis is shown on the pollen beetle. Specifically, the GST proteins were purified using GSTrap 4B column, and the protein profile of the supernatant before purification was compared with the unbound fraction post-purification via two-dimensional gel electrophoresis (2D-E). The identity of these localized protein spots was confirmed by MS analysis and further analyzed by NanoLC-ESI-QUAD-TOF-MS/MS protein identification. Results indicate that 2 out of 5 protein spots were GSTs with region for class Delta and Epsilon subfamilies similar to other insects; however, the remaining 3 spots did not show any match in the current NCBInr. Both Delta and Epsilon class GSTs are specifically involved in insecticide resistance and their relatively high abundance in the 2D-E map suggests that these enzymes could play a role in the resistance of Meligethes aeneus to the most commonly used pyrethroids. The approach applied in this study for the specific localization of GSTs in 2D-E can be used for similar analyses in other organisms.  相似文献   

19.
The invertebrate assemblages of the River Lambourn and its tributary, the Winterbourne stream, were investigated as part of a broad ecological study prior to water resource development in the catchment. The longitudinal distribution of the invertebrate fauna within the Winterbourne stream was examined in detail and supporting data for the R. Lambourn revealed that the upstream intermittent section of each water course had an invertebrate assemblage which was distinct from the fauna downstream where flow was permanent. Within the perennial zone taxon richness tended to increase downstream.A one-year programme of monthly quantitative sampling on five distinct biotopes (Ranunculus, Berula, Callitriche, gravel and silt) at two contrasted sites (shaded and unshaded) was undertaken in the lower perennial of the R. Lambourn below the confluence with the Winterbourne. On each study site, the taxon richness, numerical abundance and biomass of invertebrates were significantly higher on the three macrophytes than on gravel and silt. There were also statistically significant seasonal changes in the biomass of invertebrates on each site. Estimates of total biomass of invertebrates per site revealed a late spring peak (May/June) and a late autumn (November/December) peak, neither of which coincided with the summer peak biomass of macrophytes. This suggested that, in the lower perennial, the level of food resources (epiphytic algae in late spring and fallen tree leaves plus decaying macrophytes in autumn) rather than available habitat, were a major influence on population levels for most of the year.Quantitative sampling of each biotope on each site continued in June and December only for a period of 8 years (1971–78), during which time the river experienced a minor drought (1973) and a severe drought (1976). The Chironomidae showed a strong positive response to conditions of low flow in June of 1973 and 1976, when exceptionally high densities of larvae were recorded. Although further between-year differences were recorded in several other major components of the invertebrate fauna, which may have been related to conditions of low discharge, they did not have long-term consequences for the fauna in the lower perennial of the R. Lambourn.In contrast, in the upper perennial, the prolonged drought of 1976 resulted in the loss of wetted perimeter and macrophytes, coupled with deposition of silt, all of which had deleterious effects on the invertebrate assemblages. The following year, despite a normal discharge regime and the removal of silt, some submerged macrophytes were slow to return to their pre-drought condition. In the intermittent section, the drought of 1976 resulted in the total loss of flow for a 16 month period instead of a more typical four month period of water loss.Thus, chalk streams encompass within a single system both stable and extreme hydrological regimes which offer unique opportunities for investigating the processes of community formation and maintenance.  相似文献   

20.
鼎湖山不同自然植被土壤动物群落结构时空变化   总被引:21,自引:2,他引:19  
2001年10月~2002年8月采用大型改良干漏斗和手拣法对鼎湖山鼎湖山南亚热带典型常绿阔叶林、河岸常绿阔叶林、山地常绿阔叶林、针阔混交林、沟谷常绿阔叶林和灌木草丛6种自然植被类型土壤动物群落结构时空变化进行初步调查。结果表明,蜱螨目(A carina)和弹尾目(Co llem bo la)为6种自然植被常年优势类群,缨翅目(T hysanoptera)、鞘翅目(Co leoptera)、膜翅目(Hym enoptera)和双翅目(D iptera)幼虫则为常年常见类群。土壤动物群落类群和个体数量的消长规律分别是:10月=6月=8月>4月>2月=12月和4月>10月>6月>8月>2月>12月。土壤动物个体数量总数依次为南亚热带典型常绿阔叶林>河岸常绿阔叶林>山地常绿阔叶林>沟谷常绿阔叶林>针阔混交林>灌木草丛;不同月份、不同植被类型以及不同月份和不同植被类型之间土壤动物群落的组成具有较大变化,组成差异极显著(F=5.63,α=0.0001;F=11.08,α=0.0001;F=2.97,α=0.0001),不同类群之间个体数量差异极显著(F=102.38,α=0.0001),但月份间类群数差异不显著(F=0.50,α>0.05)。多样性分析表明,类群多样性和均匀性指数除南亚热带典型常绿阔叶林、山地常绿阔叶林12月最高外,其它则2月最高,优势度指数则相反;山地常绿阔叶林土壤动物群落多样性指数和均匀性指数最大,针阔混交林则最小。  相似文献   

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