Biological control of pigweeds (Amaranthus retroflexus, L. A. Powellii, S. Watson and A. bouchonii Thell.) with phytophagous insects, fungal pathogens and crop management

Pigweeds (Amaranthus spp.) are of economic importance worldwide. In Europe, Amaranthus retroflexus is one of the ten weed species of greatest economic importance. It is a serious problem weed in several field crops (e.g. maize), as well as in vegetables, orchards and grape vines. It is an annual spreading by seeds which have a long viabilityand are dispersed principally by wind and water, but also by machinery. There is great variability in seed germination which renders control with post-emergence herbicides difficult. In addition, triazine herbicide-resistant populations occur in ten European countries. The aim of this subproject of COST action 816 is to investigate the possibilities of classical and inundative biological control of Amaranthus spp., to characterize potentialbiological control agents and to develop methods for their integration with current phytosanitary measures in the target crops. The project was initiated with an extended literaturesurvey followed by field surveys for insects and pathogens associated with Amaranthus spp. in several European countries. Promising isolates of fungal pathogens have been tested ondetached leaves and whole plants, and initial studies on the application of pathogens causing damping off in seedlings have been made. Further, the variability of different provenances ofAmaranthus spp. in response to fungal attack has been investigated     

Allelopathy in the rhizosphere and amended soil of Chenopodium murale L.

Soil infested with Chenopodium murale and amended with it were investigated to verify their allelopathic effects on seedling emergence and some growth and physiological parameters of five test species, Trifolium alexandrinum, Triticum aestivum, Melilotus indicus, lycopersicum esculentum and Cucumus sativus. The two types of soil exhibited phytotoxic effects on the seedling emergence of the test species. Growth and physiological parameters were significantly inhibited when the soil was amended with a high concentration of C. murale tissues. Soil amended with shoot tissue had more inhibitory effects than soil amended with root tissue, at the same concentration. M. indicus was more inhibited than the other species in relation to leaf area, dry matter, pigment, carbohydrates and protein contents.     

Observations and treatment of Nitzschia sturionis on Atlantic sturgeon from Chesapeake Bay

From 2004 to 2008, 10% of Atlantic sturgeon Acipenser oxyrinchus oxyrinchus examined during a bycatch study of Maryland's Chesapeake Bay were infested with the trematode Nitzschia sturionis on the skin and gills. The parasite intensity increased on 75% of infested fish 4-24 months after being placed in captivity. Mean parasite intensity increased to a greater extent on the skin (up to 100-fold) than on the gills (up to 16-fold). Atlantic sturgeon that were infested with N. sturionis gained weight at a reduced rate or lost weight compared with uninfested fish. Skin lesions associated with N. sturionis progressed from a few reddened foci to hemorrhagic ulcers and depigmentation, while gill lesions showed a less-dramatic progression. Host tissues identified in the intestinal ceca of N. sturionis consisted primarily of malpighian cells, but small amounts of blood were also found in worms attached to lesions in the skin and gills. An Atlantic sturgeon infested with approximately 500 worms was successfully treated with a 3-h bath of praziquantel at 10 mg/L. This first report of N. sturionis from Chesapeake Bay extends the parasite's reported southern range in North America.     

Effects of the aqueous extracts of Zygophyllum fabago on the growth of Fusarium oxyosporum f. sp. melonis and Pythium aphanidermatum

In this study, the effects of aqueous extracts from Zygophyllum fabago L. on two plant phytopathogenic fungal species (namely, Fusarium oxyosporum f. sp. melonis and Pythium aphanidermatum) were studied under laboratory conditions. The plant extracts (10% w/v) were prepared by using deionized water and fresh tissues. Dilutions (2, 4, 6, and 8% w/v) were obtained to test their effect on the mycelial growth of the phytopathogenic species. Additionally, the recovery of the fungi after their exposure to the Z. fabago extract was analyzed. The plant extracts inhibited the growth of F. oxyosporum and P. aphanidermatum (the maximum mean inhibition that was recorded with the 10% w/v extracts was 42.9% and 85.3%, respectively). A second series of experiments demonstrated the existence of residual effects in both species. The amount of residual inhibition by the 10% w/v extracts was 28.6% in F. oxyosporum and 53.8% in P. aphanidermatum. A dose–response was clearly observed in P. aphanidermatum, while an increase in extract concentration was not associated with a significantly greater reduction in the growth of F. oxyosporum. These findings give insights into the potential of Z. fabago as a growth inhibitor of F. oxyosporum and P. aphanidermatum, thus suggesting an interesting potential role for this common weed as a source of natural fungicides.     

Calf and colostrum management practices on New Zealand dairy farms and their associations with concentrations of total protein in calf serum

AIMS: To gather information on management practices and farmer attitudes to management of cows and calves during the immediate post-partum period on dairy farms in New Zealand, and to assess these practices for associations with concentrations of total protein (TP) in serum of calves 1–8 days-old.

METHOD: Between July and September 2015 blood samples were collected from calves aged between 24 hours and 7 days, from dairy farms (n=105) in nine areas in New Zealand, on three occasions throughout the calving period. Concentrations of TP were determined in all serum samples. At each visit technicians collected 1?L of the pooled colostrum that was intended for feeding to newborn calves that day. These samples were assessed for Brix, coliform and total bacterial counts. After the last sampling visit, the calf rearer or farm manager were asked to complete a questionnaire describing calf and colostrum management practices on the farm. Potential farm-level variables associated with concentrations of TP in serum of sampled calves were identified using univariable and multivariable linear mixed models.

RESULTS: Mean concentration of TP in serum of calves across all farms was 59.8 (95% CI=59.4–60.2) g/L, and was associated with region and herd size in the final multivariable model. Concentrations of TP were lower in calves from farms in Otago (56.2 (95% CI=53.4–58.9) g/L) and Southland (56.9 (95% CI=54.1–59.7) g/L) compared to calves on farms in the Far North (62.6 (95% CI=59.8–65.3) g/L), and were lower in calves from farms with a herd size >600 (58.3 (95% CI=56.7–59.8) g/L) than ≤600 (61.3 (95% CI=60.1–62.5) g/L) cows. After accounting for fixed effects, farm accounted for only 8.4% of the unexplained variation. There was no association between any of the measures of colostrum quality and concentrations of TP in serum (p>0.2).

CONCLUSION AND CLINICAL RELEVANCE: Very few herd-level variables were associated with concentrations of TP in serum. Risk factors that have been shown to be of importance in previous studies outside New Zealand were not identified as important in the current study. It is possible that, in the situation where calves are kept at pasture with their dams for prolonged periods, variables which influence how well a cow can feed its calf in the first 12–24 hours have a larger influence on concentrations of TP in serum than the collection and management of calves once they reach the rearing shed.     

Spatial Response of Mammals to Late Quaternary Environmental Fluctuations

Analyses of fossil mammal faunas from 2945 localities in the United States demonstrate that the geographic ranges of individual species shifted at different times, in different directions, and at different rates in response to late Quaternary environmental fluctuations. The geographic pattern of faunal provinces was similar for the late Pleistocene and late Holocene, but differing environmental gradients resulted in dissimilar species composition for these biogeographic regions. Modern community patterns emerged only in the last few thousand years, and many late Pleistocene communities do not have modern analogs. Faunal heterogeneity was greater in the late Pleistocene.