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R. G. Freitas R. F. Alfenas L. M. S. Guimarães J. L. Badel A. C. Alfenas 《Plant pathology》2019,68(5):869-877
Calonectria leaf blight, caused by Calonectria pteridis, is currently one of the main foliar diseases in eucalypt plantations in Brazil. In warm and high rainfall regions, the disease can be a limiting factor for eucalypt production when planting susceptible genotypes. The most effective method for controlling this disease in the field is the use of resistant genotypes, which requires knowledge of the genetic variability and aggressiveness of the pathogen population for effective deployment of plant resistance. This work evaluated the genetic diversity and aggressiveness of C. pteridis populations obtained from infected eucalypt plants in Monte Dourado (Pará state) and Imperatriz (Maranhão state), Brazil. To study the genetic diversity, 16 ISSR primers were tested, five of which amplified polymorphic, reproducible and informative bands. Thirty-one closely related genotypes were identified from 84 isolates studied, indicating that the population has a low genetic diversity. The aggressiveness of seven isolates, selected according to geographic origin and their clustering in the ISSR-based dendogram, was determined by inoculation of a hybrid Eucalyptus grandis × E. urophylla clone under controlled conditions. Disease severity was assessed by both measuring the percentage of plant defoliation and assigning a score according to a diagrammatic scale of symptoms. A high correlation between the two evaluation methods was observed, which revealed significant differences in aggressiveness among the isolates. The diagrammatic scale is recommended for disease evaluation because results are obtained much faster, before the occurrence of severe defoliation. No correlation between clustering in the ISSR-based phylogenetic analysis and aggressiveness was observed. 相似文献
3.
Factors affecting overwintering mortality in the Mediterranean corn stalk borer,Sesamia nonagrioides Lefebvre (Lepidoptera: Noctuidae), were investigated under field conditions in the southeast Mediterranean region of Turkey.
During two consecutive years larvae and pupae were sampled from December to April in maize plots sown on three different dates.
Field-collected larvae and pupae were reared and the emerged parasitoids were recorded. An effect of sowing date on total
numbers ofS. nonagrioides was found with reduced populations in the early sown plots. Larval parasitism did not significantly affect overwintering
mortality.Habrobracon hebetor (Say) (Hymenoptera: Braconidae) caused 11% parasitism and was found only in the first year of the study. Pupal parasitoids
were predominantlyIchneumon sarcitorius caucasicus Meyer,Barichneumon sp. andPimpla spuria Gravenhorst (Hymenoptera: Ichneumonidae) and the parasitism level was 11% in both years of the study. 相似文献
4.
Systemic injection of neem (azadirachtin) was tested in the control of horse chestnut leafminer,Cameraria ohridella Deschka & Dimic (Lepidoptera: Gracillariidae), a pest of horse chestnut trees (Aesculus hippocastanum L.: Hippocastanaceae). Three concentrations, 0.08, 0.15 and 0.25 g of active ingredient (a.i.) per cm of diameter at breast
height (dbh), provided long-lasting insecticidal activity. The 0.15 and 0.25 g a.i. concentrations resulted in 100% pupae
reduction in all generations; the 0.08 g a.i. concentration was effective against the horse chestnut leafminer for at least
23 weeks and led to 70–80% pupae reduction. Treated trees did not lose their leaves before winter. Neem applicationvia injection is cheap, with no environmental hazards, and thus this treatment is recommended for the control ofC. ohridella in horse chestnut trees.
http://www.phytoparasitica.org posting Dec. 19, 2004. 相似文献
5.
Essential oils extracted fromEucalyptus blakelyi (1,8-cineole, 77.5%),Melaleuca fulgens (1,8-cineole, 56.9%) and 1,8-cineole were shown to have fumigant toxicity against different development stages ofSitophilus oryzae. The eggs ofS. oryzae were the most tolerant, followed by pupae, larvae and adults in that order.M. fulgens oil,E. blakelyi oil and 1,8-cineole at 100 μl per liter of air gave, respectively, LT50 values of 16.2, 17.4 and 9.1 h for adults, 31.1, 19.3 and 17.5 h for larvae, 55.6, 75.2 and 39.7 h for pupae, and required
>7 days for eggs. Only 1,8-cineole (200 μl
−1 air) gave a significant egg kill by 7 days and the LT95 was 134.5 h. 1,8-Cineole could be a useful new fumigant.
http://www.phytoparasitica.org posting Oct. 3, 2004. 相似文献
6.
Tachinid parasitoids ofTraumatocampa ispartaensis Doğanlar & Avcı (Lepidoptera, Thaumetopoeidae), which was found to be a new species, were collected from the cedar forests
around Isparta-Kapıdağ. The species found wereBlondelia nigripes (Fall.),Compsilura concinnata (Meig.),Pales processioneae (Ratz.),Phryxe caudata (Rond.),Exorista segregata (Rond.) andCarcelia iliaca (Ratz.). Within the six species of Tachinidae,B. nigripes was the most common one, parasitizing up to 4.6% ofT. ispartaensis pupae.
http://www.phytoparasitica.org 相似文献
7.
The essential oils from rosemary (Rosmarinus officinalis L.) and laurel (Laurus nobilis L.) obtained from Mersin Province in Turkey, were tested for their fumigant toxicity against all life stages of confused
flour beetle (Tribolium confusum du Val.). GC-MS analysis showed that 1,8-cineole was found to be the major component of both rosemary and laurel essential
oils. Vapors of rosemary and laurel essential oils were toxic to all life stages ofT. confusum. Only 65% mortality of the eggs was achieved when exposed to a dose of 172.6 mgl
−1 air of rosemary essential oil at the longest exposure period (144 h); at the same dose, the pupae were the most resistant
stage, with LT90 (lethal time) value of 120.2 h. The adults were the most resistant stage to laurel essential oil, with LT90 value of 77.2 h. On the basis of LT90 values, tolerance of the life stages ofT. confusum to rosemary and laurel essential oils was, in descending order: pupa < larva < adult, and larva < adult < egg < pupa, respectively.
Based on the concentration × time (Ct) products (g hl
−1), rosemary essential oil was more toxic than laurel to the adults and larvae ofT. confusum. However, laurel essential oil was more toxic than rosemary to the eggs and pupae. Since these essential oils need such high
Ct products to obtain complete mortality ofT. confusum compared with the most commonly used commercial fumigants, it would be impossible to use them on their own as a commercial
fumigant against stored-product insects. 相似文献
8.
Joanne Fouché-Weich Stéphane Poussier Danielle Trigalet-Demery Dave Berger Teresa Coutinho 《Journal of General Plant Pathology》2006,72(6):369-373
Ralstonia solanacearum is a known bacterial pathogen of eucalypt and potato plants in Africa. A survey was undertaken to detect this pathogen in
eucalypt plantations in South Africa, the Democratic Republic of Congo, and Uganda. Numerous bacterial strains were isolated
from trees with symptoms typical of bacterial wilt, but only seven were positively identified as R. solanacearum. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique, based on the hrp (hypersensitive response and pathogenicity) gene region was used to determine and group the biovars of these R. solanacearum strains. The eucalypt isolates and one potato isolate formed a biovar 3 cluster, whereas the two other potato isolates formed
a cluster that corresponded to biovar 2. Amplified fragment length polymorphism (AFLP) analysis confirmed these clusters.
Therefore, PCR-RFLP can be used as a reliable diagnostic technique to enable researchers to rapidly identify the pathogen. 相似文献
9.
为有效控制柳毒蛾Leucoma salicis对沙柳Salix psammophila的为害,深入了解柳毒蛾幼虫和蛹的种群空间结构,利用地统计学方法分析了不同立地条件下不同年龄沙柳林地中柳毒蛾幼虫和蛹的空间分布特性。结果表明:柳毒蛾幼虫和蛹的数量在沙丘顶部最多,每丛沙柳中分别为17.03±5.15和15.24±5.26头,与在沙丘底部的数量分布差异不显著;在多年生沙柳林地内的数量分布最多,每丛分别为20.31±2.39和18.02±3.19头,与2年生沙柳林地内的数量分布差异极显著。沙丘顶部多年生沙柳、沙丘顶部和底部2年生沙柳上柳毒蛾幼虫和蛹的空间分布均呈聚集条带状分布,聚集斑块由聚集中心区域向四周逐渐减小;沙丘底部多年生沙柳上幼虫和蛹的空间分布为随机分布;不同样地内,柳毒蛾蛹和幼虫在沙柳上的空间分布相同。 相似文献
10.
V. Skuhravy 《Anzeiger für Sch?dlingskunde》1998,71(5):81-84
Cameraria ohridella was recorded first in 1985 in Macedonia. It gradually expanded to north and west and at present it is a serious pest of Horse
ChestnutAesculus hippocastanum in the Czech Republic, having been established at about 80 localities. There are 4–5 overlapping generations with sizes of
the larvae of 0.4–4.0 mm. The larva develops inside the leaf tissue in the upper parenchym layer of the leaflet and causes
a mine, the size of which is broadened with growing larva. First adults start to fly at the end of April. After mating the
females lay single eggs on the leaves. Larval development lasts 25–30 days followed by the prepupa I and II. The latter spins
a cocoon in which the pupa of the last generation hibernates. The development from L4 to the prepupa lasts for 3–6 days at
22°C. During the summer it is possible to find all larval and prepupal stages in attacked leaves. FourAesculus species:A. parviflora Walk,A. carnea Haey.,A. glabra Walk andA. indica J. Hobb. were found to be resistent toC. obridella. A. lutea H. J. was liftle andA. pavia L. was heavily attacked. The parasitization ofC. o. larvae was very low. Only 2 parasites were found in 1500 mines in the first and second generation ofC. o., and 40 parasites in 1000 mines of the fourth and fifth generation. The highest mortality takes place in moths, eggs and
young larvae. It was found in all 4 generation that there were i. m. 50 eggs/leaflet from which i. m. 3 hibernating pupae
resulted. Supposing 2 moths (1♀, 1♂)/leaflet emerged in spring which produced 50 eggs (75 eggs/♀—33% moth mortality), the
density of eggs in the first generation after hibernating being the same as in the last (fourth) generation before hibernating.
As to the whole populations density in this case we can calculate as following: 3 pupae/leaflet on the tree=3000 pupae/leaflets
pro m2 on the soil=2000 emerging moths pro m2=50,000 moths (25,000 ♀♀) pro tree (namely 25 m2 projecting area of the tree crown×2000 moths).
相似文献
11.
Thirty-five strains ofVerticillium lecanii which originated from different hosts and geographical locations were tested as potential biocontrol agents against silverleaf
whitefly,Bemisia argentifolii Bellows & Perring. All strains were tested for their pathogenicity to third-instar nymphs. Several isolates which exhibited
high pathogenicity to nymphs were also tested against eggs, pupae and adults ofB. argentifolii. Eggs were found to be immune to infection, but mortality of hatching nymphs reached 95–98%. The rate of hatching nymphs’
infection depended on the age at which the eggs were inoculated and the strain’s virulence. Mortality of nymphs recorded on
day 4 after inoculation varied from 0.5±0.3% to 83±2.4%; that of the control ranged from 2.5% to 10.2%. The most virulent
strains, with LT50 ranging between 3.2 and 3.8 days, were isolated from aphids in Israel and probably have a similar origin. The pathogenicity
ofV. lecanii strains to pupae 6 days after inoculation varied between 59± 12.1 % and 72.5± 13.1 %, as compared with natural mortality
of 13.5±4%. The maximum adult mortality caused byV. lecanii strains was between 34.1±5.1% and 52.6±3.8%. 相似文献
12.
The effects ofCitrus reticulata Blanco (tangerine) foliage age on larval survival and performance of the lappet mothStreblote panda Hübner (Lepidoptera: Lasiocampidae), a polyphagous Mediterranean species, were studied. Larvae were reared under controlled
laboratory conditions on young and mature excised leaves of tangerine. Survival, duration of development, and post-ingestive
indices of larval growth were determined. Mature leaves significantly reduced survivorship of early instar larvae. Larvae
which were fed on mature leaves grew more slowly and were less efficient at utilizing plant biomass and nitrogen than larvae
fed on young leaves. Growth rates were 30% higher on young leaves, overall efficiency of conversion of ingested food was greater
also, as consequence of an increase of 46% in the assimilation efficiencies, whereas the efficiency of conversion of digested
matter into larval biomass was similar in both food treatments. The rate of consumption of biomass was higher in mature leaves,
but that of nitrogen was similar, indicating that mature leaves restricted growth primarily by restricting the efficiency
of utilizing this nutrient. The nitrogen utilization efficiency was reduced more than 20%, and the relative accumulation rate
of nitrogen was suppressed 30% for larvae on mature leaves, which may explain the protracted development time of larvae fed
on mature leaves. Survival was consistently higher when larvae were fed with young leaves although no differences were found
for mature larvae or pupae. No differences were found in pupal mass (a fecundity correlate) between food treatments. Our results
confirm the bibliographic records ofCitrus spp. like host plants ofS. panda in Spain, but also suggest that much variation must be expected in the temporal and spatial incidence of this insect, depending
upon the cultivated species, associated plant phenology and management techniques employed in the culture.
http://www.phytoparasitica.org posting Aug. 28, 2005. 相似文献
13.
The red spider miteTetranychus evansi (Acari: Tetranychidae) Baker and Pritchard was recorded for the first time in Greece, in the area of Tympaki (south-central
Crete) onSolanum nigrum. T. evansi is a pest of crops of the family Solanaceae, which are grown extensively in Crete. The species identification was based on
both morphological and molecular data. The second internal transcribed spacer was PCR amplified and sequenced in samples from
Crete. Sequences were compared with the sequence ofT. evansi from Brazil and with the ITS2 sequences (retrieved from GenBank) of the two closely related tetranychid species most commonly
found in Greece,Tetranychus turkestan andTetranychus urticae. 相似文献
14.
Citrus leafminer Phyllocnistis citrella and its parasitoids in Sargodha region of Pakistan 
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下载免费PDF全文 In order to identify the parasitoids of Phyllocnistis citrella, an important pest of Citrus, the larvae and pupae of this pest were collected from Citrus reticulata Blanco orchards in the Sargodha region of Pakistan. The parasitoid species were identified, and their abundance was recorded. A total of two species were identified: Citrostichus phyllocnistoides (Narayan) (Hymenoptera: Eulophidae) and Cirrospilus ingenuus Gahan (Hymenoptera: Eulophidae). Out of a total of 409 P. citrella larvae and pupae collected, 73 C. phyllocnistoides and 39 C. ingenuus adults emerged. This paper documents the species and the abundance of the parasitoids associated with P. citrella in the Sargodha region of Pakistan. 相似文献
15.
Rodrigo G. Freitas Pollyane S. Hermenegildo Renan S. Cascardo Lúcio M. S. Guimarães Samuel A. Santos Jorge L. Badel Poliane Alfenas-Zerbini Acelino C. Alfenas 《Plant pathology》2021,70(7):1708-1718
Bacterial wilt caused by Ralstonia solanacearum is a serious disease of eucalypt in humid and high temperature areas worldwide. Spreading of the bacterium in the field or to other nurseries occurs mainly by symptomless infected plant material. The use of pathogen-free propagating material as well as planting of resistant genotypes are currently the only strategies used for disease control. Therefore, a reliable and sensitive method for detection of low titres of R. solanacearum in infected plant tissue is essential for the success of management programmes. In this work, we adapted an efficient intercalating dye-based real-time PCR protocol to detect the bacterium in symptomless eucalypt plants as well as to investigate its movement in eucalypt clones CLR172 and CLR371, which exhibit resistant and susceptible phenotypes, respectively. We found that the bacterium translocates acropetally and basipetally in inoculated but symptomless cuttings of the resistant clone, as in cuttings of the susceptible clone displaying symptoms. Nevertheless, a smaller concentration of bacterial DNA was detected in tissues of the resistant clone. Mature biofilms occluding the xylem vessels were present in the susceptible clone whereas only single cells or small aggregates were observed in the resistant clone. This work contributes to improve our knowledge of the colonization process of R. solanacearum in eucalypt clones with different levels of susceptibility and to understand how the defence mechanisms against bacterial wilt in Eucalyptus work. Our findings could aid in the selection of the most resistant eucalypt clones to be used in wilt disease management programmes. 相似文献
16.
N. P. Caires L. M. S. Guimarães P. S. Hermenegildo F. A. Rodrigues J. L. Badel A. C. Alfenas 《Plant pathology》2020,69(3):549-558
Dieback and wilt caused by Erwinia psidii is an emerging disease that has been causing considerable damage in eucalypt plantations. Because it is a recently emerged disease, several aspects of the bacterial interaction with its host still remain to be elucidated. In this work, we studied the E. psidii colonization and biofilm formation in eucalypt tissues by specific detection using PCR and scanning electron microscopy (SEM). The results indicate that the bacterium is able to translocate in stem tissue mainly acropetally, although movement in the basipetal direction was also observed to a lesser extent, always through the xylem. No colonization of phloem tissues was observed. In addition to colonizing the xylem, E. psidii colonized the parenchymatous tissue. The bacterium formed cell aggregates enveloped by fibrillar material that evolved into complex, well-structured biofilms in stem and leaf tissues. In contrast, no biofilm formation was observed on abiotic surfaces. These observations suggest that biofilm formation plays an important role in the elicitation of dieback and wilt symptoms caused by E. psidii on eucalypt plants. This study not only shows ultrastructural aspects of the E. psidii communities but also tissue damage in eucalypt plants that was associated with the presence of bacterial aggregates and formation of tyloses. 相似文献
17.
S. Navarro 《Phytoparasitica》1978,6(2):51-58
The relationship between different oxygen tensions and exposure times producing 95% mortality, and loss in weight of three stored-product insects at 54% R.H. and 26°C, was determined.Ephestia cautella (Wlk.) pupae andTribolium castaneum (Herbst) adults reacted in a similar pattern: the lower the oxygen concentration, the shorter the exposure time needed to produce 95% mortality, and the higher the rate of loss in weight. The response ofSitophilus oryzae (L.) adults was different: there was greater sensitivity at 1% oxygen than at the lower or higher levels of oxygen tested. A relationship was demonstrated between low oxygen tensions (0–5%) and the relative humidity of the environment for producing a lethal atmosphere forE. cautella pupae andT. castaneum adults. 相似文献
18.
The study deals with the tachinid parasitoids ofAncyrosoma leucogrammes (Gmelin) (Heteroptera: Pentatomidae):Clytiomya dupuisi Kugler,Clytiomya sola (Rondani) andGymnosoma clavatum (Rohdendorf) (Diptera: Tachinidae). All species are recorded for the first time as parasitoids ofA. leucogrammes, andC. dupuisi was reared for the first time from a host. The parasitization rates ofC. dupuisi on adults ofA. leucogrammes varied from 7% to 9% between 1994 and 1999.C. sola andG. clavatum were reared in only small numbers.
http://www.phytoparasitica.org posting July 10, 2003. 相似文献
19.
Diafenthiuron (CGA 106 ’630), a thiourea, was sprayed prior to a 48-h infestation by adult females of the sweetpotato whiteflyBemisia tabaci Gennadius, on cotton seedlings under greenhouse conditions; it subsequently suppressed strongly progeny formation of the
whitefly, resulting in approximately 50% progeny formation relative to control at 5 mg a.i./l. When the different development
stages were separately sprayed directly, the larval stage was the most susceptible, resulting in 50% and 90% mortality of
2nd instars at concentrations of 6.5 and 49.2 mg a.i./l, whereas the LC50 values of adults and pupae were 23 and 45 mg a.i./l,
respectively. A mild (30–35%) reduction of egg hatch was obtained at a range of 5–125 mg a.i./l. Thus the potency of diafenthiuron
against various stages was in the order larvae > adults > pupae > eggs. Diafenthiuron exhibited a low vapor phase toxicity
and had no translaminar effect when tested on first instars ofB. tabaci. The high potency of diafenthiuron against whiteflies described herein, against aphids and mites, as stated in the literature,
and against some lepidopterous pests, render this compound an important insect control agent for pests of cotton and other
crops. 相似文献
20.
Peach fruit fly (PFF), Bactrocera zonata, is one of the most dangerous pests of horticultural crops worldwide. This pest spends part of its life cycle in the soil as pre-pupae and pupae. Therefore, the effects of soil type and soil water content levels (SWCLs) on pupal mortality rates of the PFF were studied in an attempt to use soil moisture as an abiotic management strategy for this pest. The effect of clay, loamy, and sandy soils with SWCL of 0, 10, 25, 50, 75, 90, and 100% of field capacity on three ages of PFF pupae (newly formed, 4- and 7-day-old pupae) were studied. Results demonstrated significant effects of SWCLs on pupal mortality rates of PFF. SWCL was the factor with the most remarkable effect (48.47%), meanwhile soil type had a feeble effect (0.65%). Newly formed pupae were more susceptible to SWCL levels than 7- and 4-day-old pupae. Results suggest that sustaining SWCL near 100% of field capacity significantly (p?=?0.000) suppressed PFF population; therefore it could be an important component of Integrated Pest Management against this insect species. 相似文献