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1.
The development time and parasitization rate ofDiaeretiella rapae (M’Intosh) onBrevicoryne brassicae (L.) feeding on differentBrassica cultivars was studied in the laboratory at 20°C. The shortest development time from egg to adult parasitoid was 11.6 days on cabbage cv. ‘Yalova 1’ and the longest was 12.1 days on turnip cv. ‘Antep’ and rapeseed cv. local variety. Females lived significantly longer than males on the host plants used in the study. Females and males had the shortest longevity on rapeseed at 11.1 and 5.1 days, respectively. The highest percent parasitism ofB. brassicae byD. rapae was found on cabbage (40.20%), and the lowest was recorded on turnip (32.64%). Our results demonstrate that parasitism rate could be influenced by the plant quality, probably due to the nutritional status of the aphids or to toxic compounds ingested through the plant. Cabbage, cauliflower and broccoli were found to be suitable plants for the parasitoid, considering the development time of pre-adults, and the parasitization rate ofD. rapae onB. brassicae. http://www.phytoparasitica.org posting Jan. 23, 2007.  相似文献   

2.
A study was conducted to determine the feasibility of using sclerotia ofSclerotinia sclerotiorum for producing conidia ofConiothyrium minitans in liquid culture. The medium (SST) was made of water containing 2.0, 1.5, 1.0 or 0.5% (w/v) ground sclerotia ofS. sclerotiorum and 100 μgl −1 thiamine hydrochloride (HCl). One ml of conidial suspension (2 × 107 conidia ml−1) ofC. minitans LRC 2534 was inoculated into 100 ml of SST medium or control (thiamine HCl in water) and incubated at 20 ± 2°C on a shaker at 200 rpm. Subsamples were removed periodically and examined under a compound microscope. Conidia in the SST media germinated within 24 h, developed into branched hyphae within 48 h, produced pycnidia after 3–4 days, and the pycnidia released mature conidia after 7 days. Production of conidia varied with the concentration of sclerotia in the SST medium. It was lower (3.6 × 106 conidia ml−1) at 0.5% but higher (1.2 × 108 conidia ml−1) at 2%. The new conidia were viable and the colonies developing from them showed the original morphological characteristics. It was concluded that using SST liquid medium as a substrate for mass production of conidia ofC. minitans has potential for use in commercial development of this mycoparasite as a biocontrol product. http:www.phytoparasitica.org posting Jan. 23, 2007.  相似文献   

3.
Willows (Salix spp.) are beneficial as a potential source of renewable energy, riparian barriers and riverbank control, yet are considered invasive weeds when they clog watercourses and lead to erosion and flooding. Interactions between willow rustMelampsora epitea (Thüm.) (Uredinales: Melampsoraceae) and leaf beetlePhratora spp. (Coleoptera: Chrysomelidae) feeding damage have an impact on effective pest management and biological control. The present study investigated the effects of(a) prior mechanical leaf damage on rust development, and(b) rust infection on beetle feeding under laboratory conditions for different time intervals and levels of damage. Willow rust infection significantly reduced the amount of leaf area consumed by beetles. The result was similar when a compatible or an incompatible rust pathotype was sprayed ontoSalix viminalis (L.) ‘Mullatin’ plants. There were no overall significant effects of mechanical damage on rust development, although the lowest level of rust infection was found with the incremental damage treatment. There were, however, differences of significance for leaf position and damage status, with damaged leaves at all positions having fewer pustules and a smaller pustule area than the corresponding undamaged leaves. There was no detectable effect of possible volatile emissions from crushed willow leaves on rust infection and development, although the volatile compoundcis-3-hexenyl acetate significantly reduced pustule diameter and overall pustule area. The results are discussed in terms of the implications for pest management and biological control. Corresponding author http://www.phytoparasitica.org posting April 6, 2003.  相似文献   

4.
The susceptibility ofThaumetopoea wilkinsoni larvae toBacillus thuringiensis (Bt) formulations was screened in 2003 and 2004. Eggs and larvae were collected from pine forests in 11 geographical locations in Israel. Larval mortality bioassays were conducted with commercial formulations (Delfin WG, Dipel DF and Foray 48B) at concentrations ranging from 0.001% to 0.1%. Significant differences in susceptibility toBt were recorded among populations that were treated withBt intensively, frequently, or never. The mortality recorded in a population that was never treated withBt was twice that in an intensivelyBt-treated population. The correlation between susceptibility toBt and the possible resistance to the microbe is discussed. http://www.phytoparasitica.org posting Jan. 31, 2007.  相似文献   

5.
The variation and distribution of virulent phenotypes ofBremia lactucae Regel, the causal agent of lettuce downy mildew, were studied during 2002–2003 in lettuce fields (Lactuca sativa) in Israel. A total of 21 isolates ofB. lactucae were collected from nine locations in three regions of Israel: Galilee, the Coastal Plain, and the Shefela. The isolates were examined for the presence of 21 virulence factors (v-factors) and their combinations with differential sets of lettuce lines/varieties. There were clear differences in v-factors, and a broad diversity of v-phenotypes among the isolates was found. Although 17 different v-phenotypes and 20 v-factors were detected, a composite of similar v-phenotypes generally occurred between isolates within the three regions. They differed mostly in the presence or absence of only a few v-factors. The Coastal Plain region averaged the highest virulence complexity (0.63), significantly different from that of the Shefela (0.45) and of Galilee (0.4). Comparison of the IsraeliB. lactucae isolates that were tested in this study with data of other countries showed that factor v18, which did not occur in the Israeli populations, was detected only in Czech and German pathogen populations. http://www.phytoparasitica.org posting Dec. 21, 2006.  相似文献   

6.
Information on persistence ofBacillus thuringiensis (Bt) is needed to improve the microbial pest management programs against the pine processionary mothThaumetopoea wilkinsoni in pine forests in Israel. The persistence of the microbe under natural conditions of rain and sunlight was evaluated and is documented here for the first time. Pine saplings were sprayed with three commercialBt products, Foray 48B, Delfin WG and Dipel DF, all used at 32,000 IU mg−1 in a formulation with 1% (w/v) of condensed milk. In experiments conducted in November and December of 2004, the saplings were either exposed to rain and sunlight or were sheltered to avoid these environmental factors. The lowest rainfall recorded in the 8-day experiments was 16.5 mm (test 2) and the heaviest was 71.1 mm (test 1). Solar irradiation ranged from 9.4 to 10.9 MJ m−2. The minimum temperature was close to 10°C and the maximum was less than 23°C. Needles of the treated saplings and their controls were sampled after 0, 1, 5 and 8 days, and were fed to 1 st or 2 nd instar larvae. Dipel DF persisted better than Delfin WG and still retained its initial activity of 80–100% mortality on day 8 at low rainfall (test 2). Dripping ofBt from upper to lower branches was quantified with the larval bioassays. The milk formulation proved to be an effective rain-fasting adjuvant. http://www.phytoparasitica.org posting May 4, 2007.  相似文献   

7.
Ophelimus maskelli (Ashmead) (Hymenoptera: Eulophidae), an invasive species in the Mediterranean area that occurs naturally onEucalyptus camaldulensis at Wagga Wagga in New South Wales, was studied in Israel on the same host plant. The most distinctive characteristic ofO. maskelli as compared with other congeners is the presence of only a single seta on the submarginal vein.O. maskelli shows a clear tendency to oviposit in developed, immature leaves, and it prefers to oviposit on an area of the leaf blade near the petiole. The female lays an average of 109 eggs when maintained on water alone. The egglaying distribution tended towards aggregation, and the same tendency has also been observed within and among trees. The wasp prefers to attack the lower canopy. The gall diameter ranged from 1.2 to 0.9 mm, and gall density from 11.5 to 36.0 galls cm−2, respectively. The typical color of the gall appeared as soon as third instar larva developed. Galls on shaded leaves remained green or greenish-yellow, whereas those that were exposed to the sun were reddish.O. maskelli produces three generations per year in Israel. High flight occurs among the spring generations, starting in early March. The wasps were attracted to green sticky plates much more than to the other tested colors. Heavy galling byO. maskelli results in premature shedding of the leaves, soon after the emergence of the wasps. Among the 84 eucalyptus species tested, the following 14 species were found to be suitable hosts:E. botryoides, E. bridgesiana, E. camaldulensis, E. cinerea, E. globulus, E. gunii, E. nicholii, E. pulverulenta, E. robusta, E. rudis, E. saligna, E. tereticornis andE. viminalis. This study focused on morphological and development characters that can clearly distinguishO. maskelli fromOphelimus eucalypti Gahan, and on examining the effect of crossing between eucalyptus species on the development possibilities of the wasps. Also considered were the effect of the food on adult survival, the competition between the eulophid gall makerLeptocybe invasa Fisher & LaSalle andO. maskelli, the heavy damage inflicted on eucalyptus, and the health problems and nuisance to people caused by the wasp near heavily infested trees during the mass emergence of adults. http://www.phytoparasitica.org posting Dec. 5, 2006.  相似文献   

8.
The employment of formulatedBacillus subtilis for peanut seeds (Arachis hypogaea cv. ‘Shulamit’) counteracted the destructive effects of the seedborne pathogenSclerotium (Athelia)rolfsii on the nodulation, leghemoglobin and nitrogenase activity of peanuts. Moreover, the changes in crop vigor index, total nitrogen content and survivability of bothRhizobium spp. andB. subtilis have been related to compatibility and even an occasional synergism between them. http://www.phytoparasitica.org posting Nov. 12, 2006.  相似文献   

9.
A total of 101Verticillium dahliae isolates were recovered from cotton plants at 57 sites in the Aegean region of Turkey between 2003 and 2004. Isolates were tested for vegetative compatibility by observing heterokaryon formation among complementary nitrate-nonutilizing (nit) mutants. Forty-six isolates were assigned to VCG 1, 12 to VCG 2A, 33 to VCG 2B and four to VCG 4B. The remaining six isolates could not be tested for vegetative compatibility because of their inability to yieldnit mutants. All isolates recovered were tested for pathogenicity on cotton cultivars Acala SJ-1 and Deltapine 15-21 by the stem-injection method. The isolates of VCG 2 and 4B, irrespective of their origin, induced weak to severe symptoms on cotton and were similar to the previously described cotton non-defoliating pathotype. In contrast, all cotton isolates of VCG1 caused severe foliar symptoms, stunting, defoliation and often death. This is the first report on VCG 1 ofV. dahliae in Turkey. http://www.phytoparasitica.org posting May 4, 2007.  相似文献   

10.
Tomato chlorosis virus causes yellow leaf disorder epidemics in many countries worldwide. Plants of Physalis ixocarpa showing abnormal interveinal yellowing and plants of Physalis peruviana showing mild yellowing collected in the vicinity of tomato crops in Portugal were found naturally infected with ToCV. Physalis ixocarpa and P. peruviana were tested for susceptibility to ToCV by inoculation with Bemisia tabaci, Q biotype. Results confirmed that ToCV is readily transmissible to both species. The infection was expressed in P. ixocarpa by conspicuous interveinal yellow areas on leaves that developed into red or brown necrotic flecks, while P. peruviana test plants remained asymptomatic. Infected plants of both P. ixocarpa and P. peruviana served as ToCV sources for tomato infection via B. tabaci transmission. This is the first report of P. ixocarpa and P. peruviana as natural hosts of ToCV.  相似文献   

11.
During a 6-year study, grapevine propagation materials and young grapevines were analysed to evaluate the presence of internal wood discolouration and the occurrence of fungal species involved in Petri disease. The intensity of wood discolouration increased with the ageing of the plants. The maximum incidence of dark streaks was observed in the rootstock while necrosis originating from buds or nodes were notably present in the trunk and cordon of older vines. In contrast, the highest levels of brown-red halo symptoms, defined as discoloured areas around the pith, were recorded in the early growth stages. Phaeoacremonium spp. and Phaeomoniella chlamydospora were usually isolated from the rooted-grafts and the 3-year old plants, respectively. The number of infected grapevines increased with age. Most of the P. chlamydospora strains were isolated from dark streaks or dots, while Phaeoacremonium spp. were detected in brown-red halo symptoms and other symptomatic or asymptomatic wood. The greatest incidence of the two fungal taxa was recorded in the lower parts of the grapevine, including the roots and rootstock.  相似文献   

12.
The development and reproductive rates ofTetranychus cinnabarinus Boisduval (Acari: Tetranychidae), the carmine spider mite, were studied on two strawberry cultivars (Fragaria ×ananassa Duch.; ‘Camarosa’ and ‘Sweet Charlie’) at three NaCl concentrations, 1760, 2400 and 3040 mgl −1, and control. The effects of NaCl application on the contents of plant nutrients, chlorophyll, proline, peroxidase activity (POX) and proteins were assessed. On Camarosa,T. cinnabarinus had a faster development rate with applications of NaCl than without, except for female development at the highest salinity level. The total development time of females increased with the NaCl concentration, whereas total development time of males decreased. The oviposition period and female longevity on Camarosa was significantly longer in the control than with NaCl, whereas daily and total fecundity were significantly higher at all NaCl concentrations than in the control, except for total fecundity at the lowest salinity level. The total development time, oviposition period, female longevity, daily and total fecundity on Sweet Charlie did not differ significantly between NaCl salinity levels and the control. The intrinsic rate of natural increase (r m ) on Camarosa and Sweet Charlie were significantly higher with NaCl than in the control. However, the contents of Na, Cl, P, chlorophyll, proline, POX and protein in the two strawberry cultivars changed depending on NaCl concentration. On the other hand, the K and N contents were not affected significantly by NaCl salinity. http://www.phytoparasitica.org posting Nov. 19, 2006.  相似文献   

13.
The silverleaf whiteflyBemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae) [also known as strain B of the sweetpotato whiteflyB. tabaci (Gennadius)] is a major pest of tomatoes due to both feeding damage and transmission of plant viruses. Certain wild species ofLycopersicon have demonstrated high levels of resistance to the pest. Greenhouse studies were undertaken to quantify the effects on whitefly behavior and mortality of individual, resistant plants selected from three accessions ofL. pennellii (Corr.) D’Arcy (LA 1340, LA 1674 and LA 2560), five accessions ofL. hirsutum f.typicum Humb. & Bonpl. (LA 386, LA 1353, LA 1777, PI 127826 and PI 127827) and one accession ofL. hirsutum f.glabratum C.H. Mull. (PI 126449). In no-choice experiments, fewer adults settled on leaflets of the wild species and deposited 75–100% fewer eggs compared to the cultivated tomato,L. esculentum Mill. Adult mortality ranged from 77–100% on wild accessions but was only 1% onL. esculentum. Most dead adults were trapped in glandular trichome exudates. The effects of these resistant accessions onB. argentifolii were mechanically transferable by appressing the trichome exudates onto the leaves of the susceptible tomato, indicating an association between the factors mediating the resistance and the glandular trichomes. Laboratory studies evaluated the repellent, fumigant and residual toxic effects of representative constituents of trichome exudates onB. argentifolii adults by using selected concentrations and probit analyses. RC50 values (estimated concentration to repel 50% of the adults) and LC50 values for fumigant and residual toxicity indicated that 2-tridecanone had low levels of repellent and residual toxicity activity; that 2-undecanone had high levels of repellent and fumigant activity; and that ginger oil (composed, in part, of sesquiterpene hydrocarbons) had high levels of repellent and residual toxicity activity. These studies suggest that multi-factor resistance exists in wild tomato germplasm. By combining genetically the observed chemical constituents of resistance into a single germplasm, the resulting resistance may be more difficult forB. argentifolii to overcome. http://www.phytoparasitica.org  相似文献   

14.
An introductory study was conducted to investigate the pyrethroid resistance ofHelicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) strains in Turkey, collected from cotton fields in the Adana and Antalya provinces, through two different synthetic pyrethroid insecticides: lambda-cyhalothrin and esfenvalerate. In addition, the roles of glutathioneS-transferases (GSTs) in this resistance mechanism were analyzed. It was found that whereas resistance ratios for lambda-cyhalothrin (LD50 levels) were 3- and 98-fold increased in the Adana and Antalya strains, respectively, esfenvalerate ratios were 3.3- and 92.3-fold increased in the Adana and Antalya strains, respectively, with respect to the susceptible strain. Furthermore, Adana and Antalya strains showed 2.4- and 2.9-fold higher GST activities than the susceptible strain, respectively. In the Antalya field strain, the minor increase in GST activity compared with the resistance levels implies that GSTs may be not greatly involved in this resistance. It also provides evidence that they could not be the only metabolic mechanism responsible for resistance to lambda-cyhalothrin and esfenvalerate inH. armigera from Turkey. http://www.phytoparasitica.org posting Nov. 16, 2006.  相似文献   

15.
Leaves of Xanthium strumarium infected with downy mildew were collected in the vicinity of a sunflower field in southern Hungary in 2003. Based on phenotypic characteristics of sporangiophores, sporangia and oospores as well as host preference the pathogen was classified as Plasmopara angustiterminalis. Additional phenotypic characters were investigated such as the size of sporangia, the number of zoospores per sporangium and the time-course of their release. Infection studies revealed infectivity of the P. angustiterminalis isolate to both X. strumarium and Helianthus annuus. Inoculation of the sunflower inbred line, HA-335 with resistance to all known P. halstedii pathotypes, resulted in profuse sporulation on cotyledons and formation of oospores in the bases of hypocotyls. Infections of sunflower differential lines often led to damping-off. Molecular genetic analysis using simple sequence repeat primers and nuclear rDNA sequences revealed clear differences to Plasmopara halstedii, the downy mildew pathogen of sunflower.  相似文献   

16.
The infestation intensity of the ectoparasiteErythraeus ankaraicus Saboori, Cobanoglu and Bayram (Acari: Erythraeidae) onAsymmetrasca (=Empoasca) decedens (Paoli) (Homoptera: cicadellidae),Aphis gossypii Glov. (Homoptera: Aphididae) andThrips tabaci Lind. (Thysanoptera: Thripidae) in cotton was investigated during the 2004 and 2005 growing seasons in Aydin Province, TurkeyE. ankaraicus was recorded for the first time onA. decedens leafhopper nymphs during the early growth stage of cotton. Parasitism ofE. ankaraicus on leafhopper nymphs during the first week of July 2004 was 68.9%, whereas in the middle of July 2005 — when mite populations peaked — it reached only 15.1%. Parasitism of the leafhopper was not observed from the middle of the season onward (August to October).  相似文献   

17.
The genera ofMicrogaster Latreille 1804 andHygroplitis Thomson 1895 from China are presented systematically in this paper. Thirty-two species ofMicrogaster and three species ofHygroplitis are known in China. Diagnosis, character variation, distribution and host of each species among the two genera are presented, including its host and distribution. Keys to the species ofMicrogaster andHygroplitis are given. http://www.phytoparasitica.org posting Dec. 19, 2006.  相似文献   

18.
An attempt was made to achieve low environmental risk control of insect pests using sublethal concentrations of insecticides, enhanced by the effect of high temperatures (>25°C). For each of the insecticides imidacloprid, abamectin, pirimicarb and azadirachtin, the lethal and sublethal concentrations were determined for the green peach aphidMyzus persicae (Sulzer) (Homoptera: Aphididae) and its predator, the lady beetleHarmonia axyridis (Pallas). The lady beetle was more tolerant of all four insecticides, as well as of high temperatures below 40°C, compared with the prey. The joint action of sublethal concentrations of insecticides and high temperatures was investigated to determine the sublethal concentrations and temperatures that would be effective in controlling the aphids, but not detrimental to the beneficial lady beetle. The results suggested a synergistic effect of sublethal insecticide concentrations and high temperatures against the green peach aphid.  相似文献   

19.
Serial passage experiments (SPE) of a Barley yellow dwarf virus-PAV (BYDV-PAV) isolate were performed on Zhong ZH and TC14 wheat lines to evaluate the durability of their resistance to BYDV. At different passage numbers (from the 2nd to the 114th), biological properties of the produced isolates were recorded either by monitoring infection percentages and virus titers of the first 3 weeks of viral infection or by measuring their impact on yield components. Statistical analyses using the area under pathogen progress curves and the area under concentration progress curves demonstrated that these two resistant lines induce, after only a few passages, a selection of variant(s) with significantly modified infection abilities. Isolates resulting from SPE performed on these lines induced important decreases of yield components. These results indicate that the use of Zhong ZH and TC14 lines in BYDV-resistant breeding programmes should be approached with caution.  相似文献   

20.
The Eucalyptus gall waspOphelimus maskelli (Ashmead) (Hymenoptera: Chalcidoidea: Eulophidae: Ophelimini) and its introduced parasitoidClosterocerus chamaeleon (Hymenoptera: Chalcidoidea: Eulophidae: Entedoninae) are recorded for the first time in the Mediterranean and Aegean Regions of Turkey. Some morphological characters of adult and larva ofO. maskelli and larva ofC. chamaeleon are described and illustrated. Distributions of the two wasps collected in Turkey are given. Results indicate that the biological control agent,C. chamaeleon, has spread over 1,300 km in the 16 months since its initial release.  相似文献   

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