bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Temperature and Photoperiod on the Development of Lupinus albus L. in a Controlled Environment
Authors: Keeve R. , Krüger G. H. J. , Loubser H. L. , Van Der Mey J. A. M.
Published: March 2003

An experiment to determine the effect of temperature and photoperiod on Lupinus albus under controlled environmental conditions was carried out, using the three Lupinus albus genotypes ‘Tifwhite’, ‘Esta’ and ‘Kiev’, and three temperature (10/20, 18/28 and 20 °C continuously) and two photoperiod (8 and 16 h daylength) regimes, in all combinations. Half of the seeds were vernalized for 21 days at 4 °C to alleviate the obligate vernalization requirement of Tifwhite. Although Esta and Kiev do not have obligate vernalization requirements, they were influenced by this vernalization period. Observations included the duration of the period from planting to seedling emergence, the duration of the period from planting to the beginning of flowering and the duration of flowering. The vernalization treatment accelerated plant development in all genotypes. The period from planting to emergence was shorter under the higher temperature regime. For all genotypes, the period from planting to flowering was shorter under the longer photoperiod, the same trend as would be expected for long‐day plants. Duration of flowering periods were, in contrast to pre‐flowering periods, shorter for all genotypes at cooler temperatures. The results of this study confirm that photoperiod does contribute to the growth period from planting to flowering in L. albus and that this species does behave as a long‐day plant.
Effect of Microclimatic Parameters at Different Sowing Dates on Capsule Production of Sesame (Sesamum indicum L.) in a Tropical Humid Region
Authors: Nath R. , Chakraborty P. K. , Chakraborty A.
Published: March 2003

An experiment was conducted during the summer seasons of 1993 and 1994 on sesame (Sesamum indicum L.) to study the effect of certain meteorological parameters on the capsule production efficiency of the main stem and branches of sesame cultivars at different sowing dates in alluvial (Entisol) soil of the tropical humid region in West Bengal, India. The highest capsule production by the main stem and the first, second and third primary branches in accrocentric order was observed for the crop sown on 19 February. The number of capsules on the main stem was reduced by 70.51 and 34.98 % when the crop was sown on 21 March and 28 April, respectively. The humidity profile at 50 days after emergence (DAE) and photosynthetically active radiation (PAR) at 70 DAE had direct positive effects on main stem capsule production. The variations of 38, 21 and 56 % in main stem contribution to capsule production might be explained by the temperature profile, relative humidity and PAR, respectively. Thecultivar Rama produced higher numbers of capsules in branches than Kanke‐1 and B‐67 at all times of sowing.
Nitrogen Uptake by Italian Ryegrass after Destruction of Non‐fertilized Set‐aside Covers at Different Times in Autumn and Winter
Authors: Clotuche P. , Peeters A.
Published: March 2003

The introduction of the European set‐aside into the rotation can modify the nitrogen availability for subsequent crops. With a view to evaluating this effect, three non‐fertilized covers were sown in May 1995. These covers were ploughed in at three different times: October 1995, December 1995 and March 1996. The ploughed‐in nitrogen quantities did not vary greatly with destruction time. The greatest quantities were incorporated into red clover plots and the smallest quantities into perennial ryegrass plots. The C/N of perennial ryegrass was on average 24 and that of red clover 14.

The soil cover by clover just before ploughing is significantly related to the ploughed‐in nitrogen quantities.

An Italian ryegrass was sown as the subsequent crop to the set‐aside. Overall, during the whole year 1996 and 1996–1997, there was no difference between the yields for different destruction times except for the first cut of 1996.

The highest production was obtained after red clover and the lowest after perennial ryegrass. The relationship between the nitrogen amount or C/N of the ploughed‐in material and the nitrogen export for the annual harvest of Italian ryegrass showed highly significant correlations in 1996 as well as for the 2‐year harvest. Two multiple regressions were calculated in order to take into consideration the characteristics of the ploughed‐in material of the set‐aside.

The measured percentage of soil cover by clover before ploughing and the annual nitrogen export of Italian ryegrass were also significantly related in 1996 and for both years.
Morphological Classification of Traditional Philippine Upland Rice Cultivars in Upland Nurseries Using Cluster Analysis Methods for Recommendation, Breeding and Selection Purposes
Authors: Schlösser I. , Kranz J. , Bonman J. M.
Published: March 2003

Using eight morphological parameters with six cluster analysis methods, a set of 21 traditional and four improved Philippine upland rice cultivars (cvs) could be separated into five groups: (1) improved semi‐dwarf plant type, (2) improved or ‘moderately modified’ (short) Indica plant type, (3) traditional tall Indica plant type, (4) traditional tall Japonica plant type and (5) traditional short Japonica plant type. The results emphasized the importance of the separation into Indica and Japonica plant types, but the cultivars could be classified more accurately using growth characteristics such as tillering ability, followed by plant height and leaf area parameters. The clusters containing Indica cvs consistently showed a higher tiller number per plant, a higher growth stage (DC classification) and narrower leaves than clusters with Japonica cvs. The parameters culm length, plant height, leaf area, leaf length and width were represented in subgroups with both long and short expression of the respective characteristic. Use of the existing variability of morphological traits within the group of traditional upland rice cvs should be beneficial in recommendation, breeding, selection and development of upland rice cvs for the different rice ecosystems as well as for the upland rice/rice blast pathosystem.
Chemical Manipulation of Reproductive Efficiency of Chickpea (Cicer arietinnum L.) by Triadimefon in Relation to Changes in Ethylene
Authors: Saxena D. C. , Abbas S. , Sairam R. K.
Published: March 2003

Reproductive efficiency was successfully manipulated by the application of different concentrations of triadimefon at pre‐flowering, flowering and post‐flowering stages in chickpea (Cicer arietinum L.). Triadimefon improved the parameters determining reproductive efficiency. Yield was significantly improved due to reductions in flower and pod abscission by the application of triadimefon, which also lowered the ethylene levels in leaves, flowers and pods and delayed senescence. These findings suggest a relationship between ethylene level and reproductive efficiency in chickpea. Further, they indicate that triadimefon can be used for chemical manipulation of the reproductive efficiency of chickpea under field conditions.
Optimierung der Produktion von Wintergetreide zur Bioethanolherstellung durch unterschiedlich intensive Anbauverfahren
Authors: Rosenberger A. , Kaul H.‐P. , Senn T. , Aufhammer W.
Published: March 2003

Improving the production of winter cereals for bioethanol by cultivation with varied intensity

The investigations were based on biennial field trials carried out at two locations comprising the factors location/previous crop, winter cereal genotype (rye cv. ‘Farino’,triticale cv. ‘Modus’, wheat cv. ‘Batis’) and production intensity level. One agronomical focus was to replace the mineral N‐supply due to its energetic relevance, by either the residues of legumes, or stillage, a processing residue containing organic N. The measurement included the crop yield ha−1, the bioethanol exploitation dt−1 and the bioethanol yield ha−1. The last was closely correlated to the grain yield and thus dominated by intensity level. Highest bioethanol yields with an average peak at 4022 l ha−1, always occurred at the highest intensity level. Bioethanol exploitation however, was mainly determined by the genotype. The cultivars showed significant exploitation and yield differences. An adequate bioethanol exploitation was observed with the wheat cv. Batis in contrast to diminished grain and bioethanol yields. Considering bioethanol exploitation and bioethanol yield, the triticale cv. Modus was the outstanding genotype. Despite high grain yields, the bioethanol yields of the rye cv. Farino stayed mean, because of a genotypic lowered bioethanol exploitation. Comparing the approaches of mineral nitrogen substitution, legume N was successful, whereas stillage fertilizing, according to the examined conditions, resulted in ample decreased grain and bioethanol yields ha−1.
Ionic Ratios and Crop Performance. I. Vanadate and Phosphate on Soybean *
Authors: Olness A. , Nelsen T. , Rinke J. , Voorhees W. B.
Published: March 2003

Resin‐extraction techniques obtain a suite of extractable elements/ions from a single sample. They are, therefore, capable of characterizing interactions between nutrients and toxic ions on plant growth and of aiding in identification of genetic characteristics of plants required for optimal resource use efficiency. To demonstrate the usefulness of this technique, a field experiment was established on a 3.24‐ha site that included five soil mapping units. The site was divided into three equal portions and planted with corn (Zea mays L.), soybean (Glycine max L. Merr.) and wheat (Triticum aestivum L.). Crops were rotated annually and each rotation was divided into 360 plots measuring about 3 m by 30 m. Soybean varieties designated 9091 and 9061 were planted in consecutive strips of 4 rows at 0.75 m row spacing. Soil samples were extracted with anion and cation resin exchangers. Resin exchangers were eluted with acid and the eluates examined by inductively coupled plasma atomic emission spectroscopy. Soil samples were also examined for bicarbonate extractable P, organic C, total N and pH. Seed yields were different between varieties and soils (P < 0.05). Seed yields ranged from about 2,390–3470 kg ha‐1. Seed yields of variety 9061 declined by as much as 20 % (about 540 kg ha‐1) as the resin extractable V:(V + P) ratio increased to 0.15 mol mol‐1. Resin extractable V differed between soil mapping units. Soil bicarbonate extractable P, organic C, total N and pH had minimal effects on seed yield.
Influence of Soil Moisture and Fertilizer Potassium on the Vegetative Growth of Mungbean (Vigna radiata L. Wilczek) and Cowpea (Vigna unguiculata L. Walp)
Authors: Sangakkara U. R. , Frehner M. , Nösberger J.
Published: March 2003

Tropical food legumes are grown in a wide range of environments, and water stress is considered the principal environmental factor limiting growth and yield. Potassium fertilizer mitigates the impact of water stress in plants. However, the benefits of potassium in overcoming stress in tropical food legumes have not been investigated in comparative studies. The purpose of this study was to determine the benefits of potassium in overcoming water stress in mungbean and cowpea, two important tropical food legumes with different adaptabilities to soil moisture regimes. The experiment carried out under controlled conditions placed emphasis on vegetative growth and selected physiological parameters. The impact of potassium was different in the two legumes grown at optimal and suboptimal soil moisture. Potassium increased shoot growth of mungbean to a greater extent than in cowpea under suboptimal moisture conditions. The roots of cowpea showed a greater response to potassium fertilizer than in mungbean under suboptimal soil moisture. The plant water relations and photosynthetic rates of mungbean were improved to a greater extent by potassium under suboptimal soil moisture than those of cowpea. Although differences were observed in the responses of the vegetative growth of these species to moisture and potassium, in overall terms potassium promoted growth of both species when subject to suboptimal soil moisture. While field studies are required to validate the results, the application of potassium fertilizer can be considered a significant factor in overcoming soil moisture stress in these legumes commonly grown in tropical cropping systems.
Carbon Isotope Discrimination and Productivity in Field‐Grown Barley Genotypes
Authors: Teulat B. , Merah O. , This D.
Published: March 2003

Five barley genotypes of different origins were used to examine the relationships between carbon isotope discrimination (Δ) and grain yield, yield components, dry aerial biomass and harvest index under rainfed and irrigated Mediterranean conditions. High positive correlations were found between Δ and grain yield and harvest index under both water conditions, suggesting that Δ may represent efficiency of dry matter partitioning to the grain. This hypothesis was also supported by the positive correlation found between Δ and thousand‐grain weight when all the data were considered. The two drought‐tolerant genotypes LM2887 and Tadmor presented the smallest difference between the two treatments for traits related to productivity as well as the highest Δ values. These results highlight the potential of Δ as a selection criterion in barley breeding in Mediterranean regions. They also encourage the study of the genetics of Δ and the identification of molecular markers linked to its variation in available progenies derived from crosses between the genotypes used in the present paper.
Sensitivity of Crops to Increased Ultraviolet Radiation in Northern Growing Conditions
Authors: Hakala K. , Jauhiainen L. , Koskela T. , Käyhkö P. , Vorne V.
Published: March 2003

Crops growing at high latitudes are adapted to low intensities of solar ultraviolet B radiation (UV‐B). As a result of destruction of stratospheric ozone layer especially at the Polar Regions of the globe, the intensity of UV‐B is projected to increase at high latitudes. In order to find out the consequences of increased UV‐B on crops, the sensitivity of different varieties of barley, wheat, oats, clover, timothy, meadow fescue, tall fescue and potato was tested in Jokioinen, Finland. The experiment was conducted in the field, under natural light, with a continuous 30 % increase in UV‐B. Both increased UV‐B and the control with slightly increased UV‐A radiation affected the number of lateral shoots in cereals, and the specific leaf area and the content of phenolic substances in grasses. The effects varied according to plant variety and time of growing season. However, no visible damage, nor changes in biomass and yield production were found in any of the crops. Long‐term effects on, e.g. genetic stability and germination of crop seed remain to be studied.
Effect of Sodium Chloride Salinity on Seedling Emergence in Chickpea
Authors: Esechie H. A. , Al‐Saidi A. , Al‐Khanjari S.
Published: March 2003

Although laboratory (Petri dish) germination as an estimate of seed viability is a standard practice, it may not give an accurate prediction of seedling emergence in the field, especially when saline irrigation water is used. Experiments were conducted to investigate seedling emergence in two chickpea cultivars (ILC 482 and Barka local) in response to varied salinity levels and sowing depths. Seeds were sown in potted soil at a depth of 2, 4 or 6 cm. The salinity treatments were 4.6, 8.4 and 12.2 dS m–1. Tap water (0.8 dS m–1) served as the control. Depth of sowing had a significant effect on seedling emergence. Seeds sown 6 cm deep showed the lowest seedling emergence. Similarly, salinity had an adverse effect on seedling emergence. The lowest seedling emergence percentages were obtained at the highest salinity treatment (12.2 dS m–1). The interaction between salinity treatment and seeding depth was significant. Hypocotyl injury was implicated as a possible cause of poor seedling emergence in chickpea under saline water irrigation and was less severe when pre‐germinated seeds were used. ILC 482 appeared to be more tolerant to salinity than Barka local, suggesting that breeding programmes involving regional exchange of germplasm may be helpful.
Temperature, Osmotic Pressure and Seed Treatments Influence Imbibition Rates in Sorghum Seeds
Authors: Kader M. A. , Jutzi S. C.
Published: March 2003

Imbibition is an essential part of the germination process and is affected by various environmental factors. The effects of temperature, seed treatment, storage and osmotic pressure on primed and untreated sorghum seed were examined. The potential influence of NaCl‐based seed‐soaking treatments was also investigated. Experiments on sorghum seeds showed that imbibition rates were higher in untreated than in primed seeds after more than 24 h of soaking and that a rise in priming temperature increased imbibition to a greater extent in the former. The influence of imbibition in regulating the seed response to priming, heat and osmotic stress is discussed.
Logistic regression approach to modelling the variability of recombination rate
Authors: Szyda By J. , Simianer H. , Lien S.
Published: March 2003

The objective of the paper is to quantify the relationship between recombination rate and factors such as ‘sex of sperm’, paternal halfsib family, and individual, using logistic regression modelling. The analysed data set consists of 2214 single bovine sperm cell samples. Haplotypes at each single sperm were determined at eleven marker loci forming eight intervals located on chromosomes 6, 23 and X/Y. The experimental design comprises six paternal halfsib families. Six logistic regression models are fitted to the data from each interval. Departure from commonly assumed homogenous recombination is detected for one marker interval on chromosome 23 – influence of individual and ‘sex of sperm’ by family interaction, and for both intervals mapped to sex chromosomes – influence of ‘sex of sperm’ and paternal halfsib family.
Prevalence and inheritance of canine elbow dysplasia in German Rottweiler
Authors: Beuing R. , Mues CH. , Tellhelm B. , Erhardt G.
Published: March 2003

A total of 2114 scores of elbow arthrosis from the official screening programme of the German Rottweiler Breeding Association (ADRK) were analysed in respect of prevalence and genetic disposition. 45.8% showed no signs of arthritis, 40.6% were scored in Grade 1 with minor osteophytes and 13.6% were affected by arthritis of clinical relevance (Grade 2 and 3). REML estimates showed a heritability of 28% and a litter variance of 6.4%. The only significant environmental fixed effect was gender. 39.1% of the male and 51.5% of the female were free from ED which corresponds with 19.2% of the male and only 8.8% of the female in the critical ED classes of Grade 2 and 3. Differences between the years of examination could be explained by genetic gain. Month of birth as well as age at examination, in the range covered by this study, was not significant. It was stated that the effect of bodyweight should be tested before starting a breeding programme.
Genetic distance and classification of domestic animals using genetic markers
Authors: Nagamine  , Higuchi
Published: March 2003

Genetic distance is used to classify and elucidate the evolutionary relationship between populations, such as species, which have been diverging for a long period. The properties of genetic distance measures in livestock classification have hitherto not been investigated. We used simulation studies to compare the accuracy of eight genetic distance measures to classify recently diverged populations. The effect of varied population sizes from generation to generation were also taken into account. Comparatively better results are obtained from Nei’s standard distance with two alleles at each locus and from Nei’s DA distance with four alleles at each locus under various conditions. However, the difference in accuracy among distance measures was small and very high correlations were shown. The number of alleles at each locus had a greater effect on accuracy than the number of loci or type of distance measures. It indicates that highly polymorphic markers, such as DNA microsatellite, are powerful tool to improve the accuracy in classification of domestic animals. The six distance measures had a linear relationship with generation number at constant population size. None of the distance measures, however, showed a linear relationship when population size varied. The effect of fluctuating population size on the average distance was obvious over the first few generations but declined when the number of generations was increased.
Effects of models with finite loci, selection, dominance, epistasis and linkage on inbreeding coefficients based on pedigree and genotypic information
Authors: CURIK INO , SÖLKNER JOHANN , STIPIC NIKOLA
Published: March 2003

Considering the effects of selection, dominance, epistasis and linkage, a stochastic computer simulation was performed to study how well inbreeding coefficients calculated from pedigree (fped) and genotypic frequencies (fhet) correspond to the inbreeding coefficient that is defined as the proportion of autozygous loci in the modelled genome (i.e. the level of autozygosity, faut). Although in random mating populations all three inbreeding coefficients show almost (with slight deviations in models with two loci) the same expectation, they represent three separate variables. First, faut, fped and fhet responded differently to selection, dominance, epistasis and linkage. Second, they did not have the same standard deviations, which means that the effects of random drift, especially in models under selection, were not affecting all three coefficients in the same way. Finally, they were not always defined in the same domain. With selection as the most important factor responsible for the observed discrepancies, the bias (discrepancy) was present in both directions, thus leading to overestimation or underestimation of the observed level of autozygosity depending on the genetic model, linkage and initial gene frequency. Variation of the autozygosity level (between replicates) was increased notably in models with additive inheritance under selection and was an additional potential source of bias. Thus, when the trait is, to a large extent, controlled by a finite number of loci and when selection is present, the bias in the estimation of the autozygosity is likely to occur and caution is necessary whenever conclusions are based on inbreeding coefficients estimated from the pedigree or decrease in heterozygosity.
Growth performance and health status in weanling piglets fed spray‐dried porcine plasma under typical Northern European conditions
Authors: VAN DIJK A. J. , MARGRY R. J. C. F. , VAN DER LEE A. G. , HEMKE G. , BEYNEN A. C.
Published: March 2003

The effect of inclusion of spray‐dried porcine plasma (SDPP) in diets for weanling piglets was studied. The objectives were to determine whether SDPP would have positive effects on post‐weaning piglet performance and health under typical Northern European conditions. In experiment 1, 160 weanling piglets were assigned randomly to a control diet or a diet containing 3% SDPP, which was added at the expense of both fishmeal and dried skim milk. In experiment 2, 264 weanling piglets were assigned to a control diet containing whey protein, a diet without whey protein but with SDPP or a diet containing both whey protein and SDPP. In essence, SDPP was added to the test diets at the expense of either whey protein or fishmeal. Piglets were fed the diets for 3 weeks. In experiment 1, the piglets fed the SDPP diet had a 7% higher average daily gain (ADG) and a 4% lower feed conversion ratio (FCR) (p < 0.05) during the first 3 weeks after weaning than did those fed the control diet. There were no differences in leucocyte counts or γ‐globulin. In experiment 2 there were no significant differences in ADG and FCR among the dietary treatments. It is concluded that low amounts of SDPP in weanling diets can have positive effects on growth performance under Northern European conditions.
In situ rumen degradation and in vitro gas production of some selected grains from Turkey
Authors: Umucalilar H. D. , Coşkun B. , Gülşen N.
Published: March 2003

An investigation of the dry matter degradability (DMD) and effective dry matter degradability (EDDM) was performed for barley, wheat, rye, corn, triticale and oat samples, using the Nylon‐bag technique. Gas production (GP), metabolizable energy (ME) and in vitro organic matter digestibility (IVOMD) were also studied by using Hohenheim gas test. The DM from barley, wheat, rye and triticale was digested rapidly in the rumen, and, at the 48 h of incubation, degradability was found to be approximately about 80%. The higher degradability observed for these grains than for oats and corn was attributable to the structure of these grains. In contrast, DM of corn and oats was degraded very slowly and reached 66.7 and 66.5 at 48 h, respectively. Effective degradability values of barley, wheat, rye, corn, triticale and oats were determined to be 61.4, 69.0, 64.0, 41.7, 66.7 and 58.6% in 5% rumen outflow rate, respectively. At the end of the 48 h incubation, total gas productions in barley, wheat, rye, corn, triticale and oats were estimated to be 83.6, 87.2, 87.5, 83.5, 85.8 and 63.9 ml/200 mg DM, respectively. The mean ME values of these grains calculated from cumulative gas amount at 24 h incubation were 11.8, 12.1, 12.3, 10.9, 12.4 and 10.2 MJ/kg DM, respectively. In vitro digestible organic matter of barley, wheat, rye, corn, triticale and oats were estimated to be 85.0, 87.3, 88.2, 79.5, 89.0 and 72.6%. Percentage overall EDDM (k=5%) of barley, wheat, rye, triticale and oats was positively correlated with in vitro GP at 6 h, cumulative GP at 24 h and total GP at 48 h (p<0.05). As a result, in situ dry matter degradation of grains showed great differences depending on the chemical compositions. In situ EDDM of grains may be predicted from in vitro gas production parameters.
Teratogenic effects of chronic ingestion of high levels of vitamin A in cats
Authors: Freytag T. L. , Liu S. M. , Rogers Q. R. , Morris J. G.
Published: March 2003

High concentrations of retinoids occur in some commercial cat food formulations as a result of the use of animal liver as an ingredient. Our objective was to study the teratogenic potential of dietary vitamin A in cats. We investigated the incidence of birth defects in kittens of queens given diets with retinyl acetate concentrations of 6000, 306000, or 606000 retinol equivalents (RE)/kg diet (control, 306K, or 606K groups, respectively) for approximately 3 years [1 RE=1 μg retinol=3.3 International Units (IU)]. Each group comprised 12–15 age‐matched, nulliparous domestic short‐haired queens that were exposed to toms. There were a total of 396 kittens born in 97 litters. Pregnancy rate, number of kittens per gestation and gestations per year were not significantly different among treatment groups. A total of 2, 5 and 11 malformed kittens occurred in the control, 306K and 606K groups, respectively. Malformations included cleft palate, cranioschisis, foreshortened mandible, stenotic colon, enlarged heart and agenesis of the spinal cord and small intestine, which are typical foetal defects consistent with ingestion of excess retinoids in other species. This study demonstrated that a concentration of 306000 RE/kg diet has a potential for causing birth defects in the kittens.
Efficacy of Xylocoris flavipes (Reuter) (Het., Anthocoridae) to suppress Prostephanus truncatus (Horn) (Col., Bostrichidae) in traditional maize stores in southern Togo
Authors: Helbig J.
Published: March 2003

In the course of three storage periods (1988–90) the predacious insects that occur in traditional maize stores in southern Togo were observed and their relationship to the introduced pest Prostephanus truncatus was investigated. The bug Xylocoris flavipes, a predator on a wide range of post‐harvest pests, was the only one observed regularly and in higher numbers. Laboratory trials with P. truncatus showed that the larvae were preyed on, and no preference for any one of the three instars was detected. On average, 7.3 pest larvae were killed by larvae or adults of the predator. In glass jar trials on loose maize X. flavipes reduced the numbers of P. truncatus by 57.6% after 8 weeks. The losses and damage were reduced by 50 and 17.6%, respectively. Observations in traditional maize stores indicated a tendency to decreasing populations of X. flavipes when populations of P. truncatus increased, presumably due to the unfavourable environmental conditions created by the pest. Therefore, it is concluded that X. flavipes does not play an important role in the control of this pest.
Lydella thompsoni Herting (Dipt., Tachinidae), a parasitoid of the European corn borer, Ostrinia nubilalis Hbn. (Lep., Pyralidae) in Slovakia, Czech Republic and south‐western Poland
Authors: Cagáncaron L’. , Turlings T. , Bokor P. , Dorn S.
Published: March 2003

This paper shows that, within Central Europe, parasitism of the European corn borer (ECB) by the tachinid parasitoid, Lydella thompsoni (LT) increased from 0.47 to 1.49% in south‐western Poland (51°03′N), to 4.31–21.95% in eastern Slovakia (48°20′N). The synchrony between the parasitoid LT and its primary host, the ECB, was studied in Central Europe under conditions where the host is univoltine, but the parasitoid is bivoltine. A cumulated total of more than 400 LT was field‐collected from overwintering ECB larvae. The parasitoid hibernated as larva inside the host. Pupation started in the second half of the following March and 50% of pupation was surpassed in the first half of April. The first parasitoid adults emerged at the end of April and the majority at the beginning of May. Development threshold temperatures for 50% pupation was determined to be 2.7°C, and for 50% adult emergence 5.0°C; the respective thermal constants were 178.8–179.8 and 237.7–251.8 Celsius degree‐days. Emerged adults did not parasitize overwintered ECB larvae in spring, hence there must be an alternate host for the first generation of LT in areas of univoltine life cycle of the ECB. Parasitization of the ECB larvae by LT continued until the end of July. The first parasitoid adults from this second generation emerged in the second half of August. By the end of the season, nearly one‐third of LT adults had emerged. The rest of this generation apparently overwintered in the larval stage.
Dyed baits distribution in nests of Atta sexdens L. (Hym., Formicidae)
Authors: Pretto D. R. , Forti L. C.
Published: March 2003

Dyed baits distribution in colonies of Atta sexdens was studied so as to test the hypothesis of uniform distribution. Three medium‐ to large‐size (34–90 m2) colonies were used for the experiment; coloured dyed baits material was made available at the foraging orifices, which had previously been mapped out and grouped into three hypothetical sectors. After 24 h the colonies were killed and the nests excavated; the fungus was removed from each of the chambers for observation of the presence or absence of dyed baits. It was shown that coloured material from each of the different sectors was found in all the fungus chambers, thus confirming the hypothesis.
Resistance level in Scots pine clones and artificial introductions of Tomicus piniperda (Col., Scolytidae) and Leptographium wingfieldii (Deuteromycetes)
Authors: Bois E. , Lieutier F.
Published: March 2003

Scots pine trees belonging to clones considered to be resistant or susceptible after mass inoculations of Leptographium wingfieldii, a fungus associated with Tomericus piniperda, were submitted to a low density of fungal inoculations or beetle insertions. The length of the phloem‐induced reaction zone, the fungal extension and fungal density inside the reaction zone, and the length of maternal galleries of T. piniperda were measured. The length of the phloem reaction zone never differed between resistant and susceptible trees. The density of the fungus mycelium in histological sections of the phloem, and the length of the maternal galleries in the reaction zone were higher in the susceptible trees than in the resistant ones. These factors could be good indicators of resistance of Scots pine to mass attacks.
Host preference and host suitability in an egg‐pupal fruit fly parasitoid, Fopius arisanus (Sonan) (Hym., Braconidae)
Authors: Quimio  , Walter
Published: March 2003

The relative oviposition rate of the parasitoid Fopius arisanus (Sonan) was investigated across three frugivorous tephritid species, Bactrocera tryoni Froggart, Bactrocera jarvisi (Tryon) and Bactrocera cucumis French. Choice and no‐choice tests were both used. The suitability of these three species for sustaining larval development and survival to the adult stage was also assessed. Fopius arisanus parasitized all three tephritid species, regardless of the method of exposure, but showed stronger preference for B. tryoni and B. jarvisi over B. cucumis. Superparasitism was extremely rare. Successful development of F. arisanus varied across host species. Bactrocera tryoni yielded significantly more parasitoids than B. jarvisi, but no wasps emerged from B. cucumis puparia. Tests were set up in replicated trials, but results were not homogeneous across trials. We discuss the host relationships of F. arisanus with reference to this variation and in relation to host suitability for larval development.
Effect of some characters on the population growth of mite Varroa jacobsoni in Apis mellifera L colonies and results of a bi‐directional selection
Authors: Lodesani M. , Crailsheim K. , Moritz R. F. A.
Published: March 2003

Two lines of honey bees (Apis mellifera ligustica) were selectively propagated by instrumental insemination using the population growth of the Varroa mite as a criteria. Different infestation rates are at least partially genetic since selection produced significant bi‐directional differences between lines over a period of three subsequent generations. There was no correlation between several behavioural and physiological characteristics which are potentially associated with Varroa resistance (hygienic behaviour, physical damage to mites, infertility of the intruding mites) and the development of the Varroa population after artificial infestation. There was a positive significant correlation between the total mites in the colonies and the amount of reared brood. Colony infestation was also positively correlated with the amount of honey harvested.
The pest termites of South America: taxonomy, distribution and status
Authors: Constantino R.
Published: March 2003

Abstract: A total of 77 species of termites have been reported as structural or agricultural pests in South America. These records are reviewed, with indication of the damage they cause, their pest status, distribution and sources of information. Among these, 40 species are reported as structural pests, 53 species as agricultural pests and 15 species as both. However, only 18 species are considered major pests and the status of most of the others is uncertain. Uncertainty about status is much higher among agricultural pests. Specific taxonomic problems are discussed and distribution maps of the main pest genera and species are presented. The most important structural pests are the introduced Coptotermes havilandi and Cryptotermes brevis and the native Nasutitermes corniger. Reticulitermes was introduced into Uruguay and Chile, where it is the only serious pest. The main agricultural pests are Heterotermes spp., Nasutitermes spp., Cornitermes spp., Procornitermes spp. and Syntermes spp., and the most affected crops are sugarcane, upland rice and eucalyptus.
Calibration of an EAG system to measure airborne concentration of pheromone formulated for mating disruption of the pink bollworm moth, Pectinophora gossypiella (Saunders) (Lep., Gelechiidae)
Authors: Koch U. T. , Cardé A. M. , Cardé R. T.
Published: March 2003

Abstract: Electroantennogram (EAG) devices, used to measure airborne pheromone density in mating disruption experiments, so far have provided only ‘relative units’ of concentration rather than absolute concentration values. This paper describes a technique to measure the amount of pheromone delivered by calibration syringes into the Kaiserslautern EAG pheromone measurement device, thereby allowing such relative units of concentration to be converted into absolute concentrations. The synthetic pheromone used in these calibrations is of Pectinophora gossypiella (Saunders), the pink bollworm moth, and consists of a 1 : 1 mix of (Z,Z)‐ and (Z,E)‐7,11‐hexadecadienyl acetates. The syringe, driven as in field use, delivers its pheromone–air mixture into a glass capillary where it is adsorbed. The amount of pheromone trapped is measured by gas chromatography. The results show a linear relationship between the ratio of pheromone : silicone oil in a syringe and the pheromone concentration in the air puffs it generates. Efficacious mating disruption of P. gossypiella in cotton occurs with 10−6 relative EAG units, which corresponds to an aerial pheromone density of 1.7 ± 0.15 ng/m3.
Chlorpyrifos spraying of no‐tillage corn during tasselling and its effect on damage by Helicoverpa zea (Lep., Noctuidae) and on its natural enemies
Authors: Filho M. M. , Della Lucia T. M. C. , Cruz I. , Guedes R. N. C. , Galvão J. C. C.
Published: March 2003

Abstract:  Corn plants were twice sprayed at 3‐day intervals during tasselling to evaluate the effect of chlorpyrifos on ear damage by H. zea and also on the populations of the natural enemies associated with this moth. The abundance of H. zea eggs and larvae and of predators on the whole plant, the egg parasitism by Trichogramma pretiosum Riley and the percentage of injured ears were sampled weekly. Chlorpyrifos did not show any significant effect on population levels and on ear damage by H. zea. Natural parasitism of eggs ranged from 52 to 75% and did not differ between treated and untreated plots; furthermore, the percentage of non viable eggs and adult emergence were not influenced by insecticide application. Among the predators found in the plots, Doru luteipes was not affected by spraying, whereas the abundance of Orius sp. decreased 21 days after insecticide application. The frequency of the ant Pheidole sp. was not affected by chlorpyrifos; however, foraging activity of Crematogaster sp. on treated plots was rapidly reduced and remained low during the following 2 weeks. The small number of damaged ears suggests that the insecticide did not affect the efficiency of the natural enemies of H. zea.
Studies on the possible competition for pollen between the honey bee, Apis mellifera sudanensis, and the imported dwarf honey bee Apis florea (Hym., Apidae) in North‐Khartoum (Sudan)
Authors: El Shafie H. A. F. , Mogga J. B. B. , Basedow Th.
Published: March 2003

Abstract:  Based on identification of collected pollen, in the area of North Khartoum, 21 plant genera (ca. 21 spp.) proved to be the main pollen sources for the honey bee Apis mellifera sudanensis. The imported dwarf honey bee Apis florea exploited 11 of these. The main pollen flow in the study area occurred between early December and late March. This is reflected by the amount of pollen collected by colonies of A. mellifera sudanensis. In spite of observations conducted soon after the introduction of A. florea, which gave hints of competition between the two bee species, further studies showed that A. mellifera sudanensis and A. florea do seem to coexist. This coexistence is based on different daily rhythms of pollen collection. A. mellifera collected pollen of Acacia seyal, date palm, and onions early in the morning (and partly in the late afternoon), while A. florea started pollen collection mostly later in the morning and ended it earlier in the afternoon. But in contrast to A. mellifera, A. florea was collecting pollen all day without interruption, even at very high air temperatures. Niche overlap (concerning the times of visits to flowers) between the two bee species was very low in date palms, and of medium importance in Acacia seyal. But it is remarkable that in total, A. florea is always present in higher numbers than A. mellifera sudanensis, on flowers. The significance of the introduction of A. florea to Sudan for pollination is discussed.
Influence of hunger level and prey density on searching behaviour of the reduviid predator Rhynocoris marginatus (Fabricius) (Het., Reduviidae)
Authors: Claver M. A. , Ambrose D. P.
Published: March 2003

Abstract: Mechanism underlying the searching behaviour of the predator Rhynocoris marginatus in different levels of hunger and at different densities of its prey Spodoptera litura was studied within an experimental arena. Starved for 1‐day R. marginatus travelled 2.34 times longer distances than starved for 4‐day ones to find prey in the four prey density arenas. Total distance travelled by R. marginatus at four S. litura density arenas was 0.4 times shorter than that in one density regime. Searching speed of 4‐day hungry R. marginatus was 2.44 times greater than 1‐day hungry R. marginatus. R. marginatus at four S. litura density regimes searched at 2.43 times higher speeds than R. marginatus at one density regime. Higher rates of turning were observed in 4‐day hungry R. marginatus than in 1‐day hungry R. marginatus. Higher rates of turning of R. marginatus were recorded in one S. litura density regime than in four density regimes. One‐day hungry R. marginatus turned 4.14‐fold greater degree mean angle than 4‐day hungry ones. At four S. litura density regime R. marginatus turned 0.34‐fold lesser angle than at one density regime.
Epidemiology of Raspberry Bushy Dwarf Virus in the Czech Republic
Authors: Špak J. , Kubelková D.
Published: March 2003

Extensive monitoring of the raspberry bushy dwarf virus (RBDV) in cultivated raspberry, wild raspberry and blackberry was conducted in 1994‐99. RBDV was revealed by ELISA in 31.6% of field samples, 15.7% plants in germplasm collections and in 43.8% of propagated plants. Infected cultivars were Aborigen, Balzam, Brigantina, Bulharský Rubín, Canby, Comox, F‐103, Findus, Gatineau, Glen Moy, Granát, Heritage, Lloyd George, M‐101, Mája, Meeker, Norfolk Giant, Norna, NS̆‐1D‐101, Skeena, Trent, Veten, ZamatoS̆ and Zeva. The virus was detected in 6.5 and 6.7% of wild raspberry and wild blackberry plants, respectively, at 22.8% and 11.4% of sampled locations. Vegetatively propagated plants seem to be the main source for virus spread in cultivated raspberry, rather than naturally infested wild Rubus populations.
Characteristics of Bacteria from Oilseed Rape in Relation to their Biocontrol Activity against Verticillium dahliae
Authors: Alström S.
Published: March 2003

The potential of bacteria that are adapted to the oilseed rape root environment for use in the biological control of Verticillium dahliae, Kleb was investigated in both controlled and non‐sterile growth conditions. Bacterial strains dominated by the red‐pigmented members of enterobacteriaceae were isolated from thoroughly washed and air‐dried root segments of symptomless young rape plants. Other associated strains found either belonged to Alcaligenes sp., Stenotrophomonas spp. and Pseudomonas spp. (Pseudomonas acidovorans and Pseudomonas putida) or were unidentified according to fatty acid methyl ester profile analysis. A total of 19 strains isolated in this study together with two previously studied strains, Serratia proteamaculans and Pseudomonas chlororaphis, were characterized on the basis of their interactions with V. dahliae and a number of functional characteristics. In line with earlier observations with root‐colonizing fungi also from oilseed rape, all bacterial strains suppressed the pathogen not only directly and but also indirectly in in vitro assays. Mechanisms of suppression were apparently multifold among the strains, but production of hydrogen cyanide does not seem to be involved in indirect inhibition. The majority of the strains possessed the ability to produce cellulases, proteases and phosphatases and some even produced chitinases and induced hypersensitive responses, indicating their potential for nutrient acquisition as well as colonization capacity and active recognition by the plant cells. Investigations in non‐sterile field soil revealed that some strains protected rape plants from V. dahliae partly by delaying symptom development. None of the strains, however, was strongly deleterious to rape growth either in the presence or absence of the pathogen. Light microscopic observations of roots and results based on agar printing techniques revealed the potential of the studied strains to colonize or interfere with the pathogen colonization. This study provides some insight into the evolved relationship of bacterial residents with their host in terms of their potential importance in its fitness.
Variation in Resistance of Camelina (Camelina sativa [L.] Crtz.) to Downy Mildew (Peronospora camelinae Gäum.)
Authors: Vollmann  , Steinkellner  , Glauninger
Published: March 2003

Camelina (Camelina sativa) is a potential oilseed crop for both food and non‐food utilization cultivated on a limited acreage in Europe and North America. An important low‐input feature of camelina is its high level of resistance against plant diseases, which may partly be due to the production of antimicrobially efficient phytoalexins. In Central European countries such as Austria, downy mildew (Peronospora camelinae) is the only disease of camelina which has been found repeatedly, whereas other diseases and pests have been observed only occasionally. Therefore, the genotypic variation of downy mildew incidence was evaluated in two camelina field experiments carried out within a breeding programme. In both experiments, totally resistant breeding lines were identified and a continuous pattern of variation in disease incidence was observed, suggesting a horizontal type of resistance. In bi‐parental populations, disease incidence of progeny appeared to be associated with disease scores of the parent genotypes, and transgressive segregation in disease incidence was also found. In 1998, the rate of downy mildew in camelina was lower than in 1999; in the latter growing season, grain yield was significantly affected by the disease, whereas other agronomic characters remained unaffected.
Potato Leafroll Virus‐assisted Aphid Transmission of Potato Spindle Tuber Viroid to Potato Leafroll Virus‐resistant Potato
Authors: Syller  , Marczewski
Published: March 2003

Potato leafroll virus (PLRV) and potato spindle tuber viroid (PSTVd) are important pathogens affecting the potato (Solanum tuberosum L.). PLRV is transmitted only by aphids, Myzus persicae being its principal vector. In contrast, PSTVd is transmitted by foliar contact and true seeds, but is not aphid‐transmissible. However, in doubly infected plants, PSTVd can be encapsidated by the capsid protein of PLRV and transmitted by M. persicae. In the present experiments, the aphids successfully transmitted PSTVd from potato plants infected with this viroid and PLRV to potato and tomato cv. Rutgers plants. The efficiency of PSTVd transmission depended on the potato cultivar used as inoculum source or as test plant, and ranged from 0 to 55%. Interestingly, PSTVd was the sole pathogen detected in some potato or tomato plants inoculated by aphids fed on the plants infected with the viroid and virus. Sole infections with PSTVd were found in as many as 23% of plants of the potato cv. Irga which is highly resistant to PLRV. This finding indicates that PLRV served as a carrier of PSTVd, but the plants escaped virus infection due to a high level of resistance. The response of potato plants to mixed infections with PSTVd and PLRV was strikingly more severe than those to infection with either pathogen alone. Furthermore, serious disturbances in sprout emergence were indicative of the double infection.