Die KartoffelnematodenGlobodera rostochienis (woll.) Behrens undG. pallida (Stone) Behrens und ihre Pathotypen in Schweden

Zusammenfassung 44–66% der 5973 untersuchten Kartoffelfl?chen waren mit Kartoffelnematoden befallen. Durch den zunehmenden Einsatz von resistenten Sorten konnte die Befallsdichte vor allem in den südlichen Fabrikkartoffelanbaugebieten reduziert werden. Eine Kombination des Pathotypentests mit morphologischen Untersuchungen der Spicula der M?nnchen verkürzt den Zeitaufwand für die Pathotypenbestimmung. Die 366 getesteten Herkünfte waren Mischpopulationen, in denen Ro 1 dominierte. Ro 4 trat in 8 F?llen (2%) auf. 13% der Nematodenpopulationen enthielten resistenzbrechende Pathotypen, davon 6%G. pallida. Ro 5 kam bisher nur in einer Population gemeinsam mit Pa 3 vor. 16 neue resistente Sorten wurden mit Nematodenherkünften aus Südschweden geprüft. Eine obligatorische Bodenprobenentnahme und der Anbau von Sorten mit unterschiedlicher Nematodenresistenz im Wechsel mit weniger anf?lligen Sorten wird als Bek?mpfungsmassnahme empfohlen.

---

Summary The main potato growing areas in Sweden for starch and table potatoes are in the southern provinces (Schonen, Blekinge, Halland, ?sterg?tland). As a result it is here that the highest levels of soil infestation by potato cyst nematodes are found. Of 5973 potato fields of different sizes examined between 1979 and 1984, 44–66% were infested with potato cyst nematodes (Table 1). The increasing use of resistant cultivars (in 1983, 60% of the starch and 4% of the table cultivars were resistant) has reduced infestations, particularly in the southern potato growing areas. Pathotype tests on 366 nematode populations from fields where resistant cultivars have been grown frequently, revealed that the cyst nematodes occurred in mixed populations, in whichGlobodera rostochiensis (Woll.) Behrens, Ro 1, dominated. Ro 4 could be detected in 8 cases (2%). This pathotype seems to occur much more frequently in Swedish populations but may not be recognized as long asS. andigena-resistant cultivars are grown. Thirteen percent of the nematode populations contained resistance-breaking pathotypes (i.e. other than Ro 1 and Ro 4), with 6%Globodera pallida (Stone) Behrens. TheG. pallida fraction, with the exception of the population SK1/80, is as yet minor, as can be seen from Tables 2 and 3. Ro 5 only occurred in one population together with Pa 3. Sixteen resistant starch cultivars from the Netherlands, Denmark and the Federal Republic of Germany were tested against six isolated nematode populations (3 pure pathotypes—Ro 2, Ro 5, Pa 3; 3 pathotype mixtures—Ro 3/4, Pa). All the cultivars, with the exception of Danva and Fecuva, depressed the multiplication rates of the pathotype mixtures (Table 3). Cultivars which contained onlyS. vernei and noS. andigena (Danva, Fecuva) increased the multiplication rates of pathotype mixtures with a high proportion of Ro 4. No cultivar was resistant to virulence group Pa 3. Only Elles, Senator and Atrela proved to be less susceptible to Pa 3. Such cultivars with lower multiplication rates could be of practical value in the absence of resistant cultivars. Obligatory soil sampling and rotations of cultivars with different nematode resistances with fewer susceptible cultivars, is recommended as a control strategy.

---

Résumé Les principales régions de production de pommes de terre destinées à la féculerie et à la consommation se situent dans les provinces du sud de la Suède (Schonen, Blekinge, Halland, ?sterg?tland). Par conséquent, c'est dans ces régions que l'on trouve le plus de sols contaminés de nématodes (fig. 1). Sur les 5973 champs de surfaces inégales, contr?lés entre 1979 et 1984, 44–66% étaient contaminés avec les nématodes (fig. 1). Par l'utilisation croissante de variétés résistantes (en 1983, le 60% des variétés destinées à la féculerie et le 4% des variétés de consommation étaient résistantes), le taux de contamination a pu être réduit, particulièrement dans les régions du sud destinées à la production de pommes de terre industrielles. Des tests de pathotypes effectués avec 366 provenances de nématodes, prélevés dans les champs régulièrement cultivés avec des variétés résistantes, ont démontré qu'il s'agissait avant tout de populations mixtes avec une dominance deGlobodera rostochiensis (Woll.) Behrens, Ro 1. La race Ro 4 a été isolée dans 8 cas (2%). Il faut admettre que ce pathotype est probablement bien plus répandu en Suède, mais il n'appara?t pas avec la culture des variétés résistantes auS. andigena. 13% des populations de nématodes contenaient des pathotypes capables de supprimer cette résistance, c'est-à-dire autres que Ro 1 et Ro 4, dont 6% deGlobodera pallida (Stone) Behrens. Comme on peut le lire sur le tableau 2 et 3, la proportion deG. pallida dans les mélanges de pathotypes est encore assez faible, à l'exception de la population SK1/80. La race Ro 5 n'a été trouvée que dans une seule provenance en association avec Pa 3. 16 variétés de pommes de terre riches en amidon et reconnues résistantes, en provenance des Pays-Bas, du Danemark, de la RFA ainsi que 2 variétés de la RDA ont été testées avec 6 populations de nématodes isolées au sud de la Suède: 3 pathotypes purs (Ro 2, Ro 5 et Pa 3) et 3 mélanges de pathotypes (Ro 3/4, Pa). A l'exception de Danva et Fecuva, ces variétés ont eu une bonne efficacité dans l'assainissement des mélanges de pathotypes (tab. 3). Les variétés qui contiennent uniquementS. vernei (et pas deS. andigena) soit Danva et Fecuva, augmentèrent le taux de reproduction des mélanges de pathotypes avec une forte proportion de Ro 4. Aucune variété n'était résistante au groupe Pa 3. Seules les variétés Elles, Senator et Atrela semblèrent moins sensibles à Pa 3. Par leur effet limitatif sur la reproduction de ce pathotype, de telles variétés pourraient présenter une certaine importance pratique en l'absence d'obtentions résistantes à Pa 3. Dans la stratégie de lutte, il est recommandé d'instaurer un contr?le obligatoire d'échantillons de terre et de cultiver des variétés présentant différentes résistances aux nématodes, en alternance avec des variétés moins sensibles.

     

Flavonoids in baby spinach (Spinacia oleracea L.): changes during plant growth and storage

The variation in flavonoid concentration and composition was investigated in baby spinach (Spinacia oleracea L.) cv. Emilia sown on three occasions, each harvested at three growth stages at 6-day intervals. After harvest, leaves were stored in polypropylene bags at 2 or 10 degrees C. Flavonoids were analyzed by reversed phase HPLC. Twelve flavonoid peaks were detected. The main flavonoid, making up on average 43% of the total flavonoid concentration, was identified as 5,3',4'-trihydroxy-3-methoxy-6:7-methylenedioxyflavone-4'-glucuronide. Four other flavonoids each contributed 7-12% of the total flavonoid content. Total flavonoid content was relatively stable during normal retail storage conditions, although some of the individual flavonoid compounds showed considerable variation. The youngest plants had the highest flavonoid concentration, indicating that by harvesting the baby spinach a few days earlier than the current commercial stage of harvest, the flavonoid concentration in the product may be increased and the content of potentially health-promoting compounds enhanced.     

Delayed harvest of reed canary grass translocates more nutrients in rhizomes

Abstract

Two field experiments, one in large plots and the other in small framed plots, were conducted in Umeå, northern Sweden. The objectives were (1) to examine the seasonal patterns of rhizome growth and nutrient dynamics of the energy crop reed canary grass (Phalaris arundinacea L.) in ley I and II, and (2) to evaluate the roles of soil type (mineral vs. organic), fertilisation level (0, 50, and 100 kg N ha^?1s), and season/harvest time (Oct-96, May-97, and Aug-97) on the rhizome growth and nutrient dynamics by means of a factorially designed experiment. The general pattern of rhizome growth was that biomass was low in June during initiation of shoot growth, but increased steadily during the growing season, reached a peak in late autumn, and remained high until next spring. The N and P accumulation in rhizomes followed a similar pattern. During ley years I and II, reed canary grass rhizome growth was less dependent on soil type, and more dependent on fertilisation and season, with fertilisation being the most important predictor of growth. The season/harvest time, followed by soil type, was the most important factor for both concentrations and therefore total uptake of N, P, and K in rhizomes. Soil type affected N content in rhizomes significantly, and also interacted with season and enhanced the effect on N, P, and K content in rhizomes. The seasonal dynamics of the nutrient content in rhizomes indicate a remobilisation of the nutrients from rhizomes to the regrowth of shoots and roots in spring and relocation/storage from aboveground shoots to rhizomes during late summer and autumn. The results of this study suggest that delaying the harvest to later than October would result in considerably more energy and nutrient resources being translocated from aboveground shoots to rhizomes for growth in the next season.     

Animal- and herd-level risk factors for leptospiral seropositivity among sows in the Mekong delta, Vietnam

In 1998, a total of 424 sows had sera collected in the Mekong delta in Vietnam. Of these, 283 sows were from 151 small-scale family farms in 19 villages, and 141 from seven large-scale state farms. The sera were subjected to the microscopic agglutination test (MAT) for antibodies to 13 Leptospira serovars. The overall leptospiral seroprevalence for titres > or =1:100 and > or =1:400, was 73 and 29%, respectively, and was higher (P=0.001) at small- than at large-scale farms. The highest seroprevalence was recorded for Leptospira interrogans serovar (sv) bratislava (52%). At small-scale farms, higher prevalences were found to serovars L. interrogans sv icterohaemorrhagiae (P=0.04) and L. interrogans sv pomona (P=0.02).Epidemiological information (at the individual-animal and herd-levels) was collected with a questionnaire. The data were analysed using logistic multiple regression. At the animal-level, sows seropositive for L. interrogans sv australis and sv autumnalis had less direct contact with sows in neighbouring pens (odds ratio (OR)=0.3 and 0.4, respectively) and sows seronegative for L. interrogans sv bratislava were of lower age (OR=0.1 for seropositivity). Also, sows seropositive for L. interrogans sv icterohaemorrhagiae had higher odds (OR=5.8) if they had not been born on the farm (had been introduced to it as gilts).Herds seropositive for sv javanica showed association with farms not taking measures to control the local rodent population (OR=7.8). Serovar pomona was also linked to the use of artificial insemination (AI), as opposed to natural-breeding services (OR=11.2).These results indicate that housing and management could affect the seroprevalence of Leptospira infection in pigs.     

Grazing by Steers at Different Sward Surface Heights on Extensive Pastures: A Study of Weight Gain and Fat Deposition

Live weight gain of steers grazing at three different target sward heights, Low (3-6 cm), Medium (6-10 cm) and High (>10 cm), together with carcass fat deposition, were studied during two grazing seasons. Sward height was measured with a sward stick. The grassland consisted of seminatural grazing areas mixed with previously cultivated areas. Animals grazed continuously with small adjustments in animal numbers (year 1) or pasture area (year 2) to maintain sward height within the target for each treatment. The recorded average sward heights were 4.7, 6.8 and 11.1 cm for pastures on treatments Low, Medium and High, respectively. The animals weighed approximately 440 kg at the start of the grazing season and went directly from pasture to slaughter at the end of the experiment. No differences between years were found and data from both years were thus pooled, giving a total of 50 steers of the Swedish Red and White breed in the data set. Over the whole grazing season, the average daily live weight gain of animals on treatment Low (0.43 kg day     

Performance,health and behaviour of organic growing-finishing pigs in two different housing systems with or without access to pasture

Abstract

The effects of two housing systems (deep litter and straw-flow), with and without access to pasture during the summer period, were studied in an organic growing-finishing pig herd. Performance, health, skin lesions and daytime pig activity were studied in 29 pens of 16 pigs (total of 464 pigs, in 4 batches). Data from 21 pens were used for comparisons of deep litter and straw-flow and data from 16 pens for comparisons of access/no access to pasture. Pigs in the deep litter system had a lower carcass meat percentage (56.6% vs. 57.3%) and more locomotion problems (4.4% vs. 0%) than pigs in the straw-flow system. No difference in daytime pig activity was detected between the two housing systems. Under moderate temperatures, pigs with access to pasture and fed a commercial organic feed inside the building were not more active during daytime behaviour studies (7.30?h–16.30?h) than pigs without access to pasture. However, at 17 weeks of age the pigs with pasture access spent 21% of their time on pasture, less time inside the pig house (20% vs. 33%) and less time on the outside concrete area (4% vs. 12%) than the pigs without pasture. No difference in performance was detected between pigs with and pigs without access to pasture.     

Pup mortality in laboratory mice – infanticide or not?

Background

Despite being the most commonly used mammal in biomedical research, problems with perinatal mortality in mice have received little attention and the causes of pup death are still poorly known. Females are often housed alone with their litters and since the lost pups are generally eaten, it is commonly assumed that the mother has killed them. However, more detailed observations than have been reported previously in the literature are required to establish if the cause of death is infanticide. Litter loss can only be prevented efficiently after underlying causes have been carefully investigated and interpreted. The aim of this study was to investigate if females actively kill their pups by observing the behaviour of females and pups in litters that later were lost. We used video recordings of females that lost their entire litter to observe females in detail from parturition until the pups died. In total, 10 C57BL/6 females (wildtype and the knockouts Hfe^−/− and β2m^−/−) were studied, housed in Makrolon II cages with or without access to a small amount of nesting material.

Results

Three of the females had pups that were never seen moving, and another three females had one or two pups that never moved, indicating that some pups were most likely still-born. In five females with live-born pups, detailed observations from the time when a pup was last seen moving until it died were possible to carry out. We observed females eating dead offspring and interacting with both moving and dead pups. However, we never observed a pup stop moving when manipulated by the female, nor were any wounds seen in the pups. Hence, we found no evidence of infanticide when studying females that had lost their entire litter.

Conclusion

These results suggest that other causes than infanticide plays a major role in mouse pup death, and stress the need for more systematic and careful investigations of the causality of litter loss.     

Patterns of genetic structuring in the coral Pocillopora damicornis on reefs in East Africa

Background  

Studies of population genetic structures provide an indication of direction and magnitude of larval transport and hence are an important component in the assessment of the ability of reefs to recover from severe disturbance. This paper reports data on population genetic structures in the coral Pocillopora damicornis from 26 reefs in Kenya and Tanzania.     

Confirmation of a Campylobacteriosis Outbreak Associated with Chicken Liver Pâté Using PFGE and WGS

In May 2012, an outbreak of campylobacteriosis occurred in southern Sweden at a wedding reception affecting 44 persons. A total of 17 cases were notified (13 were culture positive for Campylobacter spp.). Epidemiological investigation suspected chicken liver pâté as the source of infection. The liver pâté had been deliberately undercooked, lightly fried to keep the right texture and mixed with spices. Campylobacter isolates from six cases as well as three Campylobacter isolates from chicken flocks previously raised by the producer delivering the liver were subtyped using pulsed‐field gel electrophoresis and whole‐genome sequencing. Indistinguishable PFGE profiles were identified among five human and one chicken C. jejuni isolates as well among the two C. coli isolates, one from a human case and one from a chicken. WGS supported the PFGE findings; the six C. jejuni isolates belonged to one cluster. All these six isolates were of MLST type ST 50 (ST‐CC 21). This study highlights the importance of a combination of strict biosecurity at the flock‐level as well as adequate cooking of chicken liver to prevent transmission of Campylobacter to humans.