Habitat quality,not habitat amount,drives mammalian habitat use in the Brazilian Pantanal

Landscape Ecology - An understanding of species-habitat relationships is required to assess the impacts of habitat fragmentation and degradation. To date, habitat modeling in fragmented landscapes...     

Crude garlic extract significantly inhibits replication of grapevine viruses

Efforts to control viral diseases of grapevine include the production of certified material and development of virus-resistant transgenic grapevines. However, effective antiviral agents, once the viruses have infected the plants, are still lacking. This study shows that a crude garlic extract has significant antiviral activity against grapevine viruses. Replication of grapevine leafroll-associated virus 2 (GLRaV-2) was obviously inhibited in grapevine cv. Cabernet Sauvignon calli treated with diluted (1:100) garlic extract. The relative RNA levels of GLRaV-2 and grapevine fleck virus (GFkV) in cv. Summer Black grapevine in in vitro-grown plantlets 10 days after treatment with diluted (1:100) garlic extract were about 22% and 20%, respectively, of that in controls. The viral RNA accumulation of GLRaV-2, GFkV, grapevine virus A (GVA), grapevine fanleaf virus (GFLV) and grapevine rupestris stem pitting-associated virus (GRSPaV) in field-grown grapevine cv. Centennial Seedless plants sprayed with diluted (1:100) garlic extract were about 31–40%, 26–38%, 18–31%, 17–42% and 15–18%, respectively, of that in controls. Moreover, the garlic extract treatment led to a significant decrease in viral RNA accumulation of GLRaV-3, GLRaV-2, GVA, GFkV, GFLV, GRSPaV and grapevine Pinot Gris virus in pot-grown grapevine cv. Shine Muscat plants, and viral disease symptoms in these plants were obviously attenuated. In addition, this extract significantly induced expression of pathogenesis-related protein genes and stimulated activity of antioxidant enzymes in grapevines. Taken together, these results indicate that the crude garlic extract acts as a significant inhibitor against a broad range of grapevine viruses.     

Mycobacterium fortuitum abortion in a sow

Two aborted Chester White pig fetuses were presented to a veterinary diagnostic laboratory in Illinois. Postmortem examination identified no gross abnormalities. Histologic evaluation revealed multifocal necrosis of chorionic epithelial cells, coalescing areas of mineralization in the placenta, and focal accumulations of viable and degenerate neutrophils in the lung. Intra- and extracellular acid-fast bacilli were identified in the lesions in both the placenta and lungs. Bacterial culture of stomach contents yielded heavy growth of Mycobacterium fortuitum, a rapidly growing nontuberculous mycobacterium (NTM), which was further confirmed through whole-genome sequencing. NTM are opportunistic pathogens commonly found in the soil and in contaminated water supplies. In animals, M. fortuitum is typically introduced through cutaneous wounds leading to infections limited to the skin, with systemic infection being uncommon. To our knowledge, abortion caused by M. fortuitum has not been reported previously.     

Food animals as reservoirs and potential sources of multidrug-resistant diarrheagenic E. coli pathotypes: Focus on intensive pig farming in South Africa

BackgroundDiarrheagenic E. coli (DEC) strains are a major cause of diarrheal diseases in both developed and developing countries. Healthy asymptomatic animals may be reservoirs of zoonotic DEC, which may enter the food chain via the weak points in hygiene practices.AimWe investigated the prevalence of DEC along the pig production continuum from farm-to-fork.MethodsA total of 417 samples were collected from specific points along the pig production system, that is, farm, transport, abattoir and food. E. coli was isolated and enumerated using Colilert. Ten isolates from each Quanti-tray were selected randomly and phenotypically identified using eosin methylene blue agar selective media. Real-time polymerase chain reaction (PCR) was used to confirm the species and to classify them into the various diarrheagenic pathotypes. Antimicrobial susceptibility was determined against a panel of 20 antibiotics using the Kirby-Bauer disk diffusion method and EUCAST guideline.ResultsThe final sample size consisted of 1044 isolates, of which 45.40% (474/1044) were DEC and 73% (762/1044) were multidrug-resistant. Enteroinvasive E. coli (EIEC) was the most predominant DEC at all the sampling sites.ConclusionThe presence of DEC in food animal production environments and food of animal origin could serve as reservoirs for transmitting these bacteria to humans, especially in occupationally exposed workers and via food. Adherence to good hygienic practices along the pig production continuum is essential for mitigating the risk of transmission and infection, and ensuring food safety.     

Buyer beware! Disease testing newly arrived cattle to dairy farms in Ontario

The objective of this cross-sectional study was to evaluate the presence of infectious disease in newly arrived cattle on dairy farms in Ontario. Cattle that were more than 2 years old and arrived at dairy farms within the previous year were tested. A total 321 cattle from 56 dairy farms were sampled and had blood submitted to a diagnostic laboratory. Of all sampled cattle, 0.0%, 39.6%, 2.2%, and 1.3% tested positive for Anaplasma, bovine leukemia virus, Mycobacterium avium subsp. paratuberculosis, and Salmonella Dublin, respectively. Based on these results, it is imperative that dairy producers are vigilant to ensure they do not purchase animals with these important and untreatable infectious diseases.     

Meta-analysis of fungicide efficacy on soybean target spot and cost–benefit assessment

Target spot of soybean has spread in Brazil, the southeastern United States and Argentina in the last decade. A collaborative network of field Uniform Fungicide Trials (UFT) in Brazil was created in 2011 to study the target spot control efficacy of fungicides, including azoxystrobin + benzovindiflupyr (AZ_BF), carbendazim (CZM), fluxapyroxad + pyraclostrobin (FLUX_PYRA), epoxiconazole + FLUX_PYRA (EPO_FLUX_PYRA), mancozeb (MZB) and prothioconazole + trifloxystrobin (PROT_TRIF). Network meta-analysis was used to conduct a quantitative synthesis of UFT data collected from 2012 to 2016 and to evaluate the effects of disease pressure (DP, low ≤ 35% target spot severity in the nontreated control < high) and year of experiment on the overall mean efficacy and yield response to each of the tested fungicides. Based on mean percentage control of target spot severity, the tested fungicides fall into three efficacy groups (EG): high EG, FLUX_PYRA (76.2% control relative to the nontreated control) and EPO_FLUX_PYRA (75.7% control); intermediate EG, PROT_TRIF (66.5% control) and low EG, MZB (49.6% control), AZ_BF (46.7% control) and CZM (32.4% control). DP had a significant effect on yield response. At DP_Low, the highest response was due to PROT_TRIF (+342 kg ha⁻¹, +12.8%) and EPO_FLUX_PYRA (+295.5 kg ha⁻¹, +11.2%), whereas at DP_High, EPO_FLUX_PYRA and FLUX_PYRA outperformed the other treatments, with yield responses of 503 kg ha⁻¹ (+20.2%) and 469 kg ha⁻¹ (+19.1%), respectively. The probability of a positive return on fungicide investment ranged from 0.26 to 0.56 at DP_Low and from 0.34 to 0.66 at DP_High.     

Spatial patterns of the Citrus leprosis virus and its associated mite vector in systems without intervention

Leprosis is caused by the Citrus leprosis virus cytoplasmic type and is vectored by the mite Brevipalpus yothersi. Miticide applications, which cost $54 million annually, are based on inspection for the presence of mites. The aim of the present study was to characterize the spatial patterns of B. yothersi-infested trees and trees with leprosis symptoms for further improvement in sampling and disease control. The presence of mites and the occurrence of leprosis were assessed over two years in 1160 Valencia trees and 720 Natal trees in a commercial sweet orange grove in Sao Paulo State, Brazil. To assess the natural growth and dispersal of mites and leprosis, mite populations were not controlled during the experimental period. Maps of mite-infested trees and trees with leprosis symptoms were analysed at three different levels of spatial hierarchy using complementary methods, i.e. among adjacent trees within and across rows, within quadrats, and the strength and orientation of aggregation among quadrats. The study showed that the spatial patterns of virus-infected and mite-infested trees were different, with a strong aggregation pattern of trees with leprosis symptoms that increased over time. Conversely, the spatial pattern of B. yothersi showed randomness or weak aggregation at all three spatial hierarchical levels. Disease incidence increased steadily in plots of both cultivars, unlike in mite-infested trees where incidence fluctuated over time. These results have important implications for the development of better management strategies for leprosis. Sampling methods and action thresholds for mite control should consider primary disease inoculum in addition to the incidence of mites.     

Distribution and genetic diversity among Aspergillus flavus isolates across three agro-ecologies essential for maize cultivation in Ghana

Fungal mycotoxins are important contaminants of agricultural commodities that pose serious concerns to producers, consumers and exporters. Aflatoxin is a carcinogenic metabolite produced by the fungi Aspergillus flavus and A. parasiticus. These fungi and other mould species living in the soil contaminate several crops including maize. This study was undertaken with the following objectives: (i) to assess the presence of A. flavus and other moulds in Ghanaian soil; (ii) to determine the distribution and density of A. flavus under three agro-ecologies noted for major maize production; and (iii) to assess the effect of percentage of carbon (C) and nitrogen (N) and soil pH on A. flavus population densities and diversity in the isolates found across the agro-ecologies. The data showed seven moulds that were common across the agro-ecologies. Significant differences (P < 0.05) were observed in the A. flavus density and distribution within and across these agro-ecologies. Fumesua soils recorded the highest levels of A. flavus (1.185 × 10³ cfu g⁻¹) while Akomadan recorded the least (9.76 × 10² cfu g⁻¹). Percentage available C, N and soil pH did not significantly influence A. flavus density. The A. flavus isolates identified in this study varied in genetic sequence within the aflatoxin gene cluster, but these differences were not distinguishable by origin.