bluuebunny/crossref_metadata_2025 huggingface dataset:
Do polyphagous predators help control orange wheat blossom midge, Sitodiplosis mosellana Géhin (Dipt.,Cecidomyiidae) in winter wheat?
Authors: Holland J. M. , Thomas S. R.
Published: March 2003

Abstract: Polyphagous predatory invertebrate populations were manipulated using exclusion techniques in order to examine their impact on Sitodiplosis mosellana Géhin. Experiments were conducted within the framework of the LINK Integrated Farming Systems Project in the UK, which allowed the effect of the predators to be compared between integrated and conventional farming systems. In 1995 and 1996, the exclusion technique indicated that polyphagous predators had little impact on S. mosellana numbers prior to oviposition, but may reduce the number of midge returning to the soil to diapause and thereby help to prevent populations building up in the soil. Sowing date affected ear infestation levels with earlier‐drilled, conventionally farmed plots suffering heavier infestations. A strong correlation was found between the number of larvae per ear and the percentage of ears infested. At 100% infestation there was a mean of 2.8 S. mosellana larvae per ear.
Foraging behaviour and sequential multisensory orientation in the aphid parasitoid,Pauesia picta(Hym., Aphidiidae) at different spatial scales
Authors: Völkl W.
Published: March 2003

Abstract:Foraging females ofPauesia picta,a parasitoid of the conifer aphidCinara pineaon pine, used a variety of host plant or host‐borne cues to find and recognize its aphid hosts. For long‐range detection, females rely mainly on secondary plant compounds to locate potential host plants. In the medium‐range (i.e. on a given host plant), females detected the presence of hosts by encounters with honeydew‐collecting workers of the antFormica polyctenaand by perceiving host‐borne cues. For short‐range detection, after the discovery of an aphid colony,P. pictafemales recognize hosts visually. Subsequent antennal tapping, a tactile stimulus, prevents dispersal of aphids and increases the oviposition success of the parasitoid. The final host acceptance is obviously triggered by signals located in the epicuticle of the host. The results demonstrate the importance of sequential multisensory foraging that correspond to a diminishing distance between the parasitoid and the host.
Notes on the biology and ecology of the parasitoids of the poplar clearwing moth, Paranthrene tabaniformis (Rott.) (Lep., Sesiidae) in Bulgaria. I. Apanteles evonymellae (Bouché, 1834) (Hym., Braconidae)
Authors: Georgiev
Published: March 2003

Aspects of the biology and ecology of Apanteles evonymellae (Bouché), a parasitoid of the poplar clearwing moth, Paranthrene tabaniformis (Rott.), were studied during the period 1987–96. One‐year‐old poplar (Populus spp.) shoots infested with P. tabaniformis larvae were collected during the winter months at 11 localities in Bulgaria and examined in the field and laboratory. Apanteles evonymellae was recorded in all areas studied in Bulgaria. The mortality of P. tabaniformis caused by this parasitoid in various regions of Bulgaria varied from 2.4 to 35.4%; the average for the country was 17.3%. Laboratory observations showed that A. evonymellae is a solitary endoparasitoid of the poplar clearwing moth. It develops in early‐stage (first‐ to fourth‐instar) host larvae and overwinters as a larva in the host. Apanteles evonymellae is bivoltine, but only the second generation is associated with P. tabaniformis. In the field, adult parasitoids of first generation appear in April about 1 month before the emergence of P. tabaniformis. The longevity of A. evonymellae adults is a maximum of 6 days. Therefore, in the spring, A. evonymellae cannot attack neonate P. tabaniformis larvae and must develop in alternative hosts. Prior to their death the parasitized P. tabaniformis larvae construct conical structures, ‘refuges’ of frass and silk threads over the external openings of the larval galleries. Apanteles evonymellae pupates in these refuges after the host’s death. This modified behaviour of the parasitized host larvae probably protects the pupae of A. evonymellae from hyperparasites and predators.
Life history of the predatory mite Lasioseius athiasae (Acari, Ascidae) on various kinds of food substances: a polypeptide analysis of prey consideration
Authors: Abou‐Awad  , Korayem  , Hassan  , Abou‐Elela
Published: March 2003

The predacious ascid mite Lasioseius athiasae Nawar and Nasr was found in association with herbaceous plants, fallen leaves and in debris under deciduous fruit trees. The larvae fed and developed on different prey, such as ‘motile stages of the eriophyid grass mite Aceria dioscoridis (Soliman and Abou‐Awad), eggs of house fly Musca domestica L., nymphs of the two‐spotted spider mite Tetranychus urticae Koch, and eggs of the root‐knot nematode Meloidogyne incognita Chitwood. Eriophyids of grasses caused the immature stages to develop faster than did other prey. During the oviposition period, daily consumtion by a female of L. athiasae was 97 A. dioscoridis, four M. domestica eggs, and 10 T. urticae nymphs. The average number of eggs/female per day was 3.21, 1.63 and 1.26 for the above‐mentioned prey, respectively. A low rate was recorded on M. incognita eggs (0.35). The intrinsic rate of increase (rm) was increased when fed on A. dioscoridis, but decreased on other prey species. The multiplication per generation (Ro) was 44.73 times in a generation time (T) of 17.92 days when fed on eriophyids. The eriophyid grass mite proved to be the more suitable prey. The polypeptide analysis of different prey revealed that A. dioscoridis has the most important contents in both number (11 polypeptides) or total molecular weight (682 kDa).
Effects of different field management systems on the carabid coenosis in oil seed rape with special respect to ecology and nutritional status of predacious Poecilus cupreus L. (Col., Carabidae)
Authors: Langmaack M. , Land S. , Büchs W.
Published: March 2003

It could be shown, that the differences between two carabid populations on rape fields under intensive management and reduced management (50% N‐input, no insecticide application) were not as striking as one might expect. Despite the fact that total individual numbers of the carabid populations, total species numbers, and number of dominant species were clearly higher in the field under reduced management, RENKONEN’s Re showed only a slight difference between the fields with nearly three‐quarter correspondence in dominance structure. The presence of five more carabid species on the field under reduced management is underlined by the low values of JACCARD’s species identity and WAINSTEIN’s Kw index of similarity. On the other hand, according to SHANNON‐WEAVER’s Hs for species diversity and SHANNON’s Es for evenness, the differences between the fields are minor. Even if only the dominant species were taken into account, the similarity between both fields was obvious, despite the fact that in the field under reduced management two more dominant carabid species were found. In both fields, phytophagous Amara similata was the most abundant species. Nevertheless, a special oil seed rape carabid coenosis seems to exist as well, as one was found for cereal crops and for root crops, which might consist of A. similata, Amara aenea, Harpalus affinis, Poecilus cupreus, Pseudophonus rufipes, and Pterostichus melanarius.

For P. cupreus, which was chosen as a typically predacious and beneficial carabid species in oil seed rape, biomass, fecundity and determination of the degree of gut filling also showed no differences for the fields. Even the length of elytrae as an indicator for nutritional situation in the preceding year showed no difference. Only the phenology of P. cupreus showed an obvious shift of the peak in activity‐density in the intensively managed field, to a later date in the season, compared with the field under reduced management. The latter reflects the usual spring peak. No sufficient explanation was found for the peak 4 weeks later on the intensively managed field. It can be assumed that a less sufficient food supply (higher numbers of potential food, e.g. larvae of Meligethes spp. in the field under reduced management), due to insecticide input, or long‐term biocide impact on P. cupreus, or a faster growth of rape plants due to high nitrogen input resulting in a less favourable microclimate on the intensively managed field, was responsible for this later peak in activity‐density.

To conclude, the relations between the predacious carabids, their potential prey, and the abiotic factors in the habitats seem to be much more complicated than assumed. There is a strong hint that the impact of single parameters such as field management influencing the phenology change obviously over the carabids activity period.
Chemosterilant activity of naturally occurring quinones and their analogues in the red cotton bug, Dysdercus koenigii (Het., Pyrrhocoridae)
Authors: Magdum S. , Banerjee S. , Kalena G. P. , Banerji A.
Published: March 2003

The chemosterilant activity of two naturally occurring napthaquinones, plumbagin from Plumbago sp. and juglone from Juglans regia has been evaluated using the red cotton bug Dysdercus koenigii. Their activity were compared with synthetic napthaquinones, menadione, two benzoquinones, 2,6‐dimethyl and 2,3,6‐trimethylbenzoquinone and a hydroquinone 2,6‐dimethylhydroquinone. As far as the authors are aware, the present investigation is the first systematic attempt to investigate the effects of quinones on different aspects of reproduction, namely mating behaviour, fecundity and fertility. All the above types of quinones have revealed adverse effects on the reproduction of D. koenigii, which were topically treated as 1‐day‐old adults with different doses of the compounds depending on their 50% lethality (LD50) values. Analysis of the data revealed a highly statistically significant reduction in the number of eggs, their hatching and further development up to the final instar stage. The sterility index increased with the increase in the dose of any of the above compounds and was highest when both sexes were treated. Among the natural products, juglone induced more sterilizing effects than plumbagin at 5–10 μg/insect. Menadione caused sterility at a very low dose such as 0.5 μg. Of the two benzoquinones, the dimethylbenzoquinone acted at a much lower dose.
Optical brighteners as ultraviolet protectants and as enhancers in pathogenicity of Spodoptera litura (Fabricius) (Lep., Noctuidae) nucleopolyhedrovirus
Authors: Monobrullah MD. , Nagata Masao
Published: March 2003

Seven optical brighteners were tested using diet disc bioassays in the laboratory to determine their effects on the protection and activity of Spodoptera litura (Fabricius) (Lep., Noctuidae) nucleopolyhedrovirus (SlMNPV) against 4th instar S. litura larvae. All brighteners tested were found to be effective UV protectants and five brighteners (Blankophor BBH, Blankophor RKH, Blankophor P167, Blankophor HRS and Tinopal LPW) enhanced viral activity by 5.53–11.08 times. Viral activity was increased with the concentration of brighteners. The time required for the virus to kill larvae was reduced by 24–27% at 1% concentration of brighteners. Some infectivity of the virus was found in the older larvae, which were resistant to SlMNPV, by adding the brighteners. On the basis of data obtained in the present study we discuss the synergistic action of optical brighteners with SlMNPV.
Impairment of reproduction in the red flour beetle, Tribolium castaneum (Herbst) (Col., Tenebrionidae) due to larval feeding on triflumuron‐treated diet
Authors: Parween Selina , Faruki Saiful Islam , Begum Mahmuda
Published: March 2003

The larvae of Tribolium castaneum (Herbst) of different ages were exposed to various concentrations viz., 0.0001, 0.001 and 0.01 ppm of triflumuron up to pupation. The adults were allowed to feed on untreated diet. The preoviposition period, fecundity, egg viability and incubation period of the eggs laid were studied. Triflumuron significantly lengthened the preoviposition and incubation periods (P < 0.001). Fecundity and egg viability were also reduced (P < 0.001) due to the treatment. Both the strains were affected by the treatment.
Comparative life table analysis of Trichogramma bournieri Pintureau and Babault and Trichogramma sp. nr. mwanzai Schulten and Feijen (Hym., Trichogrammatidae) from Kenya
Authors: Haile A. T. , Hassan S. A. , Sithanantham S. , Ogol C. K. P. O. , Baumgärtner J.
Published: March 2003

Abstract:  Egg parasitoids of the genus Trichogramma (Hym., Chalcidoidea: Trichogrammatidae) have been successfully utilized for biocontrol of several lepidopteran pests world‐wide. Trichogramma bournieri Pintureau and Babault and Trichogramma sp. nr. mwanzai Schulten and Feijen, which are native to Kenya and recovered from Chilo partellus eggs, were compared with the aim of evaluating them for field releases in Kenya for the control of lepidopteran pests, particularly Helicoverpa armigera and Plutella xylostella in tomato and kale, respectively. Age‐specific life tables were constructed at the Institute for Biological Control (BBA), Darmstadt, Germany in 1999 using a cohort of 60 mated females each at 26 ± 1°C, 70 ± 10% relative humidity and 16 h light : 8 h dark photoperiod. The adult female performance and population growth statistics with associated standard errors were computed. There was no significant difference in adult longevity between selected strains of the two species. Trichogramma sp. nr. mwanzai showed significantly higher cumulative as well as daily mean fertility (75.97 and 18.11, respectively) compared with T. bournieri (47.83 and 13.24, respectively), and the respective proportion of female progenies were 52 and 72%. The intrinsic rate of natural increase was 0.309 and 0.306, while the net reproductive rate was 35.16 and 31.22 for T. sp. nr. mwanzai and T.bournieri strains, respectively. The study has also shown that there is no significant difference in the intrinsic rate of natural increase and the net reproductive rate between the two native species. In summary, there is difference between the two strains in their parasitization potential but not in population growth potential. Consequently, no preference can be given to one species when selecting for mass rearing purposes. Adult female performance is superior in T. sp. nr. mwanzai than in T. bournieri. Hence, the former strain should receive particular attention in future studies.
Influence of proportion of (4S)‐cis‐verbenol in pheromone bait on Ips typographus (Col., Scolytidae) catch in pheromone trap barrier and in single traps
Authors: Jakuš R. , Blaženec M.
Published: March 2003

Abstract:  The possibilities of increasing catching efficiency of male Ips typographus L in pheromone traps barriers and in single traps were tested. Pheromone dispensers with different percentages of (4S)‐cis‐verbenol (cV) in pheromone mixtures were used. The results show that the different male catching efficiencies of pheromone trap barriers and single traps were related to the different percentages of cV in the pheromone bait. The proportions of males were higher in pheromone trap barriers than in single traps. Thus increasing the catch of males in pheromone trap barriers is possible by using a combination of pheromone traps containing pheromones giving a higher release of cV with others containing pheromones giving a lower release of cV.
Impact of mating on Anagyrus kamali Moursi (Hym., Encyrtidae) lifetime fecundity, reproductive longevity, progeny emergence and sex ratio
Authors: Sagarra L. A. , Vincent C. , Stewart R. K.
Published: March 2003

Abstract: The solitary endoparasitoid Anagyrus kamali Moursi (Hym., Encyrtidae) and the Hibiscus mealybug Maconellicoccus hirsutus Green (Hom., Pseudococcidae), were used as a parasite/host model to test the effect of mating on several fitness parameters, i.e. longevity, lifetime fecundity, progeny emergence and sex ratio. At 27 ± 2°C, 8 h light : 16 h dark, mating significantly affected the survival of male parasitoids. Virgin males lived longer (32.2 ± 9.51 days) than mated males (23.9 ± 7.52 days). Female longevity (40.7 ± 16.3 days for virgins and 36.2 ± 10.7 days for mated females) was not affected by mating. The lifetime fecundity of female parasitoids and their oviposition period was not significantly affected by mating. However, the number of hosts parasitized was greater for mated wasps (7.54 ± 4.85 hosts parasitized/day) compared with virgin ones (5.12 ± 2.19 hosts parasitized/day). This resulted in greater progeny production from mated A. kamali females. The progeny of virgin females consisted only of males, whereas the mated ones had a more female‐biased sex ratio. The lowest sex ratio (0.41 M/F ± 0.123) was attained when females had free access to males and were multi‐mated.
Role of Nosema bombycis infected male silk moths in the venereal transmission of pebrine disease in Bombyx mori (Lep., Bombycidae)
Authors: Patil C. S. , Jyothi N. B. , Dass C. M. S.
Published: March 2003

Abstract: The role of male moths of silkworm in the spread of pebrine spores (disease) has been studied using appropriate crossings and examining the multiplication of spores in the testis. Sections of infected testis reveal the presence of spores in the peritoneal sheath, spermatids but not in the sperm. A large number of spores was observed in the bursa copulatrix of the uninfected female moth mated with an infected male moth. This is a first record of venereal transmission of pebrine spores in silkworms. Venereally transmitted spores do not contribute to transovarial transmission, but give a false positive indication during mother‐moth examination. An alternative method for mother‐moth testing has also been discussed.
Impact of cypermethrin on the functional response, predatory and mating behaviour of a non‐target potential biological control agent Acanthaspis pedestris (Stål) (Het., Reduviidae)
Authors: Claver M. A. , Ravichandran B. , Khan M. M. , Ambrose D. P.
Published: March 2003

Abstract:  The impact of the insecticide cypermethrin on the functional response, predatory behaviour and mating behaviour was studied in a non‐target potential reduviid biological control agent Acanthaspis pedestris (Stål). The intensity of abnormal behaviour increased as the concentration of cypermethrin was increased. The insecticide negatively affected the functional response events such as attack ratio, handling time and rate of discovery. Cypermethrin also reduced the predatory efficiency and prolonged the mating events in A. pedestris. The type II (decelerating curve) of functional response was altered into a type IV (dome‐shaped curve) by cypermethrin.
Epidemiology of Stenocarpella macrospora (Earle) Sutton on Maize in the Mid‐altitude Zone of Nigeria
Authors: Olatinwo R. O. , Cardwell K. F. , Deadman M. L. , Julian A. M.
Published: March 2003

Disease progress of Stenocarpella macrospora (Earle) Sutton (syn. Diplodia macrospora Earle) was monitored on selected maize breeding lines over two seasons at three locations. Tagged plants were assessed at 10 day intervals for foliar lesions on a 1–9 scale and for ear rot on a 1–5 scale. The level of disease at a farm in Jos (West Africa Milk Company farm) was significantly greater than those at the other two locations (UTC Tenti and Saminaka), which had reduced or zero debris from the previous year’s cultivation. There was a significant correlation between the leaf severity score and grain weight, where grain weight decreased with increasing leaf disease severity. However, no significant correlation was observed between ear rot and leaf severity. Varieties responded differently throughout the monitoring period. Late planting (1996) resulted in a significantly reduced disease incidence, but also resulted in lower grain weights. Spatial disease progress diagrams indicated that S. macrospora was initiated from random foci from which secondary spread occurred.
Effect of Temperature During Conidial Formation of Monilinia laxa on Conidial Size, Germination and Infection of Stored Nectarines
Authors: Tian S. P. , Bertolini P.
Published: March 2003

Conidia of Monilinia laxa produced at different temperatures were studied for size and germinability, and for their pathogenicity to nectarine fruits kept in refrigerated storage at 0°C. The mycelial growth, which was evaluated on peach‐agar at temperatures ranging from 25 to −4°C, decreased with temperature and ceased at −4°C. When the temperature was lowered from 25 to 0°C, the conidia volumes increased by 41% on peach‐agar and by 15.5% on nectarines. The conidia germinated at the temperatures tested from 20 to −4°C. At germination temperature from 10 to −4°C, larger conidia produced at 0 and 5°C germinated earlier with longer germ tubes than those produced at 25°C. But when incubated at 20°C the conidia produced at 0°C germinated later or at the same time as those produced at 25°C and formed shorter germ‐tubes. Conidia produced at the lower temperatures (0 and 5°C) and inoculated onto wounded nectarines stored at 0°C, were highly infective and infectivity decreased when the conidia were produced at 25°C. The differences were particularly evident at the lower conidium suspension concentration (5 × 102 and 2 × 103 conidia ml−1). After 4 weeks 30–50% of the nectarines had rotten when the inoculation was carried out with spores at the concentrations of 5 × 102 and 2 × 103 conidia ml−1 and produced at 0°C, while the fruits infected with spores produced at 25°C were all still sound.
Superoxide Generation in Chemically Activated Resistance of Barley in Response to Inoculation with the Powdery Mildew Fungus
Authors: Kogel K.‐H. , Hückelhoven R.
Published: March 2003

In a previous work, a phenotype‐specific accumulation of superoxide radical anions (O•−2) after attack of the powdery mildew fungus (Blumeria [syn. Erysiphe] graminis f.sp. hordei) in near‐isogenic barley (Hordeum vulgare L.) lines bearing different Mlx genes for resistance was described (Hückelhoven and Kogel, 1998). We have now a histochemical study of the pathogenesis‐related O•−2 generation in the systemic activated resistance (SAR) response induced in barley cv Pallas by the plant activator 2,6‐dichloroisonicotinic acid (DCINA).

SAR‐specific defence was conducted prevalently characterized by penetration resistance. Fungal arrest was observed before haustorium formation by a highly localized cell wall reinforcement (effective papillae) and, in most cases, by a subsequent hypersensitive cell death (HR). No O•−2 generation was found in association with these plant defence responses. However, a strong O•−2 burst in the attacked epidermal cells was detected in the control plants which were not activated by DCINA. This burst coincided with cell wall penetration and subsequent contact of the pathogen with the host plasma membrane.

A strong SAR‐related O•−2 burst was induced in the mesophyll tissue beneath the attacked and hypersensitively reacting epidermal cells in plants treated with DCINA. The accumulation of O•−2 was confined to chloroplasts. The remarkable burst in mesophyll tissue was not followed by mesophyll‐HR indicating that chloroplastic O•−2 generation is not sufficient for the hypersensitive cell death. Since the same pattern of pathogenesis‐related O•−2 accumulation was identified for race‐specific response mediated by the Mlg gene for powdery mildew resistance, the present data are consistent with the hypothesis that the SAR phenotype is a phenocopy of the Mlg‐type resistance (Kogel et al., 1994).
Differentiation of Poaceae Potyviruses by Reverse Transcription‐Polymerase Chain Reaction and Restriction Analysis
Authors: Marie‐Jeanne V. , Ioos R. , Peyre J. , Alliot B. , Signoret P.
Published: March 2003

Four potyviruses have been reported to infect Poaceae: maize dwarf mosaic virus (MDMV), sugarcane mosaic virus (SCMV), johnsongrass mosaic virus (JGMV) and sorghum mosaic virus (SrMV). A procedure was developed to assess the potential presence of potyviruses in a Poaceae‐infected sample, and then to determine which potyvirus species (one or more) were present. The first step was potyvirus‐group specific and following total RNA extraction, reverse transcription and polymerase chain reaction, it yielded a 327 nucleotide fragment spanning MVWCIEN to QMKAAA conserved motifs in the core of the capside gene. Enzymatic restriction of this fragment with the two endonucleases AluI and DdeI gave virus‐specific patterns. This method was shown to be efficient for dealing with well‐characterized strains and field collected isolates and useful for determining co‐infections and detecting a new potyvirus infecting maize.
Antifungal Activity of a Bowman–Birk‐type Trypsin Inhibitor from Wheat Kernel
Authors: Chilosi G. , Caruso C. , Caporale C. , Leonardi L. , Bertini L. , Buzi A. , Nobile M. , Magro P. , Buonocore V.
Published: March 2003

A trypsin inhibitor from wheat kernel (WTI) was found to have a strong antifungal activity against a number of pathogenic fungi and to inhibit fungal trypsin‐like activity. WTI inhibited in vitro spore germination and hyphal growth of pathogens, with protein concentration required for 50% growth inhibition (IC50) values ranging from 111.7 to above 500 μg/ml. As observed by electron microscopy, WTI determined morphological alterations represented by hyphal growth inhibition and branching. One of the fungal species tested, Botrytis cinerea produced a trypsin‐like protease, which was inhibited by the trypsin inhibitor. WTI, as well as other seed defence proteins, appear to be an important resistance factor in wheat kernels during rest and early germination when plants are particularly exposed to attack by potential soil‐borne pathogens.
Differential Behaviour of Mycelial Growth of Several Botrytis cinerea Strains on either Patchoulol‐ or Globulol‐amended Media
Authors: Vallejo I. , Rebordinos L. , Collado I. G. , Cantoral Fernández J. M.
Published: March 2003

Botrydial and dihidrobotrydial are two characteristic metabolites of the phytopathogenic fungus Botrytis cinerea, which are involved in the development of necrotic lesions on grapevine and tobacco. Patchoulol and globulol, two natural products which are analogues to precursors of botrydial and dihidrobotrydial, were tested on 10 B. cinerea strains which were isolated from different hosts and varied in aggressiveness on grapevine leaves. Mycelial growth of all strains was prevented when they were grown on either patchoulol‐ or globulol‐amended malt agar media (200 μg/μl). Each strain displayed a specific response pattern to those products, according to the high variability previously described for this species. Furthermore, strains were different from one another with regard to their level of aggressiveness against leaves detached from sherry grapevine vineyards.
Use of Rhizobacteria in the Control of Root Rot–Root Knot Disease Complex of Mungbean
Authors: Ali Siddiqui I. , Ehetshamul‐Haque S. , Shahid Shaukat S.
Published: March 2003

Thirty‐two isolates of Pseudomonas aeruginosa and a Bacillus subtilis strain were isolated from rhizosphere and rhizoplane of four wild and 15 cultivated plants. Biocontrol and growth‐promoting potentials of the bacterial isolates were tested under laboratory, greenhouse and field conditions. The bacterial isolates not only exhibited nematicidal activity by killing the second stage larvae of Meloidogyne javanica to a varying degree but also produced inhibition zones by inhibiting the radial growth of Macrophomina phaseolina, Fusarium solani and Rhizoctonia solani. Strain IE‐2 and IE‐6 of P. aeruginosa also lysed the fungal mycelium. P. aeruginosa and B. subtilis used as seed dressing or as soil drench significantly suppressed root rot–root knot infection and nematode population densities under greenhouse and field conditions and thereby enhanced plant growth and yield in mungbean.
The Response of Cochliobolus sativus to Ultraviolet‐C Radiation
Authors: Arabi M. I. E. , Jawhar M.
Published: March 2003

Isolates of Cochliobolus sativus, the cause of common root rot of barley, were collected from different regions of Syria, and exposed in the laboratory to ultraviolet‐C (UV‐C) light (254 nm) during periods of 40 or 60 h with a dose rate of 2.52 × 10–3 W/cm2. Significant increases (P < 0.001) in mycelial growth and sporulation were detected in comparison with the non‐ irradiated control, and these increased with increasing exposure to UV‐C. This exposure increased the mycelial growth by 89 and 100% in the isolates CR9 and CR19, respectively, and the number of spores by 10‐ and 13‐fold, respectively. Some of the isolates retained and some increased in virulence. These data demonstrate that variation occurred in the virulence level and the resistance level of isolates and among accessions, respectively.
Relative Resistance of Four Peach Rootstocks to Phytophthora cactorum and Phytophthora megasperma
Authors: Thomidis T. , Cullum J. , Elena K. , Jeffers S. N.
Published: March 2003

Shoot samples of four peach rootstocks that are important to the peach industry in Greece: KID I, GF305, GF677, and PR204, were inoculated with Phytophthora cactorum and Phytophthora megasperma in the field and in the glasshouse and were then evaluated with regard to susceptibility. The pathogenicity of P. cactorum and P. megasperma to peach rootstocks was confirmed with an excised twig assay. The peach rootstocks showed differential susceptibility to P. cactorum. GF305 was the least susceptible and KID I was the most susceptible, which suggests that the latter rootstock is unsuitable for orchards in which the conditions are favourable for Phytophthora diseases. GF677 and PR204 were moderately susceptible. The plants that were inoculated with P. megasperma in the field and in the glasshouse showed no sign of infection whereas twigs inoculated in vitro with P. megasperma developed necrosis. GF305 was the most resistant, KID I was the most susceptible and PR204 and GF677 were moderately resistant. The present results demonstrate that none of the four peach rootstocks used in this study was completely resistant to P. cactorum, particularly when rootstocks were flooded periodically to enhance disease development. Therefore an integrated approach including host and resistance cultural practices is recommended to manage diseases caused by P. cactorum in peach orchards in Greece.
The Effects of Temperature on the Incubation and Latent Periods of Powdery Mildew (Erysiphe polygoni) on Clematis
Authors: Xu X. , Robinson J.
Published: March 2003

The effects of temperature on the length of the incubation and latent periods of clematis powdery mildew, caused byErysiphe polygoni, were studied. At constant temperatures over the range of 10–29°C, the length of the incubation period ranged from 4 to 11 days, and the length of the latent period ranged from 4 to 13 days; no visible colonies developed at 30°C after 19 days. The relationship between temperature and the rates of fungal development within the incubation and latent periods (expressed as the reciprocal of the lengths of the incubation and latent periods) under constant temperature were described well by a non‐linear model. The resulting curves were not the usual form of an asymmetrically bell‐shaped type; instead, they were of exponential type with the development rate increasing with increasing temperatures. The relationship between temperature and the development rate during the post‐incubation (before sporulation) period was non‐linear with an optimum temperature of approximately 20°C.
In Vitro Effects of Film‐Forming Polymers on the Growth and Morphology of Pyrenophora Avenae and Pyricularia Oryzae
Authors: Sutherland F. , Walters D. R.
Published: March 2003

Ethokem (Midkem Agrochemicals, Northampton, UK) and Bond (Newman Agrochemicals, Cambridge, UK) completely inhibited linear growth of Pyricularia oryzae at 1 and 2% concentrations of the compounds and strongly inhibited growth of Pyrenophora avenae in vitro. Vapor Gard (Miller Chemical & Fertilizer Corporation, Hannover, PA, USA) was less effective with relatively little inhibition of P. oryzae, but was a more effective inhibitor of P. avenae. All three compounds decreased cell lengths of both pathogens and increased cell diameters of P. avenae. Vapor Gard and Ethokem did not significantly alter cell diameters of P. oryzae, but a highly significant increase was observed with Bond. Gross changes in hyphal morphology were observed including swollen shortened cells, granulation of the cytoplasm, increased branching and collapsed empty cells. Ethokem and Bond decreased growth rate and inhibited biomass production of P. avenae.
Molecular Genetic Diversity and Variation for Aggressiveness in Populations of Fusarium graminearum and Fusarium culmorum Sampled from Wheat Fields in Different Countries
Authors: Miedaner T. , Schilling A. G. , Geiger H. H.
Published: March 2003

Fusarium graminearum and Fusarium culmorum are the major pathogenic organisms causing head blight in small‐grain cereals. Natural epidemics may result in severe yield losses, reduction in quality, and contamination of the grain by mycotoxins. The genetic diversity of four field populations of F. graminearum from Germany, Hungary, and Canada, and one population of F. culmorum from Russia was investigated by polymerase chain reaction (PCR)‐based fingerprinting. Additionally, a world‐wide collection and two of the F. graminearum populations were analysed for their aggressiveness on young plants of winter rye in the greenhouse. The number of isolates analysed per population varied from 25 to 70. Significant quantitative variation for aggressiveness was observed within each of the individual field populations amounting to the same range as the world‐wide collection. Abundant variation within populations was also revealed by DNA markers. The F. graminearum populations from Hungary and Winnipeg displayed the least genotypic diversity, the two German F. graminearum populations and the Russian F. culmorum population were highly diverse. Population diversity, however, followed no spatial pattern among samples within a German field for aggressiveness or molecular markers. For F. graminearum, sexual recombination is the most likely explanation for the large genetic diversity within field populations. Asexual and/or parasexual recombination, and balancing selection caused by the periodic alternation between the saprophytic and parasitic phase might play an additional role and account for the variation within the F. culmorum population. For improving Fusarium resistance, several resistance genes of different sources should be combined to avoid an unspecific adaptation of the genetically variable pathogen to an increased resistance level.
Effect of Temperature on the Formation of Microsclerotia of Verticillium dahliae
Authors: Soesanto L. , Termorshuizen A. J.
Published: March 2003

Microsclerotium formation by six isolates of Verticillium dahliae was studied at different temperatures both in vitro and in Arabidopsis thaliana. In vitro mycelial growth was optimal at 25°C, but microsclerotium formation was greatest at 20°C (two isolates) or 15–20°C (one isolate). Seedlings of A. thaliana were root‐dipped in a conidial suspension, planted, and either placed at 5, 10, 15, or 25°C, or left at 20°C until the onset of senescence, after which some of the plants were placed at 5, 10, 15, or 25°C. The amount of microsclerotia per unit of shoot weight was assessed in relation to isolate and temperature. The optimal temperature for production of microsclerotia was 15–25°C. Two isolates each produced about 10 times more microsclerotia than each of the other four isolates. For these isolates, high R2adj.‐values of 0.77 and 0.66 were obtained, with temperature and its square as highly significant (P < 0.001) independent variables. R2adj.‐values for the other isolates varied between 0.28 and 0.39. Moving plants to different temperatures at the onset of senescence led to microsclerotial densities that were intermediate between densities on plants that had grown at constantly 20°C and plants grown at other temperatures. This suggests that vascular colonization rate and rate of microsclerotium formation are similarly affected by temperature. The senescence rate of plants appeared unimportant except for plants grown at 25°C, which showed the highest amounts of microsclerotia per unit of plant weight in the most rapidly senescing plants.
Interaction Effects of Citrus Rootstocks, Salinity and Tylenchulus semipenetrans Parasitism on Osmotically Active Ions
Authors: MASHELA P. W. , NTHANGENI M. E.
Published: March 2003

High densities of Tylenchulus semipenetrans and slow decline symptoms are dominant in citrus‐producing areas with high salinity. Currently, no commercial citrus rootstock is both nematode‐resistant and salt‐tolerant. Interaction effects of citrus rootstocks, salinity and T. semipenetrans were evaluated for the partitioning of salinity ions (Cl and Na) and K in microplots. Treatments comprised six citrus rootstocks with wide ranges of salt tolerance, 0 and 3 mols NaCl + 0.25 mols CaCl2 l−1 water and 0 and 856 300 nematodes. At harvest, eight months after salinity treatments, the three–factor interaction was significant (P=0.05) for the alteration in the partitioning of salinity ions and K. Nematodes generally increased salinity ions in leaves and reduced salinity ions in roots and K in both leaves and roots. Thus, management of nematodes is critical in areas with salinity problems.
Changes in Wheat Leaf Extracellular Proteolytic Activity after Infection with Septoria tritici
Authors: SEGGARRA C. I. , CASALONGUÉ C. A. , PINEDO M. L. , CORDO C. A. , CONDE R. D.
Published: March 2003

The proteolytic activity of the leaf extracellular space of wheat cultivars Pigüé and Isla Verde was estimated after inoculation of either detached leaves or plants with the fungus Septoria tritici. Pigüé is resistant, whereas Isla Verde is susceptible to the disease caused by S. tritici. Viable conidiospores of the fungus caused similar increases in both hydrogen peroxide production and chitinase activity of the cultivars studied. In contrast, they caused a decrease in the extracellular serine proteinase activity of Isla Verde and a significant increase in that of Pigüé. Independently of the cultivar from which it was extracted, the extracellular serine proteinase inhibited the germination of Septoria tritici conidiospores. These results suggest that the proteolytic activity of the leaf extracellular space can participate in the defence of wheat plants against Septoria tritici. Its regulation may be controlled by specific defence components of each cultivar.
The First Record and Characterization of Powdery Mildew (Erysiphe pachypodiae sp. nov.) on Pachypodium lamerei (Apocynaceae)
Authors: LEBEDA A. , MIESLEROVÁ B. , DOLEZ˘ALOVÁ I.
Published: March 2003

During the summer and autumn of 1999, symptoms of powdery mildew disease were first observed on Pachypodium lamerei in the Czech Republic. White lesions of irregular shape appeared on leaf margins and spread towards the central vein of the leaf, often followed by necrosis of leaf tissue. In the spring of 2000, the sexual stage (cleistothecia) also appeared on infected leaves. Based on the observations of the morphology of its anamorph and teleomorph stage as well as on results from inoculation experiments, the identity and origin of this powdery mildew species are discussed. Based on the pseudoidium anamorph, this fungus may be clearly assigned to Erysiphe emendation, probably to section Uncinula, since the cleistothecial appendages are non‐mycelioid and occassionally circinate at the apex. The fungus is described as a new species Erysiphe pachypodiae sp. nov.
Studies on Symptom Development, Phenolic Compounds and Morphological Defence Responses in Wheat Cultivars Differing in Resistance to Fusarium Head Blight
Authors: SIRANIDOU E. , KANG Z. , BUCHENAUER H.
Published: March 2003

Abstracts

Development of Fusarium head blight, caused by Fusarium culmorum, was evaluated in seven winter wheat cultivars and one spring wheat cultivar in an outdoor pot experiment. Of the cultivars studied, only the spring wheat cultivar Frontana exhibited resistance against initial infection by the fungus. Significantly higher amounts of free phenolic compounds were found in the glumes, lemmas and paleas of Frontana prior to and at all sampling times after inoculation, in comparison to the winter wheat cultivar Agent. Furthermore, the amount of p‐coumaric acid increased significantly in the glumes, lemmas and paleas of the cultivar Frontana 2 days after inoculation compared to that in uninoculated spike tissues. However, the amounts of ferulic acid between inoculated and healthy plant tissues did not differ. Ultrastructural studies indicated more pronounced structural defence responses, such as cell wall appositions, in the infected lemma tissue of the resistant cultivar Frontana compared with the susceptible Agent 3 days after inoculation. Immunogold labelling of lignin revealed no differences in the density of gold particles on the cell walls of healthy lemma tissue in the two cultivars. However, density of particles increased in the infected lemma tissue of the resistant cultivar Frontana on cell walls adjacent to the fungal cells, 3 days after inoculation. The susceptible cultivar Agent showed little or no response to the infection. Phenolic compounds appear to play a role in the resistance of the cultivar Frontana to F. culmorum.
Potential of Trichoderma harzianum and T. atroviride to Control Botryosphaeria berengeriana f. sp. piricola, the Cause of Apple Ring Rot
Authors: KEXIANG G. , XIAOGUANG L. , YONGHONG L. , TIANBO Z. , SHULIANG W.
Published: March 2003

Trichoderma harzianum T88 and T. atroviride T95 were tested for their efficacy in controlling apple ring rot (caused by Botryosphaeria berengeriana f. sp. piricola) in vitro and in the field. Isolates of T88 and T95 produced both volatile and non‐volatile antibiotics that suppressed mycelial growth of the pathogen. Light and scanning electron microscopy showed that mycoparasitism by Trichoderma spp. of B. berengeriana f. sp. piricola resulted in penetration and disruption of hyphal cells, and thinning of cytoplasm of the pathogen. The culture filtrates of T88 and T95 in Czapek's liquid medium suppressed conidial germination of the pathogen, and the germination level was negatively correlated with the duration of culture of Trichoderma. In inoculation tests, 32 days after simultaneous inoculation or preinoculation with B. berengeriana f. sp. piricola and Trichoderma spp., the incidence of infected apple shoots was reduced, respectively, by 65.3–76.4% and 62.5–76.4%, and the index of infection reduced by 36.9–38.9 and 40.7–44.4, The effect of inoculating B. berengeriana f. sp. piricola 3 days after the antagonists were inoculated was greater (81.4–88.8%) than simultaneous inoculation (72.2–77.8%). Re‐isolation from inoculated apple shoots demonstrated that the pathogen had been suppressed by Trichoderma. The ability to re‐isolate the pathogen from apple after co‐inoculation and pre‐inoculation with Trichoderma spp. was reduced by 27.0–42.3% and 22.2–47.1%, respectively. The biocontrol field trial suggested that the B. berengeriana f. sp. piricola canker on apple shoots and stems and rotting fruit had been efficiently controlled by the application of spore suspensions of T. harzianum T88 and T. atroviride T95. The efficacy of control by Trichoderma is thus similar to that of routine chemical control.
Anastomosis Group Determination of Rhizoctonia solani Kühn (Telemorph: Thanatephorus cucumeris) Isolates from Tomatoes Grown in Aydin, Turkey and their Disease Reaction on Various Tomato Cultivars
Authors: Yildiz A. , Döken M. Timur
Published: March 2003

In the Province of Aydin‐Turkey most frequently Fusarium spp. and secondly Rhizoctonia solani Kühn were isolated from the roots and crown of tomato plants. Based on affinities for hyphal fusion with test isolates, all R. solani isolates were identified as AG‐4. The tomato cultivars which were grown in soil infested with R. solani AG‐4 exhibited different reactions. From the point of symptom expression and the rate of seedling emergence Sunny 6066 F1 was found to be the most resistant cultivar, whereas Rio Grande, Rio Fuego, NDM 725, Interpeel and Konia were the most susceptible cultivars.
CAPS and DHPLC Analysis of a Single Nucleotide Polymorphism in the Cytochrome b Gene Conferring Resistance to Strobilurins in Field Isolates of Blumeria graminis f. sp. hordei
Authors: Bäumler S. , Felsenstein F. G. , Schwarz G.
Published: March 2003

A single nucleotide polymorphism in the wheat powdery mildew (Blumeria graminis f. sp. tritici) cytochrome b gene is responsible for resistance to inhibitors of the quinol outer binding site of the cytochrome bc1 complex (QoI) fungicides. Analysis of a partial sequence of the cytochrome b gene from field isolates resistant and sensitive to QoI fungicides revealed the same point mutation in barley powdery mildew (B. graminis f. sp. hordei). Analysis of 118 and 40 barley powdery mildew isolates using a cleaved amplified polymorphic sequence assay and denaturing high performance liquid chromatography, respectively, confirmed that this single nucleotide polymorphism also confers resistance to QoI fungicides in barley powdery mildew.
Department of Clinical Studies, The Royal Veterinary and Agricultural University, Copenhagen, Denmark
Authors: Hagedorn‐Olsen T. , Nielsen N. C. , Friis N. F. , Nielsen J.
Published: March 2003

In this investigation, natural infection with Mycoplasma hyosynoviae was followed in groups of individual pigs in three different herds with regard to occurrence of tonsillar carrier state, clinical arthritis and development of antibodies in serum and in synovial fluid. Antibodies were detected by a polyclonal enzyme‐linked immunosorbent assay (ELISA) developed for experimental use. The infection with M. hyosynoviae progressed very differently in the three herds investigated. In one herd, the infection was apparently limited to adult pigs. In a second herd, all pigs became tonsillar carriers of M. hyosynoviae, but no mycoplasma‐related arthritis nor any serological response was demonstrated within the growing–finishing period. In the third herd investigated, tonsillar infection was detected in all pigs, clinical cases of M. hyosynoviae arthritis followed and a moderate serological response was observed in some, but not all, pigs. In all three herds, M. hyosynoviae infection was carried in the tonsils of the adult pigs, but it was only occasionally transmitted from sows to piglets. Maternal antibodies were transferred to the piglets and persisted for approximately 8–12 weeks. After weaning, some pigs became infected before 20 weeks of age, while others did not. In the majority of cases, the tonsillar infection was established from 11 weeks of age or older. A latent tonsillar infection was present for a period of several weeks within the group of investigated pigs before cases of generalized infection and arthritis were seen. In some cases, generalization of M. hyosynoviae infection in the blood and in joints was observed in spite of the detection of an active serological response a few weeks earlier. The present work suggests that generalization of the infection and development of arthritis may depend on age, immunity, virulence factors and/or infection pressure; in some herds maybe combined with certain triggering mechanisms such as stress and lowered general resistance.