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1.
诱导抗性作为一种新的植物抗性类型,在防御植食性昆虫的取食和产卵方面具有很大的潜力。该项研究在室内采用选择性方法,观察了分月扇舟蛾幼虫对不同处理的杨树叶的取食选择行为。用虫害叶喂食2~3龄幼虫48 h,测定其营养效应,分析了喂食虫害叶对分月扇舟蛾的幼虫发育历期、蛹重、羽化率等生长发育的影响。利用生化方法测定了杨树叶片虫害后营养物质和次生物质的变化。结果表明:虫害叶对分月扇舟蛾表现为忌避作用;机械损伤叶不影响对寄主的选择性。分月扇舟蛾取食虫害叶后幼虫的发育历期延长、蛹重增加、羽化率降低,可溶性糖含量下降,单宁和黄酮含量增加。  相似文献   

2.
Insect herbivores can become extensive invaders if they are able to undergo host expansions onto widely-grown agricultural host plants. An important yet unresolved question is whether all herbivore populations are equally able to utilize new host plants or if populations may be geographically structured, that is only a subset has the potential to undergo a host range expansion and become widely invasive. We examined if derived and ancestral geographic populations of L. decemlineata or Colorado potato beetle, varied in host preference and performance on both wild (Solanum rostratum) and cultivated (Solanum tuberosum) host plants. Sampling from six different North American regions (3 ancestral and 2 derived), we performed two full-factorial experiments to test for differences in host preference, acceptance, and performance on S. rostraum and S. tuberosum. Our results reveal the development of new (cultivated) host associations within pest populations of L. decemlineata following its geographic expansion. Pest beetles (i.e., Vermont populations) discriminated less between host plants and grew faster than all other beetle population on both host species. The Vermont beetles also developed faster on leaves than all other populations. The greater general preference, acceptance, and performance of Vermont beetles on all host types underscores the virulence of the pest form of the beetle and may help to explain the absence of pest incidence within the ancestral regions of L. decemlineata.  相似文献   

3.
In order to determine their effects on growth and mortality of instar II Hypsipyla grandella (Zeller), larvae were fed with leaf disks taken from shoots of susceptible species (Cedrela odorata L. and Swietenia macrophylla King) scions grafted onto resistant ones (Khaya senegalensis Desr. A. Juss and Toona ciliata M. Roem.), from their reciprocal grafts, and from both intact and autografted plants. In addition, crude leaf extracts from the susceptible and resistant plants, as well as from C. odorata grafted onto T. ciliata plants, were tested on C. odorata leaf disks. Mortality was evaluated 2, 10, and 25 days after starting the bioassay. Leaf area consumed and weight gain per larva were assessed 2 days after starting bioassay. Time to reach pupation, pupal weight and length 1 day after pupation, and time to adult stage and appearance of wings were determined at the end of the bioassay. Plant species significantly affected mortality (P ≤ 0.04) throughout the test. Eighty to 100% of larvae fed leaf disks from intact T. ciliata and its autograft, or C. odorata onto T. ciliata and its reciprocal graft died in the first 2 days of evaluation. All other factors measured, except pupal weight and length, were also affected (P ≤ 0.01) by the leaf disks. Intact resistant plants and reciprocal grafted plants reduced leaf consumption and caused larval weight loss. Larvae fed on K. senegalensis grafted onto S. macrophylla extended by 8 days the time to pupa and to adult stages and induced abnormal wing formation compared to larvae fed intact leaves of C. odorata. Crude extracts from resistant plants equally affected larval survival and performance compared to crude extract from C. odorata grafted onto T. ciliata plants, and these extracts were more detrimental to larvae than those from susceptible species. This study demonstrated that grafting borer-susceptible species on resistant rootstocks can affect the survival and performance of instar II H. grandella larvae.  相似文献   

4.
Between 2010 and 2014, symptoms of a shot hole disease were observed on cherry laurel (Prunus laurocerasus L.) trees and shrubs in parks and other public plantings in Belgrade, Serbia. Ten symptomatic leaves were collected from each of the diseased plants and the associated fungus isolated and identified using multigene phylogenetic analyses and asexual morphological characters. The pathogen was identified as Neofusicoccum parvum. The same symptoms were produced when the pathogen was inoculated on test plants. To the best of our knowledge, this is the first report of N. parvum causing shot hole disease on P. laurocerasus.  相似文献   

5.
Pathogen occurrence was studied in 16?099 adult specimens of 10 different bark beetle species, which live associated on Norway spruce (Picea abies (L.) Karst.). Beetles (mainly Ips typographus L. and Pityogenes chalcographus L.) were collected from 6 different localities in Austria (4 secondary spruce stands and 2 natural forest type stands, 9 sampling plots in total) in elevations between 400?m and 1600?m. Various viral, protozoan, and fungal pathogens could be diagnosed with a light microscope in the examined beetles. Numerous pathogen species were known from former studies, some pathogens were totally new or could be found in a new host species beside their type host. The most dominant pathogen species were Protozoa, Gregarina cf. typographi, Malamoeba cf. scolyti, and Chytridiopsis cf. typographi. Over the whole investigation period, the highest pathogen diversity with eight pathogen species was found in I. typographus. Differences were observed in the pathogen complex of each beetle species from the different collection sites and in different years of investigation. Several species showed an overlapping in their host range and infected various bark beetle species. Furthermore, pathogen occurrence and prevalence differed in bark beetles from 4 different sampling plots in an area (one locality) within a distance of a few kilometres.  相似文献   

6.
The present paper describes new symptoms on Eucalyptus spp. in Central Italy associated with the fungal pathogen Pestalotiopsis biciliata. This fungal species has been previously recorded in Italy on grape associated with fruit rot. Artificial inoculation trials on leaves confirmed the pathogenicity of the fungus to Eucalyptus camaldulensis. P. biciliata is included in the list of Pestalotiopsis spp. responsible for leaf disease on eucalypts worldwide.  相似文献   

7.
The Palaearctic leaf beetle Chrysomela lapponica usually feeds upon willows in the northern region of its occurrence. However, in Central Europe, some populations are known that have specialised on birch. In this study, we investigated the significance of other herbivores occurring together on the same host plants as possible exploitative competitors of C. lapponica. Two populations were studied: a population from Finland specialised on the willow Salix borealis, and a population from the Czech Republic, specialised on the birch Betula pubescens. Abundances of folivorous and suctivorous insects on both host plants were recorded at both population sites. The willow leaf beetle Phratora vitellinae was the most abundant herbivorous insect at both study sites on willow. A field study was conducted to examine the effects of P. vitellinae on the performance of C. lapponica. The presence of P. vitellinae larvae on the same twig upon which C. lapponica larvae were feeding did not affect increase of body weight in C. lapponica larvae. Thus, the high resource availability of both willows and birches suggest that interspecific competition is unlikely to be a selection factor driving the evolution of host shift in C. lapponica.  相似文献   

8.
We used standard isolation protocols to explore the endophytic fungal communities in three tissue types of two dominant orchids (Bulbophyllum neilgherrense and Vanda testacea) of the Kaiga forest ofthe Western Ghats. We surface sterilized and assessed 90 segments ofeach orchid for the occurrence and diversity of endophytic fungal taxa.The 118 fungal isolates were obtained from root, bulb and leaves of B.neilgherrense, consisting of 17 anamorphic taxa (range, 10 15 taxa) with 1.3 fungal taxa per segment (range, 1.2 1.4 taxa). Four taxa (Aspergillus flavus, A. niger, Penicillium sp. and morpho sp. 1) belonged to the coregroup (11.1% 32.2%). The relative abundance of A. flavus and morpho sp.1 was more than 10%. A total of 130 fungal isolates from roots, stems and leaves of V. testacea yielded 20 anamorphic taxa (range, 11 15 taxa)with 1.4 fungal taxa per segment (range, 1.4 1.5 taxa). Aspergillus flavus,A. niger, A. ochraceus, Gliocladium viride, Penicillium sp. and morphosp. 1 belonged to the core group. Relative abundance exceeded 10% for A. flavus, A. niger, and morpho sp. 1. The Simpson and Shannon diversity indices were higher in leaf than root or bulb/stem of both orchids.Jaccard’s similarity coefficient was higher between root and leaf in both orchids (56.3% 60%) than between other pairs. Our study revealed thatthe endophytic fungal assemblage and diversity of B. neilgherrense and V.testacea of Kaiga forest of the Western Ghats were relatively similar between orchids and their tissues.  相似文献   

9.

Improving drought tolerance of container seedlings of Japanese larch is of high importance to afforestation. We hypothesized that adequate nitrogen (N) and limited water supply would increase the tolerance of container seedlings to water-deficit stress, circumventing photoinhibition, by means of (i) enhanced photosynthetic capacity with higher leaf N and (ii) decreased water loss from leaves with lower biomass allocation into aboveground parts. Container seedlings of Japanese larch were grown under the treatment combinations of adequate (+?N: 300 mg N container?1) or limited (??N: 150 mg N container?1) N and adequate (+?W: daily irrigation) or limited (??W: twice-a-week irrigation) water. Then, seedlings were subjected to a progressive drought treatment. Higher leaf N was observed in container seedlings grown under?+?N and???W. During progressive drought, lower stomatal conductance and net photosynthetic rate were observed in leaves with higher leaf N at a given predawn leaf water potential. Furthermore, the maximum efficiency of PSII photochemistry (Fv/Fm) was lower in leaves with higher leaf N, suggesting that higher leaf N might impair intrinsic tolerance to drought at the leaf level contrary to expectations. Conversely,???N and???W seedlings with lower shoot biomass delayed soil drying as a whole-plant response via a reduction in leaf transpiration, leading to delayed photoinhibition as indicated by a decline in Fv/Fm. To circumvent stress at the initial stage of water deficit, lower leaf N via limited N regime and smaller shoot biomass driven by limited N and water regimes would be important.

  相似文献   

10.
A poorly known chrysomelid beetle, Chrysolina fastuosa (Scopoli) has been found in a strikingly great number on black horehound (Ballota nigra L.), a soft caulescent plant belonging to the Lamiaceae family. B. nigra can be found from April to August commonly on roadsides, along walls or at the border of gardens and orchards in Hungary and continental Europe. It can be called a minor weed. The glistering tiny adults that feed voraciously on leaves cause apparently significant damage. The subsequent investigation, which focuses on the number of feeding individuals and the loss of plant tissue, showed 1–24 beetles on a plant and the consumed leave surface which amounted to 8–94%. The repeated damage assessment, a week later showed a significantly unimportant increase in the number of individuals but a significant 20–31% increase in the plant surface loss. According to the literature, Ch. fastuosa has been found in association with other Labiatae plants such as Galeopsis pubescens Besser, Lamium album L. and Urtica dioica L. (Urticaceae). Thus, considering its efficiency mentioned above, it could be used to augment and maintain its populations as a biological control agent for these weeds. However, taking into consideration the growing importance of the production of medicinal plants among which Lamiaceae species are numerous, Ch. fastuosa can cause damage that cannot be neglected.  相似文献   

11.
花绒寄甲在甘肃地区越冬情况和耐寒能力调查   总被引:1,自引:0,他引:1       下载免费PDF全文
The Asian long-horned beetle, Anoplophora glabripennis is a polyphagous xylophage native to Asia. This beetle is the most serious pest in the Three-north Areas of China. Dastarcus helophoroides plays an important role in biological control of the Asian long-horned beetle. In order to determine the probability of introducing this natural enemy to control A. glabripennis in the northwest of China, the overwintering survival of D. helophoroides in north China is a most important issue which should be understood. The overwintering place and survival of D. helophoroides were investigated respectively. The supercooling points of overwintering and laboratory strains of this parasitic beetle were assayed. The results indicated that most of this parasitic beetle chose the long-horned beetle pupa cell and the gallery as their overwintering place. A small proportion of them completed their overwintering process beneath the bark. Over 50% proportion of this beetle can complete the overwintering process successfully. Furthermore, the cold tolerance of overwintering strain was much stronger than that of the laboratory strain. These findings suggested that D. helophoroides can successfully accomplish the overwintering process in northwest of China. This might provide a support for introducing D. helophoroides to control the Asian long-horned beetle in these places.  相似文献   

12.
为探讨感染欧美杨新型溃疡病的中林46杨植株干部病斑中真、细菌优势种类,本研究对河南省濮阳市中林46杨健株、病株染病组织的可培养真菌、细菌优势种群进行了分析。结果表明:健康树皮样品分离真菌优势种群均为Alternaria alternata,染病株样品优势种群均为Fusarium solani,而且其菌株数量占所分离菌株总数的百分比均在85%以上;而在健康株3个处理中分离的细菌优势种群种类不同,仅Microbacterium在健株3个处理树皮样品中均有分布,但染病株3个处理树皮样品中的细菌优势种群均为Lonsdalea quercina,其菌株数量占所分离菌株总数的百分比均在67%以上。以上结果表明:中林46杨发病以后,F.solani和L.quercina分别变成了真菌和细菌的优势种群。  相似文献   

13.
14.
To better understand pathogen/herbivore interactions and landslide regeneration, percent leaf area lost to disease and herbivory on two Puerto Rican trees over a 1-year period was sampled. Cecropia schreberiana saplings lost from 1 to 3% leaf area to pathogens and from 1 to 7% to herbivores. For Inga vera, both sapling and seedling losses to pathogens were minimal, but Inga herbivory losses reached 25% for saplings and 34% for seedlings. The most common fungi on Cecropia leaves were species in the genera Phoma and Phyllosticta, and on Inga leaves was Colletotrichum gloeosporioides. Percent survivorship after 1 year in the field varied among species and life-form (46% for Cecropia saplings, 15% for Inga saplings, 0% for Inga seedlings). There were no effects of pathogens or herbivores on survivorship or growth, but increased levels of herbivory did significantly correlate with total phenolics and condensed tannins in both Inga seedlings and saplings. For both seedlings and saplings of two trees on the neotropic island of Puerto Rico: (1) leaf herbivory was modest and leaf losses to pathogen disease were small; (2) these mechanisms did not affect survivorship or growth; (3) a neotropical tree (I. vera) displayed increased levels of secondary chemicals in its leaves, correlated with increased levels of insect herbivory.  相似文献   

15.
Consistent data demonstrate the positive response of sap-sucking insects to water-stressed plants, but there is a lack of information about the performance of chewing species, including whether their responses vary according to their feeding specializations. We tested the hypothesis that herbivores with distinct feeding strategies and host specialization will respond differently to two plant conditions, i.e. water deficit and kaolin treatment, where the latter is used to reduce abiotic and biotic plant stressors. We determined the development and reproduction of four major cotton pest species with different feeding strategies (chewing and sap sucking) and with specializations ranging from monophagous to polyphagous using well-watered or water-stressed cotton plants, which were treated or not treated with kaolin. Three chewing (lepidopteran) species, Alabama argillacea (Hüb.), Heliothis virescens (Fabr.) and Chrysodeixis includens (Walk), as well as one sap-sucking species, Bemisia tabaci (Gen.), were used as models. The neonate larvae of all three chewing species exhibited lower survival when fed the leaves of water-stressed plants. In addition, the neonate larvae fed leaves from water-stressed and kaolin-treated plants did not complete their development or they exhibited low survival. Older larvae also exhibited significantly lower survival on kaolin-treated plants. The effects on life history traits were more obvious in monophagous chewing species compared with polyphagous species when fed leaves from water-stressed plants. The performance of B. tabaci was superior on water-stressed and untreated kaolin plants. Thus, water-stressed and kaolin-treated plants negatively affected all chewing species, whereas water-stressed plants only positively affected the sap-sucking species.  相似文献   

16.
The transgenic expression of Aspergillus xyloglucanase cDNA (AaXEG2) with 35S promoter in the leaves of open field-grown poplars was studied. The level of xyloglucan in the transgenic poplars was decreased to 15–16% in the non-fertile soil (forest-field soil) and to 21–22% in the fertile soil (farming-field soil) compared with that of the wild-type poplars. The leaves exhibited a smaller surface area with more rounded teeth than those of the wild-type plants, similar to the sun leaf variety that was grown in the incubation room and subsequently greenhoused. The majority of total veins with water-conducting vascular bundles were shorter in the leaves of the transgenic poplars than those of the wild type. This decrease in vein length may result from a decrease in xyloglucan during leaf development, from which large numbers of proteins were markedly downregulated in the leaves of the transgenic plants via proteomic analysis. It seems likely that the leaves of the transgenic poplars came to relax the edges of their tooth rather than extend their veins as a result of the loosening of the xyloglucan cellulose networks in the leaves.  相似文献   

17.
Kumar R  Saha A  Saha D 《Fitoterapia》2012,83(1):230-233
A new γ-lactone coumarin, named as excavarin-A, showing antifungal activity was isolated from the leaves of Clausena excavata by bioassay guided fractionation method. The structure was elucidated by spectroscopic data analysis and identified as 7((2E)-4(4,5-dihydro-3-methylene-2-oxo-5-furanyl)-3-methylbut-2-enyloxy) coumarin. Minimum inhibitory concentration (MIC) was determined against fifteen fungal strains pathogenic against plants and human. The least MIC was recorded against the human pathogen, Candida tropicalis and the plant pathogens Rhizoctonia solani and Sclerotinia sclerotiorum. Antifungal activities against the human pathogens, Aspergillus fumigatus and Mucor circinelloides and plant pathogens, Colletotrichum gloeosporioides, Lasiodiplodia theobromae, Fusarium oxysporum and Rhizopus stolonifer were stronger than that of the standard antimicrobials.  相似文献   

18.
Endophytic fungi in leaves and twigs of healthy and diseased beech trees (Fagus sylvatica L.). Endophytic fungi were isolated from surface-sterilized leaves and twigs of healthy and diseased trees. Three fungal species could be isolated frequently: Apiognomonia errabunda, Diaporthe eres and Bisporella sp. D. eres occurred in leaves of healthy trees more frequently, than in those of diseased trees. It has been hypothesized, that less capacity of water and nutrient uptake of diseased trees is responsible for this effect. A mutualistic symbiosis of A. errabunda and D. eres with beech trees is supposed and discussed.  相似文献   

19.
Laurel wilt, caused by the fungus Raffaelea lauricola and transmitted by the exotic ambrosia beetle Xyleborus glabratus, has killed members of the Lauraceae plant family throughout the southeast United States. A series of experiments were conducted to examine the effects of inoculum concentration on the development of laurel wilt in swamp bay, Persea palustris, and avocado, Persea americana. In each experiment, host plants were inoculated with aqueous suspensions of 102, 103, 104 or 105 conidia of R. lauricola, and plants were rated periodically for external symptom development (wilting and foliar dieback). At the end of experiments, plants were rated for internal symptoms of the disease (discoloration of sapwood) and assayed for R. lauricola on a semi‐selective medium. Symptom severity in swamp bay was significantly lower for the 102 treatment than at higher (103–105) concentrations, whereas 102 and 103 conidia caused less disease than 104 and 105 conidia in avocado. At the lowest inoculum concentration, 67% of the swamp bay plants and 20% of the avocados died by the time the respective experiments were terminated. The pathogen was recovered from a high proportion of the symptomatic sapwood of swamp bay (100%) and avocado (94%), and sapwood discoloration and recovery of R. lauricola from inoculated stems of swamp bay were highly correlated with recovery of the pathogen and symptom development in roots. Clearly, swamp bay and avocado are very sensitive to R. lauricola. The ability of only 100 conidia of this pathogen to kill these hosts suggests that few individuals of X. glabratus or other ambrosia beetles that carry low levels of the pathogen would be sufficient to transmit conidia that infect and lead to disease development. The results are also relevant to the development of disease‐tolerant host selections, as they indicate levels of the pathogen appropriate for use in screening plants for disease resistance.  相似文献   

20.
警惕椰心叶甲对香蕉的危害   总被引:2,自引:0,他引:2  
椰心叶甲除危害椰子等棕榈科植物外,还危害香蕉。通过对香蕉叶的取食能够完成世代的繁殖,卵的孵化率为79.6%,幼虫的成活率为61.3%。既然椰心叶甲能通过取食香蕉叶完成世代繁殖,就证明其已对香蕉树生长产生威胁,应高度关注其对香蕉的危害。  相似文献   

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