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1.
A supplementary research on Russian wheat aphid (= RVA), Diuraphis noxia (Kurdj.) between 1998-99 documented the pest distribution all over the Czech republic already. RVA abundance was proved to be significantly area-dependent within the state. The banker areas are in southern Moravia (district Znojmo, the frontier area near Austria) up to central Moravia. The determined RWA distribution area is much broader than presumed on grounds of climatic characteristics.The abundance of RVA generally decreases from the SE to the NW and N direction, as well as with the increasing altitude within the area.The highest altitude a.s.l. of RWA occurrence in the crop was 762 in. The re-classified main expansion route was determined to follow two directions (sourcing from Hungary and Austria) to southern-central-northem Moravia, and to southern Bohemia and further on to the central Bohemian lowland. The field information indicated the development of preference of RWA for barley.  相似文献   

2.
A part of the territory of the Czech Republic represents the up-dated northern limit of distribution (status 1997) which the Russian wheat aphid (=RWA),Diuraphis noxia (Kurdj.) has reached during its expansion from the southeast to central Europe. The newly defined area is classified as one of the adventive routes which may be derived from the main expansion of RWA from its native home (central-western Asia) into the broader Mediterranean area. Distribution and its history, and ecology (life-cycle, host plants, seasonal history, both native and introduced natural enemies) of RWA are presented on ground of field evidence and trials obtained in 1995–1997 in the Czech Republic. The origin of RWA, its distribution and establishment in the target area, as well as prognosis of its further expansion, are reviewed and discussed. Steps and approaches to RWA detection in the crop, as well as some notes on its management, are added.  相似文献   

3.
An analysis of the Russian wheat aphid (RWA) (Diuraphis noxia Kurdj.), overpopulated due to extraordinary weather conditions (2000) in the Czech Republic, enabled the identification of several within-field situations ouside of the routine approach. This group, classified as within-field refugium, includes variation due to field relief, some injuries caused by the use of machinery, the unharvested field margins and, last but not least, the volunteer plants. Differences between the RWA populations in these situations and the normal grove are presented and recommended to be taken into consideration in the research on RWA population dynamics and movement.  相似文献   

4.
Two hot and dry weather periods during mid-spring and early summer caused severe drought-stress to barley groves in many districts of the Czech Republic in 2000. Although not generally taken into consideration as an injury-increasing factor, the Russian wheat aphid (=?RWA), Diuraphis noxia (Kurdj.), was discovered to contribute significantly to injury in the ripening stage of spring barley as well as to the substantial decrease of yield (up to 30?–?40?% of the calculated mean, in some districts). RWA increased considerably not only in the lowland banker areas but also in the higher altitudes, values in the latter case then manifesting those found in the lowland banker areas in the previous years.  相似文献   

5.
Flight patterns of migrant alate Russian wheat aphids (=RWA),Diuraphis noxia (Kurdj.) during its expansion from the south-east to Central Europe were determined. Samples were taken by Rothamsted-type suction air traps in Hungary (one location, 1990–1997) and in the Czech Republic (5 locations, 1994–1998). The results document a progressive expansion of RWA, and population variation in the individual years and periods of the season. A comparison of the evidence on RWA in the individual years since its detection in Hungary and in the Czech Republic supports the presumption on the occurrence of an expansion route from the south-east (Turkey) to Central Europe. This expansion is classified as an adventive route of the over-all expansion that has covered the whole West-Mediterranean (South Europe, North Africa).  相似文献   

6.
The Russian wheat aphid,Diuraphis noxia (Mordw.) has been detected in southern Moravia, the Czech Republic in June, 1995. Its location is related to its incidence in central Hungary. The further predicted area of distribution covers the grain-maize growing districts of southern Moravia (Czeck Republic), neigh-bouring parts of Austria, southern and south-eastern parts of the Slovak Republic. The aphid is classified as a species expanding to the north from its mediaterranean area of distribution, apart of extensive areas (North to South Americas, S. Africa, expected in Australia) which it has covered thorugh accidental introductions and further spread over the world.  相似文献   

7.
Bemisia tabaci is a species complex, of which the B and Q biotypes are globally distributed. B. tabaci feeds on more than 600 plant species including cotton, which is one of the main crops in Pakistan. In this study, the biotypes/haplotypes of B. tabaci populations collected from cotton plants in Pakistan, China, and Egypt were identified, and their phylogenetic relationships were investigated. None of the populations from Pakistan or Egypt belonged to the B or Q biotype: all 16 samples from Pakistan belonged to haplotype “PCG-1” and it is a group of unresolved populations all from Pakistan, while all three populations from Egypt belonged to unresolved haplotype “ECG.” The three populations from China belonged to the B biotype. Phylogenetic analysis indicated that the PCG-1, ECG, and B biotypes clustered into different clades even though they share the same cotton plant species as their host. The association between the outbreaks of cotton leaf curl disease and the occurrence of the PCG haplotype of B. tabaci in Pakistan is discussed.  相似文献   

8.
以20个云南松天然群体为对象,SSR分析表明云南松遗传变异主要存在于群体内,各群体间的遗传多样性水平差异不显著。基于SSR分子标记遗传多样性分析,根据Nei's遗传相似度,采用逐步聚类优先取样法,分别对初始群体、遗传多样性保护单元和剩余群体进行比较、t检验,以此评价遗传多样性保护单元的代表性。结果表明,利用该方法抽样的群体能很好地代表初始群体的遗传多样性,按30%的群体抽样,等位基因数、有效等位基因数、Shannon's信息指数和期望杂合度的保留率分别达到初始群体的98.03%、105.36%、103.99%和105.56%。保护单元的遗传多样性均高于剩余群体,抽样群体组成的遗传多样性保护单元的效果较好。  相似文献   

9.
Insect samples were collected from the canopy of 24 willow short rotation coppice (SRC) sites on farmland in Britain and Ireland in 1995. The blue willow beetle Phratora (= Phyllodecta) vulgatissima (L.) (Coleoptera: Chrysomelidae), previously identified as the main defoliating pest of this crop, was recorded from 13 of these at varying levels of abundance. Data describing aspects of the environment at each site were also collected. These data were used to create potential explanatory variables for a regression analysis of beetle abundance. This analysis indicated that P. vulgatissima were most likely to occur and were more abundant at older willow sites on clay soils and at sites that bad certain free-living willow species growing nearby. Within sites, most willow clones sampled contained P. vulgatissima, although two, Salix burjatica‘Germany’ (‘Aquatica Gigantea’) and Salix mollissima‘Q83’ (Salix triandra × Salix viminalis), were avoided. Chrysomelid pest avoidance and clonal resistance could form part of an integrated pest management strategy for SRC crops.  相似文献   

10.
Cool and wet weather in some periods of the season generally supressed the RWA (Diuraphis noxia Kurdj.) populations in the Czech republic in 2001. However, some sites manifested population levels ranging out of the population mean stated per area, and these sites were also apparently responsible for respective peaks of alate aphids sampled by suction traps. An analysis of these sites determined them to be attributed to some poor quality barley fields in a warmer area of the state. RWA is known to vary in all-over populations in different years, and the year 2001 illustrated its capability of its surviving even unfavourable periods and seasons, remaining well-established in the area.  相似文献   

11.
Conspecific and heterospecific associations of aphid parasitoids (Hymenoptera, Braconidae, Aphidiinae) were used to determine the interactions between crops forming the main arable crop ecosystem (wheat, alfalfa, isogenic and [Bt Bacillus thuringiensis] transgenic maize) in an irrigated area in Catalonia, Spain. Species composition and instars of parasitized aphids (mummies) were used to detect the parasitoid population movements between the crops and proved interactions (alternation) between the crops, including transgenic maize. Parasitoid interactions were species-dependent, appearing in the movements between alfalfa-wheat-maize in the individual species. Aphidius ervi Hal., A. rhopalosiphi DeSt.-Perez, A. uzbekistanicus Luzh., Lysiphlebus testaceipes (Cress.) and Praon volucre (Hal.) were classified as key-stone species in the target agroecosystems in the area. No differences were found in aphid-parasitoid associations on Bt transgenic maize and isogenic maize for aphid species composition and associated parasitoid guild.  相似文献   

12.
The parasitoids (Hymenoptera, Braconidae, Aphidiinae) of the cowpea aphid, Aphis craccivora Koch, were investigated throughout two far distant provinces, Tehran and Sistan-Baluchestan. Colonies of the cowpea aphid were collected from different host plants and reared under laboratory conditions until the parasitoids emerged. The aphids were parasitized by an expected range of parasitoids. The species were Aphidius colemani Viereck, Lysiphlebus fabarum (Marshall), Lysiphlebus confusus Tremblay and Eady, Lysiphlebus testaceipes (Cresson), Binodoxys acalephae (Marshall), Binodoxys angelicae (Haliday), Praon volucre (Haliday) and Ephedrus persicae Froggatt. L. testaceipes is reported here for the first time in Iran. The most common species was L. fabarum followed by B. acalephae and L. confusus. A key is provided for identification and host plant associations are considered.  相似文献   

13.
The ocurrence of the different cereal aphids (Hom., Aphididae) in Northern German wheat growing areas 1974 and 1975 In July, 1974 and 1975,Macrosiphum avenae (F.) was the most common aphid on cereal fields in Northern German wheat growing areas.Rhopalosiphum padi (L.) was less abundant, whileMetopolophium dirhodum (Wlk.) was found very seldom.R. padi infested field edges only in most cases, while this was not true for all fields infested byM. avenae.  相似文献   

14.
对鸡足山地区4个多星韭种群的染色体进行核型分析与比较,结果表明：多星韭1号和4号种群为二倍体,核型公式为：2n=2x=14-8sm（2SAT）＋6m和2n=2x=14-10m（SAT）＋4sm,多星韭2号和3号种群为四倍体,核型公式为：2n=4x=28-14m（2SAT）＋14sm和2n=4x=28=18m（2SAT）＋10sm。从植株形态、分布、生境、核型等方面分析表明,多星韭核型进化趋势是由二倍体向四倍体进化的,四倍体多星韭二倍化显著。  相似文献   

15.
The thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is among the most important pests of greenhouse crops in Europe and causes considerable damage to commercial rose crops. The usage of pesticides is associated with major problems, and thus the interest of implementing integrated pest management (IPM) for rose crops is increasing. One essential component of IPM is field monitoring/scouting. Growers use information gathered from scouting to select and schedule appropriate control tactics. Thrips populations were surveyed in 2005 and 2006 in a greenhouse planted with roses, Rosa x Hybrida in Southern of France. From April to August, thrips were counted using yellow sticky traps (YST), knock-down techniques [i.e., tapping flower heads (FT)] and actual counts of entire plants. Thrips abundance recorded using YST correlated well with abundance levels determined through FT or actual counts (whole plant). Our results demonstrate that it is accurate to estimate thrips populations using YST in rose crops in greenhouse. Because YST takes at least twice less time than other monitoring methods, it could be used as a valid and easy monitoring technique in further development of IPM programs on roses. The possibility of setting a damage threshold using the data from the YST in the greenhouse is discussed.  相似文献   

16.
Lysiphlebus testaceipes (Cr.), an exotic aphid parasitoid, but widespread along the West Mediterranean and Atlantic coastal areas, was regularly found in the northeastern part of the Iberian Peninsula parasitizing several aphid hosts, inland and in the Pyrenees. It was found that the environmentally induced restriction of available host species together with the opportunistic response and host alternation of the parasitoid contributed to the successful and on-going expansion and establishment of L. testaceipes from the coast to the inland montane areas of the Iberian Peninsula. Also, a comparison of the overall host range of L. testaceipes in several areas of the West Mediterranean/Atlantic (southern France, Spain, Portugal) demonstrated a rapid increase in the host range in these areas.  相似文献   

17.
The rose-grain aphid,Metopolophium dirhodum (Wlk.), is a species living onRosa spp. as winter hosts and Gramineae as summer hosts. Thus, the planting of roses along roadsides and highways may be of importance in connection with the migration of the aphids to cereals. In March 1982 the nymphs hatched from eggs, which were laid in autumn on long shoots. One or two days after hatching they fed on buds in batches up to 15 individuals. Somewhat later they dispersed on the hostplants. The nymphal mortality of the first generation was high, namely about 79%. For further population development the number of fundatrices was less important due to their high reproduction capacity. Nymphs and adults of the first generation often changed their feeding site on the shoots. The specimens of the 2nd and 3rd generation were more stationary and formed dense colonies. The population density drastically increased during the 3rd generation. The development of the aphid populations on the primary host took place during 2–3 generations and lasted until the beginning of June, when the winged forms left the hosplant. In the second generation, i. e. at the beginning of May, the first emigrantes appeared and the size of the aphid colonies increased up to 115 individuals. Most colonies consisted of less than 11 aphids namely 30.9%. Natural enemies were present in large numbers during the end of May when the populations of aphids decreased due to emigration. They did not influence the density of aphid colonies, except the predacious larvae of hover-flies. Trophobiosis between ants and rose-grain aphids was not observed on the primary hostplant.  相似文献   

18.
[目的]明确两种接种方式(自然迁飞和人工挂袋)下角倍蚜虫瘿的数量和分布及其对寄主盐肤木枝叶生长的影响。[方法]在自然迁飞和人工挂袋形成虫瘿的盐肤木林内,按随机区组设计设置样地,在样地内随机选取有虫瘿树和无虫瘿树,分别测量和统计盐肤木及虫瘿的生长指标,采用方差分析虫瘿对盐肤木生长的影响。[结果]在自然迁飞和人工挂袋两种接种方式下,盐肤木单株虫瘿数没有显著差异。但人工挂袋时,单片复叶的平均虫瘿总体积为170.92±14.85 cm~3、小叶总面积为616.26±32.73 cm~2,显著高于自然迁飞形成虫瘿的总体积85.82±9.40cm~3和小叶总面积482.81±28.51 cm~2。表明人工挂袋接种可以增加虫瘿的总体积,从而提高角倍产量;同时,较大体积的虫瘿还促进了盐肤木小叶的生长,使小叶面积增大。[结论]角倍蚜虫瘿对寄主盐肤木的枝叶生长具有促进作用,且这种生长促进与虫瘿的体积呈正相关。与自然迁飞接种相比,人工挂袋接种更能发挥盐肤木的生长和结倍潜力,提高角倍产量。  相似文献   

19.
Parkia biglobosa is an important multipurpose tree from the savanna zone of West Africa. It has been reported to increase soil fertility and crop yields beneath its crown. However, no work has been conducted to determine the role of root symbioses in soil amelioration by this species. The existing reports of nodulation inParkia biglobosa are contradictory and the presence of mycorrhizae is not documented in the literature.Fieldwork was conducted at six sites in Burkina Faso and Nigeria, to investigate the amelioratory effect ofParkia biglobosa on soil fertility and to ascertain the occurence of root symbioses. Soil samples were collected from points close to the trunk, the mid-crown, crown edge and the open areas away from individual trees. The samples were analysed chemically to assess pH, organic matter, nitrogen, phosphorus and potassium content. Root samples were also collected from the field and examined for nodules and for evidence of mycorrhizal infection.The results of the soil analysis showed a significant amelioration for total nitrogen and available potassium with proximity to the tree, but organic matter, available phosphorus and soil pH showed no significant trend. This pattern was similar for all sites. The results also indicated that amelioration of nitrogen and potassium with proximity to the tree increased with tree size.Root nodules were absent from the roots of trees examined in the field, both in Burkina Faso and Nigeria. A pot experiment was set up using the soil collected from beneath the trees and a laboratory grown cowpea miscellany culture as rhizobial inoculum forParkia biglobosa seedlings. The roots of these seedlings also showed no evidence of nodulation. Ectomycorrhizae were not present in roots collected from the field, but endomycorrhizal infection was prolific.A study of root distribution in Burkina Faso suggested that one mechanism for increased soil fertility beneathParkia biglobosa is the widespread lateral root system, which redistributes nutrients from an extensive radius to a concentrated area beneath the crown. The root system is aided in the efficient uptake of nutrients by endomycorrhizae. Other possible mechanisms include interception of dust by the crown and deposition by throughfall and stemflow, defacation by animals beneath the tree and decomposition of leaf litter.  相似文献   

20.
Red wood ants (Formica rufa group, RWAs) are common insects in boreal forests in Fennoscandia, and they build large, long-lived mounds as their nests. RWA mounds are enriched with carbon and nutrients, but little information is available about how they affect root distribution and the nutrient uptake of trees. In this study, we investigated the biomass, biomass density, nutrient concentrations, and amounts of fine (<2 mm) and coarse (>2 mm) roots in RWA mounds, and compared them with those of surrounding forest soil in mixed coniferous stands of different age classes in Finland. Neither fine nor coarse root biomasses differed significantly between the aboveground parts of the mounds and the organic layer of the soil. Root biomass density was lower in mounds than in the organic layer. However, fine root biomass and biomass density were higher in the belowground parts of mounds than in the surrounding mineral soil. Macroelement (N, Ca, K, P, S, Mg) and Zn and Cu concentrations in roots in the mounds were significantly higher than those in the organic layer. Root biomass and biomass density did not differ between stands of different age classes. The results of this study indicate that RWA mounds increase heterogeneity in root distribution in forest ecosystems, and also increase the availability of nutrients for plants that extend their roots inside RWA mounds.  相似文献   

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