bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of dietary β‐carotene on the early embryonic development and uterine fluid composition of gilts
Authors: Schweigert F. J. , Krieger K. , Schnurrbusch U. , Schams D. , Gropp J.
Published: March 2003

The role of β‐carotene in reproduction was investigated in gilts assigned to three dietary supplementations: VA (4000 IU vitamin A); VA + VA (4000 IU + 8300 IU); VA + BC (4000 IU + 100 mg β‐carotene) per kg diet for 14 weeks. Gilts were slaughtered at day 12 of gestation. In the VA + BC group, number of corpora lutea was lowest, but the number of embryos was greatest, resulting in a non‐significant decreased prenatal mortality(p<0.07). The proportion of less developed spherical and tubular embryos compared with filamentous was greatest in the VA + BC group (p<0.01). No differences were observed for vitamin A and retinal binding protein (RBP) in the uterine fluid. When animals were grouped according to the development of blastocysts, vitamin A and RBP levels were higher in the VA + BC group with only filamentous embryos (p<0.01). This indicates that the supplementation of β‐carotene to gilts might affect embryonic losses possibly because of slower alterations in the uterine environment, resulting in a higher and less variable number of embryos, despite an apparently more heterogeneous development.
Effect of Artemisia annua oil on development and reproduction of Dysdercus koenigii F. (Hem., Pyrrhocoridae)
Authors: Rao P. J. , Kumar K. Mahesh , Singh S. , Subrahmanyam B.
Published: March 2003

The effect of topical application of Artemisia annua oil on the development and reproduction of Dysdercus koenigii was studied. On the basis of 48 h mortality, the LD50 for fifth instar nymphs was 0.48 μl/nymph. The treated nymphs showed 2 days delay in development, and also produced intermediates. The treatment decreased haemolymph protein concentration and disturbed its electrophoretic protein pattern. The adults which emerged from treated nymphs showed poor ovary development. There was a greater median neurosecretory activity in the treated insects compared with control insects till day 6 of adult life.
Biology and distribution of microbe‐associated thelytokous populations of aphid parasitoids (Hym., Braconidae, Aphidiinae)
Authors: Starý P.
Published: March 2003

Abstract: Some phenomena of the biology and ecology of the microbe (Wolbachia)‐associated thelytokous populations of aphid parasitoids are presented for the first time. Thelytokous virgin females were found to refuse the mating attempts by males of biparental populations, although males occurred quite rarely among the offspring. The host range was found to be about identical in conspecific biparental and thelytokous populations, whereas the association of solely biparental populations with a certain host group might be considered as a marker of the presence of sibling species in the area. The relative frequency of conspecific biparental and thelytokous populations varied, depending upon the area and host species. The microbe‐induced thelytokous populations were confirmed in three species of the genus Lysiphlebus Foerst. (Lysiphlebus cardui Marsh., Lysiphlebus confusus Tremblay and Eady, Lysiphlebus fabarum Marsh.) and probably some other, as yet undescribed, species only in the West Palearctic subregion, whereas the other known congeneric species in the subregion as well as in the Nearctic and the Neotropical regions were determined as strictly biparental species. Microbe‐induced thelytokous populations did not change due to host species alternation and/or distribution area (purposeful introductions as biocontrol agents).
Impacts of Tomicus minor on distribution and reproduction of Tomicus piniperda (Col., Scolytidae) on the trunk of the living Pinus yunnanensis trees
Authors: Hui Y. , Xue‐Song D.
Published: March 2003

This study investigated the impacts of Tomicus minor on Tomicus piniperda when the two Tomicus species coexist in the trunks of living Yunnan pine (Pinus yunnanensis L.) trees growing in the Kunming region, in south‐western China. Tomicus piniperda mostly locates in the mid‐ and upper trunks of Yunnan pine tree; whereas T. minor mainly attacks the mid‐ and lower trunks. In the mid‐trunk area from 1.0 to 5.0 m above ground, there are overlapping attack zones for the two Tomicus species, which accounts for an average of 80% of the entire zone occupied by T. piniperda and an average of 70% of the zone occupied by T. minor. In correspondence with their attack distributions, the average attack densities of the two species varied with height along the trunk, with 165.3 egg galleries per m2 at a height of 6 m for T. piniperda, and 138.2 egg galleries per m2 at the 1 m height for T. minor. It is suggested that T. minor adjusts its attack pattern with respect to T. piniperda, and thereby minimizes interspecific competition. No remarkable difference of average T. piniperda egg gallery length was found between the zone in which only T. piniperda occurred and the zone in which T. piniperda and T. minor coexisted; this is suggested to be due to low host quality in the upper trunk region where only T. piniperda was present. The number of T. piniperda larval galleries was highest when only T. piniperda was present, and decreased as T. piniperda and T. minor coexisted, particularly in the case when the density of T. piniperda was less than that of T. minor. Average larval density was 1649 larval galleries per m2 where only T. piniperda occurred. However, when T. piniperda coexisted with T. minor, T. piniperda larval density averaged 1010 per m2 when T. piniperda density was higher than T. minor, and averaged 442 per m2 when T. piniperda density was less than T. minor, which led to the conclusion that T. minor makes a negative impact on T. piniperda reproduction when the two Tomicus species jointly colonize the same trunk of Yunnan pine tree.
Suitability of physic nut (Jatropha curcas L.) as single host plant for the leaf‐footed bug Leptoglossus zonatus Dallas (Het., Coreidae)
Authors: Grimm C. , Somarriba A.
Published: March 2003

The leaf‐footed bug Leptoglossus zonatus (Dallas) (Het., Coreidae) was reared in Nicaragua on a diet consisting of unripe physic nut (Jatropha curcas L., Euphorbiaceae) fruit only. The suitability of this host plant is described by the mortalities in the developmental stages from egg to adult, which are presented in a life table, and the durations of the different stages. Pre‐oviposition time, number of ovipositions and total number of eggs per female are given. Biometric measurements of all instars were made. Protein, oil and water content of fresh physic nut fruit were measured throughout a whole year. The results show that physic nut is a highly suitable host plant, which can maintain populations of this insect pest throughout the whole year as fruit are constantly present with only little fluctuation in their nutritional quality.
Structure of egg‐batches of Thaumetopoea pityocampa (Den. and Schiff.) (Lep., Thaumetopoeidae), egg parasitoids and rate of egg parasitism on the Iberian Peninsula
Authors: Schmidt G. H. , Tanzen E. , Bellin S.
Published: March 2003

In four regions of the Iberian Peninsula 273 egg‐batches of the pine processionary moth were collected after hatching of the caterpillars in 1991 and 1992. After collection, the batches were stored singly in test tubes closed with foam stoppers under laboratory conditions at 20–25°C. The number of eggs in each egg‐batch varied between 37 and 312 and the length of the batches between 0.6 and 4.2 cm. Independently of the pine species infested, seven to nine rows of eggs were counted, wrapped around one pair of needles. A correlation was found between number of eggs and the product of number of egg rows and length of egg‐batches (82% < r2 < 97%). Oviposition almost always started from the base towards the tip of the needles. The egg parasitoids that emerged were counted daily, removed and identified. Later in the year of oviposition, after the end of the period of emergence of the parasitoids, the scale cover of the egg‐batches were removed. One year later, all eggs were opened and the contents, such as parasitoid meconia and remains of caterpillars, were determined. The hatching rate of the caterpillars varied from 47.2 to 79.7%. The rate of parasitism fluctuated between 11.3 and 31.7%, but 44% of parasitoids died before successful emergence. Four species of Chalcidoidea were identified: Baryscapus servadeii (Dom.), Ooencyrtus pityocampae (Mercet), Anastatus bifasciatus (Fonsc.) and Trichogramma sp. Baryscapus servadeii and O. pityocampae were the most abundant species, followed by Trichogramma sp. Baryscapus servadeii emerged mainly in June and O. pityocampae in April or June, depending on the region. For A. bifasciatus only males, and for B. servadeii females emerged except one male. In O. pityocampae, a relatively high percentage of males (5.4–10.4%) was found.
Qualitative aspects of myrmecocenosis (Hym., Formicidae) in olive orchards with different agricultural management in Spain
Authors: Redolfi I. , Tinaut A. , Pascual F. , Campos M.
Published: March 2003

A study has been made of the presence of ants in 60 olive trees in each of three orchards under different agricultural management in the province of Granada (southern Spain), during the months of May, July and September 1997, using both observational methods as well as the collection of specimens from the soil and trunk and the tree canopy. A total of 18 species of ants were identified, 16 of which were present in the orchard of Arenales, four in Colomera 1, and nine in Colomera 2. The number of species varies over the survey, being greatest before the flowering of the trees, this period coinciding with the lowest temperatures. The species Tapinoma nigerrimum (Nylander) was the only species present in all the samplings of the olive orchards, and the other common species in the three zones proved to be: Messor barbarus (L. 1767), Tetramorium semilaeve André and Plagiolepis pygmaea (Latr.). Most of the species found made their nests in the soil under the tree canopy, and only four species nested exclusively in open areas. Ten species foraged in the tree and seven foraged in groups. The three olive orchards were similar in phenology, temperature and humidity, and therefore the differences in the myrmecofauna at the different sites were attributed to agricultural practices at each site.
Assessment of site characteristics as predictors of the vulnerability of Norway spruce (Picea abies Karst.) stands to attack by Ips typographus L. (Col., Scolytidae)
Authors: Dutilleul P. , Nef L. , Frigon D.
Published: March 2003

The intensity of bark beetle Ips typographus L. (Col., Scolytidae) attack on Norway spruce (Picea abies Karst.) is known to vary greatly among stands. In a control strategy approach, previous studies investigated the relationships between the variability in intensity of I. typographus attack and site characteristics such as stand age and altitude, mean tree circumference, growth rate and nearest‐neighbour distance, soil moisture, pH in H2O and KCl, and soil contents of C, N, K, P, Mg, Ca, Fe, Cu, Zn and Mn. The data analysis method used in these studies was mainly the multiple linear regression, with the mean number of attacks per spruce tree in a stand as variable to explain. Previous results showed that the expected vulnerability of a Norway spruce stand to attack by I. typographus can be estimated on the basis of simple information of easy access to the forester, when the data on the stand in question is used with others for fitting the regression model. Prediction of the vulnerability of a stand, without including its data in the fitting of the model, was shown to be more approximate. Therefore, the objectives of this study were: (1) to improve the performance of models predicting the vulnerability of Norway spruce stands to attack by I. typographus, based on site characteristics; (2) to assess the stability of such predictive models when these are built using a moderate number of stands; and (3) to incorporate the resulting information in a global approach to control and prevention. Published data were re‐analysed for these purposes. A jackknifed multiple linear regression procedure, in which each stand in turn is discarded when fitting the model (jackknife replication), is presented. A great variability in the models fitted, depending on the stand discarded, is observed. For instance, the number of explanatory variables retained ranges from one (i.e. soil P content, for five jackknife replications) to 10 (for one jackknife replication), for R2‐values ranging from 0.5 to 1.0 and for one influential stand (i.e. the same stand characterized by an atypically low number of insect attacks compared to other stands with similar soil P content) against many influential stands. Differences between the model finally selected here using the revisited data and the models proposed earlier are discussed. A path analysis diagram is proposed for a more comprehensive modelling of Norway spruce stand vulnerability to I. typographus attack, based on site characteristics.
Laboratory and field studies on the integrated pest management of Helicoverpa armigera (Hübner) in cotton, based on pheromone trap catch threshold level
Authors: Reddy G. V. P. , Manjunatha M.
Published: March 2003

Abstract: With a view to using parasitoids and predators in integrated pest management of the target pest Helicoverpa armigera in cotton fields, basic studies on the egg parasitism, toxicity of insecticides to parasitoids and predators and compatibility of nuclear polyhedrosis virus (NPV) of H. armigera with other insecticides were conducted in the laboratory. Results revealed that egg parasitism in the laboratory by Trichogramma chilonis was 75.6%. Among the insecticides tested against T. chilonis and the predator Chrysoperla carnea, nimbecidine (neem product) and dipel resulted in zero mortality, with only a low level of mortality by dimethoate, cypermethrin, fenvalerate, alphamethrin and monocrotophos. Combinations of nimbecidine 2% + NPV at 250 larval equivalents (LE)/ha and dipel 8 l + NPV @250 LE/ha were the most effective treatments against H. armigera. The integrated pest management components (T. chilonis, C. carnea, NPV, nimbecidine, dipel and synthetic chemicals) were imposed at different intervals on the basis of pheromone trap threshold level (7 moths/trap per night) on a consolidated block of 40 ha cotton (MCU‐1) fields at two locations, Shankarabanda and Korlagundi. The results demonstrated a significant superiority of the IPM strategy in terms of both cost versus benefit and environmental safety over that used in the farmer's fields where only conventional control methods were followed.
Cono‐ and seminiphagous insects of Norway spruce Picea abies (L.) Karst. and their parasitoids in lower and upper montane zone of the Tatra National Park in Poland
Authors: Kozioł M.
Published: March 2003

Abstract: A study of the insects inhabiting of cones of Norway spruce Picea abies (L.) Karst. in the Tatra National Park was conducted during 1987–92. As a result of breeding and analyses of the cones collected from trees at various altitudes above sea level, 53 746 specimens of cono‐ and seminiphagous insects were collected. Interior damage to cones and the losses of spruce seeds caused by pests were measured, with regard both to the variable cone crop abundance of spruce and to different altitudes above sea level. The role of parasitoids in limiting the numbers of some cono‐ and seminiphagous insects was also estimated.
Polymorphic adaptive insecticidal resistance in Rhynocoris marginatus (Fabr.) (Het., Reduviidae) a non‐target biocontrol agent
Authors: George  , Ambrose
Published: March 2003

Rhynocoris marginatus (Fabr.) is a polymorphic reduviid predator inhabitating tropical rainforests, semi‐arid zones, scrub jungles and agro‐ecosystems and predates upon insect pests. It exists in three different morphs; (1) with black connexivum (niger); (2) with red connexivum (sanguineous); and (3) with black and red banded connexivum (nigrosanguineous). Insecticides used to manage insect pests affect non‐target biocontrol agents such as R. marginatus. Hence laboratory experiments were conducted to evaluate the adaptive polymorphic resistance of the morphs of R. marginatus to the toxic effects of three insecticides, namely, dimethoate, methylparathion and quinalphos, with each in five concentrations. The 50% lethal concentration (LC50) values clearly indicated that methylparathion was the most toxic insecticide followed by quinalphos and endosulfan to all three morphs. Among the three morphs, the niger was the most resistant and the sanguineous was the most sensitive.
Temperature influences walking speed and walking activity of Trichogramma brassicae (Hym., Trichogrammatidae)
Authors: Suverkropp B. P. , Bigler F. , Van Lenteren J. C.
Published: March 2003

Walking speeds and walking activities (walking time divided by total time) of Trichogramma brassicae were determined at 12, 16, 20 and 25°C. Walking speed was measured during a 5‐min period, and walking activity over a 4‐day period. Both walking speed and walking activity were strongly influenced by temperature. Walking speed increased linearly with the temperature and was twice as high at 20 as at 12°C. At 25°C, walking activity was high during the whole day, at 20 and 16°C it decreased during the afternoon, whereas at 12°C the wasps became most active only at noon or later. At low temperatures, there was a strong individual variation in walking activity. At 25°C, T. brassicae was active most of the time, so the area searched per time unit can only increase at temperatures above 25°C if walking speed increases. At temperatures below 20°C, searching was more restricted by low walking activity than by low walking speed. Even disregarding other effects of temperature, the reduction in walking speed and walking activity at suboptimal temperatures means that T. brassicae can only search half of the area at 20°C, and only one‐seventh at 15°C that it can search at 25°C.
Life history parameters of Orius sauteri (Poppius) (Het., Anthocoridae) reared on Ephestia kuehniella eggs and the minimum amount of the diet for rearing individuals
Authors: Yano E. , Watanabe K. , Yara K.
Published: March 2003

Abstract: Mass rearing techniques are essential elements in developing a reliable and economic biological control method for Orius sauteri, a promising indigenous Orius species for biological control of Thrips palmi in greenhouses. Orius sauteri was reared on Ephestia kuehniella eggs and life history parameters and the minimum number of E. kuehniella eggs for rearing O. sauteri individuals were measured at 25°C and L16:D8. Developmental time during the nymphal stages was about 14 days for both sexes. Total fecundity and female longevity were 103.9 and 27.9 days, respectively. The intrinsic rate of natural increase per day was 0.115. An individual requires at least 30 eggs for nymphal development and survival and 20 eggs for adult oviposition and survival per four days.
Susceptibility of immature stages of Chrysoperla rufilabris (Neurop., Chrysopidae) to pyriproxyfen, a juvenile hormone analog
Authors: Chen T.‐Y. , Liu T.‐X.
Published: March 2003

Effects of pyriproxyfen (Knack), a juvenile analog, at three concentrations (10, 50 and100 mg [AI]/l), on survival and development of all immature stages of Chrysoperla rufilabris (Burmeister), were determined in the laboratory. Pyriproxyfen significantly reduced the survival rates when eggs, first and third instars were treated, but not when the second instars and pupae were treated. When eggs were treated, the two higher concentrations reduced the eggs viability by 33.3–50%, and only 0.0–6.7% developed to adults. The lowest concentration of pyriproxyfen (10 mg [AI]/l) caused high mortality on third instars, not on other stages, indicating the third instar was the most vulnerable stage. Pyriproxyfen had significant effects on development for all immature C. rufilabris that successfully developed to adults with variations among the developmental stages and concentrations. The overall developmental duration from eggs to adults when eggs, first, and third instars were treated were 2.6–4.2, 2.4–4.1 respectively, and 6.0–7.1 d longer than those in water control, respectively. However, the overall developmental durations from eggs to adults were 0.5–1.2 d shorter than in water control when the second instars were treated with pyriproxyfen. The compatibility of pyriproxyfen with natural enemies in integrated pest management programs is discussed.
Life history traits of Aphis gossypii Glover (Hom., Aphididae) reared on four widely distributed weeds
Authors: Perng J. J.
Published: March 2003

Variation in the life history traits of cotton aphids, Aphis gossypii Glover, reared on four widely distributed weeds, Ageratum houstonianum Mill., Bidens pilosa L. var. radiata Sch. Bip., Solanum nigrum L. and Spermacoce latifolia Aubl., were investigated. Cotton aphids were reared in the laboratory at 25°C. Each host plant had a distinct effect on aphid life history traits. Cotton aphids reared on S. nigrum had a significantly shorter developmental period, and age‐specific fecundity peaked early. In contrast, cotton aphids reared on S. latifolia had a long developmental period and low age‐specific fecundity. Cotton aphids that fed on B. pilosa and A. houstonianum displayed intermediate rates of growth and age‐specific fecundity. Because the curves of age‐specific fecundity (mx) and age‐specific net maternity (lx mx) on each host plant were close together, development time and the pattern of age‐specific fecundity were the major factors determining the population growth potential of the cotton aphid on each weed. As a result, the intrinsic rate of population growth for aphids reared on S. nigrum was significantly higher (rm=0.527 ± 0.011) than it was for aphids reared on S. latifolia (rm=0.194 ± 0.012).
Multispecies trapping of six pests of scots pine in Sweden and Poland
Authors: Johansson B. G. , Anderbrant O. , Sierpinski A.
Published: March 2003

Abstract:  Multispecies sex pheromone trapping (trapping of more than one species in the same trap) for the pine shoot moth Rhyacionia buoliana, the pine moth, Dendrolimus pini, the nun moth, Lymantria monacha, the pine beauty moth, Panolis flammea and the pine sawflies Diprion pini and Neodiprion sertifer was evaluated. The catch from traps baited with the pheromone of a single species was compared with the catch from traps baited with pheromones for several species. The catch in the multispecies traps was significantly reduced in comparison with the single species traps for Dendrolimus pini, L. monacha and N. sertifer. Neodiprion sertifer was most likely inhibited by the Diprion pini pheromone. A follow‐up study of Dendrolimus pini and L. monacha showed no pheromonal interference between them. Further studies are needed to evaluate the feasibility of multispecies monitoring. However, for practical applications a slight decrease in catch, due to pheromonal interference, could probably be tolerated as long as the catch reflects total population density.
Are San Jose scale (Hom., Diaspididae) pheromone trap captures predictive of crawler densities?
Authors: Badenes‐Perez F. R. , Zalom F. G. , Bentley W. J.
Published: March 2003

Abstract:  Abundance of San Jose scale (SJS), Quadraspidiotus perniciosus (Comstock), adult males and crawlers were monitored with pheromone traps checked weekly and associated sticky tape traps monitored biweekly, respectively, in commercial almond orchards in Kern County, California, USA, during 1999 and 2000. Regression analysis was used to determine if SJS crawler abundance could be predicted from SJS males captured on pheromone traps. No significant relationship (P > 0.05) was indicated for any generation or for all SJS captured for the season in 1999. With greater replication in 2000, statistically significant relationships were indicated for the first generation (r = 0.727; F = 25.712; P < 0.0001; n = 25) and for all generations (r = 0.777; F = 63.239; P < 0.0001; n = 25). An additional orchard in 2000 was divided into 18 1.21‐ha plots with different treatments applied. A statistically significant relationship was indicated for the first generation (r = 0.507; F = 11.769; P = 0.0016; n = 36) and second generation (r = 0.436; F = 7.972; p = 0.0079; n = 36). These results suggest that relative densities of SJS crawlers on sticky tapes can be estimated using SJS male trap captures for the first generation, and that this approximation is appropriate for whole orchards or for subplots within orchards as small as 1.21‐ha.
Significance of hibernated Thrips tabaci Lindeman (Thysan., Thripidae) adults in the epidemic of tomato spotted wilt virus
Authors: Jenser G. , Gáborjányi R. , Szénási A. , Almási A. , Grasselli M.
Published: March 2003

Abstract:  Tomato spotted wilt tospovirus (TSWV) was transmitted to indicator plants by Thrips tabaci, and was detected even in single specimens collected from different plants from September until May in Hungary. Consequently, the specimens of the hibernating generation are able to harbour TSWV from autumn until spring, for 6 months. They could infect the young seedling in the forced beds, or in the field in May, and thereby they have a significant role in the TSWV epidemic in spring under Hungarian climatic conditions.
Research Institute for Viticulture and Enology, Kecskemét, Hungary; Plant Protection Institute of Hungarian Academy of Sciences, Budapest, Hungary and Department of Plant Pathology, Cornell University, Geneva, NY, USA
Authors: Szegedi E. , S S. , üle . , Burr T. J.
Published: March 2003

The nonvirulent, antagonistic Agrobacterium vitis strain F2/5 was tested for the presence of tartrate utilization plasmid(s) which commonly occur in virulent A. vitis isolates. Following transformation of F2/5 plasmid DNA into Agrobacterium tumefaciens UBAPF2, an approximately 220 kbp plasmid coding for tartrate utilization was isolated. This plasmid, designated pTrF2/5, was also transferred by in planta mating between F2/5 and UBAPF2 and was maintained in a stable state in A. tumefaciens under nonselective conditions. pTrF2/5 could not be allocated into the known incompatibility groups described so far in Agrobacterium. Two transconjugant colonies also acquired an octopine utilization plasmid named pOcF2/5 which is related to the incRh1 Ti plasmids. Neither pTr nor pOc encodes for the tumour‐inhibiting ability of F2/5.
Cloning, Expression and Characterization of Protein Elicitors from the Soyabean Pathogenic Fungus Phytophthora sojae
Authors: Becker J. , Nagel S. , Tenhaken R.
Published: March 2003

The oomycete Phytophthora sojae is a severe pathogen of soybean. Several resistance genes against races of P. sojae exist in soybean but the nature of corresponding avirulence genes is unknown. Clones encoding four different isoforms of a protein elicitor from P. sojae (sojein 1–4) belonging to the class of acidic α‐elicitins have been isolated. These 98 amino acid proteins show high homology to elicitins from other Phytophthora species. The different sojein isoforms were expressed in Escherichia coli as His‐tagged fusion proteins. Purified sojein as well as recombinant sojein isoforms induce hypersensitive reaction (HR)‐like lesions in tobacco but are not active as race‐specific elicitors in soybean. However all sojein isoforms induce defence‐related genes like those encoding phenylalanine ammonia lyase, glutathione‐S‐transferase and chalcone synthase in tobacco and soybean plants and cell cultures. It is concluded that sojeins contribute to the induction of defence responses but that they are not involved in race specific recognition of the P. sojae races by soybean plants.
Possible Mechanisms Limiting Movement of Ralstonia solanacearum in Resistant Tomato Tissues
Authors: Nakaho K. , Hibino H. , Miyagawa H.
Published: March 2003

The distribution and appearance of Ralstonia solanacearum in the upper hypocotyl tissues of root‐inoculated tomato seedlings of resistant rootstock cultivar LS‐89 (a selection from Hawaii 7998) and susceptible cultivar Ponderosa were compared to clarify the mechanism that limits the movement of the bacterial pathogen in resistant tomato tissues. In stems of wilted Ponderosa plants, bacteria colonized both the primary and the secondary xylem tissues. Bacteria were abundant in vessels, of which the pit membranes were often degenerated. All parenchyma cells adjacent to vessels with bacteria were necrotic and some of them were colonized with bacteria. In stems of LS‐89 plants showing no discernible wilting symptoms, bacteria were observed in the primary xylem tissues but not in the secondary xylem tissues. Necrosis of parenchyma cells adjacent to vessels with bacteria was observed occasionally. The pit membranes were often thicker with high electron density. The inner electron‐dense layer of cell wall of parenchyma cells and vessels was thicker and more conspicuous in xylem tissues of infected LS‐89 than in xylem of infected Ponderosa or mock‐inoculated plants. Electron‐dense materials accumulated in or around pit cavities in parenchyma cells next to vessels with bacteria, and in vessels with bacteria. Many bacterial cells appeared normal in vessels, except for those in contact with the pit membranes. These results indicate that R. solanacearum moves from vessel to vessel in infected tissues through degenerated pit membranes and that restricted movement in xylem tissues was the characteristic feature in LS‐89. The limitation in bacterial movement may be related to the thickening of the pit membranes and/or the accumulations of electron‐dense materials in vessels and parenchyma cells.
Geographical Distribution of Bois Noir Phytoplasmas Infecting Grapevines in Croatia
Authors: Šeruga M. , Ćurković Perica M. , Škorić D. , Kozina B. , Mirošević N. , Šarić A. , Bertaccini A. , Krajačić M.
Published: March 2003

Visual symptom assessment, polymerase chain reaction amplification and restriction fragment length polymorphism analyses were used to detect and identify phytoplasmas infecting grapevines in Croatia. Samples were collected from different viticultural areas in order to examine geographic distribution of phytoplasmas throughout the country. Only phytoplasmas belonging to Bois Noir (subgroup 16SrXII‐A or stolbur) were found in vineyards of continental Croatia. The fact that no phytoplasmas were detected in Dalmatia and Istria was in accordance with the absence of grapevine yellows symptoms in these regions.
Function of Host and Fungal Metabolites in Resistance Response of Banana and Plantain in the Black Sigatoka Disease Pathosystem (Musaspp. –Mycosphaerella fijiensis)
Authors: Hoss R. , Helbig J. , Bochow H.
Published: March 2003

The host–pathogen interactions ofMusaspp. andMycosphaerella fijiensiswere investigated in order to determine the function of secondary metabolites within the pathosystem of the Black Sigatoka disease. The pentaketide metabolites flaviolin, 2‐hydroxyjuglone, juglone and 2,4,8‐trihydroxytetralone (2,4,8‐THT) of the pathogen were identified. The concentration of 2,4,8‐THT was significantly increased by application of the synthetic compound tricyclazole and by natural activators extracted from the intercellular space of leaf tissue of resistantMusacultivars. When inoculated host plants were treated with tricyclazole, extensive necrosis of both susceptible and resistantMusacultivar leaves were observed. Plant defence mechanisms of resistantMusacultivars were first detected as an activation of phenylalanine–ammonia lyase and the subsequent accumulation of post‐infectional substances which blocked fungal growth. These results indicated the bivalent importance of 2,4,8‐THT for host‐specific reactions, depending on its concentration at different stages of pathogenesis. Early activation of fungal 2,4,8‐THT metabolism by resistantMusacultivars caused necrotic micro‐lesions and elicitation of post‐infectional defence reactions leading to incompatibility between pathogen and host plant; growth of the fungus on susceptible cultivars caused necrotizing doses of 2,4,8‐THT only after the establishment of a compatible interaction and development of typical symptoms at late stages of pathogenesis.
Fusarium Blight of Kangaroo Paw (Anigozanthos spp.) caused by Fusarium chlamydosporum and Fusarium semitectum
Authors: Satou  , Ichinoe  , Fukumoto  , Tezuka  , Horiuchi
Published: March 2003

In 1990, an unreported blight occurred on kangaroo paw (Anigozanthos spp.) plants in Okinawa, southern Japan. Initially the disease developed in roots, and the symptoms of wilt and browning progressed upwards. The root growth was suppressed and the internal part of the root was discoloured to brown. Eventually flowering stalks and leaves showed a brown to black discoloration exhibiting blight symptoms. Two species of Fusarium were obtained from the diseased plant. The same symptoms appeared in plants transferred to soil and inoculated artificially with the two species of Fusarium. Based on the cultural characteristics and morphology, the two fungi were identified as Fusarium chlamydosporum Wollenweb. & Reinking and Fusarium semitectum auct. non Berk. & Ravenel. As no report was found on the blight of kangaroo paw plants, we suggest naming the disease as Fusarium blight of kangaroo paw.
Oospore Germination and Formation by the Late Blight Pathogen Phytophthora infestans in vitro and under Field Conditions
Authors: Strömberg A. , Boström U. , Hallenberg N.
Published: March 2003

The ability of the late blight pathogen Phytophthora infestans to form oospores in leaves of seven potato cultivars was examined at different incubation temperatures under controlled environmental conditions and under field conditions. At 10°C, the oospore formation in three intermediate‐resistant cultivars all differed significantly from each other (P < 0.05), with the lowest amount formed in cv. Asterix. This latter cultivar did not form oospores at any other temperature. Under field conditions oospores were formed abundantly in a naturally infected field. A significant date by cultivar interaction showed that P. infestans increased the oospore formation in foliage by time in cvs Columbo, Hertha and Matilda, whereas no significant differences between dates were found for other cultivars. The genetic structure of P. infestans in the naturally infected field plot, where oospores formed abundantly, was studied by using amplified fragment length polymorphism and a high genetic diversity was revealed. Oospore germination from two Scandinavian (A1 and A2) P. infestans isolates was stimulated in visible light and in 1 : 2 and 1 : 10 soil extract. The effect of light and nutrients on oosporogenesis is discussed.
The Ability of Barley Powdery Mildew to Grow in vitro
Authors: ARABI M. I. E. , JAWHAR M.
Published: March 2003

A technique was developed for the in vitro culture of Blumeria graminis f. sp. hordei, an obligate biotrophic pathogen of barley. Optimal growth occurred at pH 5.6 on a medium containing 39 gl–1 potato dextrose agar, 40 gl–1 shredded fresh barley leaves, 20 gl–1 sucrose, 13 mgl–1 kanamycin and 80 mgl–1 benzimidazole. At 20°C (90% relative humidity), conidia germinated 48 h after inoculation, producing an average colony diameter of 1 cm after 10 days. However, numerous colonies were present on the medium after 15 days. Light microscopy showed that there was a positive relationship between the amount of leaf in the medium and fungus growth. The fungus retained its virulence during 60 days of storage in vitro, and was able to infect barley. This is a useful and novel technique that could be beneficial in barley pathology breeding programs.
Flow Cytometric Analysis of Phialophora gregata Isolated from Soybean Plants Resistant and Susceptible to Brown Stem Rot
Authors: YEATER KATHLEEN M. , GRAU CRAIG R. , RAYBURN A. LANE
Published: March 2003

Flow cytometry was used to characterize isolates of Phialophora gregata, the causal organism of brown stem rot (BSR) in soybean, using the fluorescence intensity of YOYO‐1 stained conidia. The conidia were derived from isolates of P. gregata isolated from field‐grown soybean vascular tissue from two locations in Wisconsin. At each location, four soybean cultivars were grown. Two cultivars were susceptible to BSR and two cultivars were resistant to BSR. Ninety‐six isolates, one per plant, were characterized for DNA content. The stained conidia were analyzed with an EPICS XL (Coulter Corporation, Hialeah, Florida, USA) flow cytometer cell sorter with CICERO software (San Rafael, CA, USA). The isolates differed in their mean DNA content, ranging from 78.0 to 116.8 arbitrary units. Statistical analysis showed a significant difference in the DNA content variability of the isolates between the two locations. A notable difference in DNA content variability was observed between the isolates collected from the resistant cultivars between the two locations. However, no significant variation occurred in the DNA content of the isolates collected from susceptible cultivars within or between locations. The observed variation among the isolates is hypothesized to be due to the occurrence of separate populations of P. gregata and selection for mean DNA content that could colonize specific plant genotypes.
Calcium Enhanced Zoospore Production of Pythium myriotylum in vitro
Authors: Nyochembeng L. M. , Pacumbaba R. P. , Beyl Caula A.
Published: March 2003

Pythium myriotylum is the causal organism of Cocoyam Root Rot Disease (CRRD). Significant numbers of zoospores were induced within 1.5 h in cultures in Petri dishes containing P. myriotylum soaked in 0.01 M Ca++ and sterile deionized distilled water. Soaking solutions # 2 and # 3 inhibited the production of zoospores of P. myriotylum. This may be due to the delay in maturation of sporangia and the release of zoospores when the soaking solutions contain sucrose. Significant necrosis of detached cocoyam plantlet roots in 100 ml beakers confirmed the infection of zoospores of two `local white' cocoyam genotypes. Detached `yellow' cocoyam roots in 100 ml beakers of genotype RO3015 resisted infection of P. myriotylum with no necrosis of the inoculated roots, which may indicate resistance. This provides a quick and reliable pathogenicity test of P. myriotylum on susceptible cocoyam detached roots. Necrosis of inoculated detached cocoyam roots could be reliably used to screen cocoyam germplasm for resistance to P. myriotylum.
Activity of Azole Fungicides and ABC Transporter Modulators on Mycosphaerella graminicola
Authors: STERGIOPOULOS I. , DEWAARD M. A.
Published: March 2003

The antimicrobial activity of the azole fungicides cyproconazole and propiconazole as single active ingredients and in mixtures with the ATP‐Binding Cassette (ABC) transporter modulators rhodamine 6G, quercetin, quinidine, and verapamil and the strobilurin kresoxim‐methyl was assessed against the wheat pathogen Mycosphaerella graminicola. Interactions amongst these compounds were evaluated on germination and germ tube growth of pycnidiospores using the Colby and Wadley method. Water agar proved to be the best test medium since all pycnidiospores germinated within 24 h of incubation and apical germ tube growth dominated over bud formation by intermediate cells. Analysis with the Colby method revealed that interactions between the compounds in all mixtures tested on germination of pycnidiospores were additive. With regard to germ tube growth, mixtures of cyproconazole and verapamil or kresoxim‐methyl displayed a synergistic interaction. Analysis of mixtures of cyproconazole and kresoxim‐methyl with the Wadley method revealed that the interaction between the two compounds was purely additive. These results indicate that the Colby method overestimated the interaction between these two compounds in a mixture.
Selection of Kentucky Bluegrass for Drechslera poae Resistance under Greenhouse Conditions
Authors: Czembor E.
Published: March 2003

Resistance to leaf spot and melting out caused by Drechslera poae was evaluated in eight cultivars and seven breeding lines of Poa pratensis under greenhouse conditions. The results obtained in this study were compared with levels of resistance scored after natural infection under field conditions during 1994–1997 in sun and shade lawn maintenance, as described before. It was found that resistance assessed in the greenhouse as leaf spots in the three‐leaf seedling stage 10–14 days after the first inoculation (assessment I) and resistance assessed as severity of melting out on the crown 56 days after the first inoculation (assessment IV) showed the highest repeatability with the scores obtained in the field under sun and shade conditions during 1994–1997.
Production of Monoclonal Antibodies to Sugarcane Yellow Leaf Virus Using Recombinant Readthrough Protein
Authors: Korimbocus J. , Preston S. , Danks C. , Barker I. , Coates D. , Boonham N.
Published: March 2003

Yellow leaf syndrome (YLS) of sugarcane is associated with sugarcane yellow leaf virus (SCYLV), a member of the family Luteoviridae. A fragment of the coat protein and readthrough domain of SCYLV wasexpressed in a bacterial expression system. The resulting protein was purified and used to immunize mice for monoclonal antibody (MAb) production. Two MAbs, 3A2E3 and 2F7H5, were selected following the screening of hybridoma cells using both plate‐trapped antigen enzyme‐linked immunosorbent assay (PTA‐ELISA) and tissue blot immunoassay (TBIA). These MAbs can be incorporated into the TBIA assay currently used for the routine detection of SCYLV but could not be used in triple antibody sandwich enzyme‐linked immunosorbent assay (TAS‐ELISA). The two antibodies selected have slightly different specificities. Antibody 3A2E3 gave equivalent results to a polyclonal antiserum (raised to purified virus) in comparative testing using TBIA. The MAbs produced should provide a widely available, uniform reagent for SCYLV diagnosis with the potential to help manage YLS.
Digestibility and Compatibility of Mixed Diets and Faecal Consistency in Different Breeds of Dog
Authors: Meyer H. , Zentek J. , Habernoll H. , Maskell I.
Published: March 2003

The digestive capacity of dogs varying in body size was tested. Digestive experiments were conducted with 10 different canine breeds (n = 66) with body weights ranging from 4.2 to 52.5 kg with 4–9 individuals. The animals were fed a canned or a dry commercial diet with a constant dry matter intake of 13 g/kg BW/day, except in Irish wolfhounds, which ingested only 10 g dry matter with the canned diet. Faecal dry matter was around 14% (absolutely) higher for the dry diet compared to the canned food, with a tendency in the larger breeds towards higher faecal water contents, less favourable faecal quality and increased numbers of defaecations. The Irish wolfhounds, the largest breed tested, had faeces with considerably lower water contents compared to Labrador retrievers, indicating that body weight is not the only factor to be considered. There were only small differences in the apparent digestibility of crude nutrients amongst the breeds. Sodium and potassium absorption was higher when the dry diet was fed compared to the canned food. In conclusion, breed and individual factors have to be taken into account when performing tests with dog food. Test panels for evaluating commercial diets should include breeds of larger body size and higher sensitivity to dietary disorders.
Non‐specific Immunity and Ketone Bodies. I: In Vitro Studies on Chemotaxis and Phagocytosis in Ovine Neutrophils
Authors: Sartorelli P. , Paltrinieri S. , Agnes F.
Published: March 2003

The in vitro effects of the ketone bodies β‐OH‐butyrate (2.4 or 4.8 mmol/l) and acetoacetate (2.4 or 4.8 mmol/l) on the uptake of latex particles (1.09 μm) and chemotaxis were investigated in ovine neutrophils. Because the acetoacetate used was a lithium salt, the effect of 2.4 or 4.8 mmol/l lithium chloride was also tested. Neutrophils from eight non‐lactating, non‐pregnant ewes were studied. The uptake of latex particles, as measured by a spectrophotometric method, showed wide individual variation. The phagocytotic activity was unaffected by 2.4 mmol/l ketone bodies and LiCl, but it was significantly inhibited by 4.8 mmol/l β‐OH‐butyrate and activated by 4.8 mmol/l LiCl. The latter result could be masking an inhibitory effect of acetoacetate. Chemotactic movements of neutrophils, as evaluated in a modified Boyden chamber using homologous zymosan‐activated serum (ZAS) as a chemoattractant, were slightly but significantly reduced by a 2.4 mmolar concentration of the ketone bodies, administered singly or simultaneously, and by LiCl. We conclude therefore that the inhibitory effect of lithium‐acetoacetate could be due to its lithium component. The 4.8 mmol/l dose of acetoacetate and β‐OH butyrate significantly decreased chemotaxis only when both compounds were added simultaneously. No effect of 4.8 mmol/l LiCl was observed. These results suggest that ketone bodies, in particular β‐OH butyrate, could directly influence particle uptake and chemotaxis in neutrophils. Although other factors could decrease the efficiency of the immune system in ketotic ruminants, the effects of the ketone bodies on neutrophils functions may explain the high frequency of infectious disease during ‘ketotic syndrome’. The immunomodulatory effect of lithium needs to be evaluated further and it should be considered when testing lithium compounds.
Deep‐Freezing of Boar Semen in Plastic Film ‘Cochettes’
Authors: Eriksson B. M. , Rodriguez‐Martinez H.
Published: March 2003

The motility and membrane integrity of spermatozoa from nine boars frozen with a programmable freezing machine in plastic bags, ‘cochettes’®, and in ‘maxi‐straws’, in total doses of 5 × 109 spermatozoa/5 ml with glycerol (3 %) used as cryoprotectant, were assessed after thawing. A computer‐based cell motion analyser was used to evaluate sperm motility, while the integrity of the plasmalemma was assessed with fluorescent supravital dyes (C‐FDA/PI). The fertilizing capacity of the semen frozen in the two containers was investigated by inseminating (AI) gilts. Pregnancy was monitored by Doppler‐ultrasound, and the numbers of corpora lutea and viable embryos counted at slaughter, between days 30 and 38 after AI. The cochettes sustained the overall procedure of freezing/thawing (FT), with 30 min post‐thaw (PT) sperm motility being significantly higher than for straws, 46.9 vs. 39.5 %. The only significant difference in motility patterns detected when comparing the packages was a higher sperm velocity (VCL) in cochettes at 30 min PT. However, percentages of FT‐spermatozoa with intact membranes, detected with the supravital probes, were higher in maxi‐straws than in cochettes, 46.8 vs. 43.0 % (P < 0.05). There were no significant differences found in fertilizing capacity between spermatozoa frozen in maxi‐straws and those frozen in cochettes. The results indicate that although the deep‐freezing of AI‐doses of boar semen in large plastic bags is feasible, problems such as their inconvenient size for storage and inconsistent thawing must be solved before this type of container can be used for the commercial cryopreservation of boar semen.