Status of black grass (Alopecurus myosuroides) resistance to acetyl-coenzyme A carboxylase inhibitors in France

We assessed the contributions of target site‐ and non‐target site‐based resistance to herbicides inhibiting acetyl‐coenzyme A carboxylase (ACC) in Alopecurus myosuroides (black grass). A total of 243 A. myosuroides populations collected across France were analysed using herbicide sensitivity bioassay (24 300 seedlings analysed) and ACC genotyping (13 188 seedlings analysed). Seedlings resistant to at least one ACC‐inhibiting herbicide were detected in 99.2% of the populations. Mutant, resistant ACC allele(s) were detected in 56.8% of the populations. Among the five resistant ACC alleles known in A. myosuroides, alleles containing an isoleucine‐to‐leucine substitution at codon 1781 were predominant (59.5% of the plants containing resistant ACC alleles). Comparison of the results from herbicide sensitivity bioassays with genotyping indicated that more than 75% of the plants resistant to ACC‐inhibiting herbicides in France would be resistant via increased herbicide metabolism. Analysis of herbicide application records suggested that in 15.9% of the populations studied, metabolism‐based resistance to ACC‐inhibiting herbicides was mostly selected for by herbicides with other modes of action. Our study revealed the importance of non‐target site‐based resistance in A. myosuroides. Using herbicides with alternative modes of action to control populations resistant to ACC‐inhibiting herbicides, the recommended management approach, may thus be jeopardised by the widespread occurrence of metabolism‐based resistance mechanisms conferring broad‐spectrum cross‐resistance.     

The face of conservation responding to a dynamically changing world

In its 40‐year history, the science of conservation has faced unprecedented challenges in terms of environmental damage and rapid global change, and environmental problems are only increasing as greater demands are placed on limited natural resources. Conservation science has been adapting to keep pace with these changes. Here, we highlight contemporary and emerging trends and innovations in conservation science that we believe represent the most effective responses to biodiversity threats. We focus on specific areas where conservation science has had to adjust its approach to address emerging threats to biodiversity, including habitat destruction and degradation, climate change, declining populations and invasive species. We also document changes in attitudes, norms and practices among conservation scientists. A key component to success is engaging and maintaining public support for conservation, which can be facilitated through the use of technology. These recent trends in conservation and management are innovative and will assist in optimizing conservation strategies, increasing our leverage with the general public and tackling our current environmental challenges.     

CAN SONOGRAPHIC FINDINGS PREDICT THE RESULTS OF LIVER ASPIRATES IN DOGS WITH SUSPECTED LIVER DISEASE?

While abdominal ultrasound and ultrasound-guided fine-needle aspiration cytology are often combined to help determine the type of liver disease in dogs, little is known about the relationship that may exist between the results of these tests. We hypothesized that specific sonographic findings, or combinations of findings, may predict results of liver ultrasound-guided fine-needle aspiration cytology. Hepatic and extrahepatic sonographic findings were recorded prospectively using a standardized form in 70 dogs with clinically suspected liver disease and in which liver ultrasound-guided fine-needle aspiration cytology was performed. The predictive value of sonographic findings in regard to the category of cytology results was assessed with stepwise logistic regression analysis. Sonographic detection of a hepatic mass (≥3 cm; risk ratio [RR] 3.83, 95% Wald confidence intervals [95% CI] 2.42–3.93, P =0.0036), ascites (RR 3.82, 95% CI 1.94–4.28, P =0.0044), abnormal hepatic lymph node(s) (RR 3.01, 95% CI 1.22–4.88, P =0.0262), and abnormal spleen (RR 3.26, 95% CI 1.20–3.85, P =0.0274) were the most predictive of liver neoplasia on cytology. Conversely, sonographic detection of hepatic nodules (<3 cm; RR 1.97, 95% CI 0.95–2.96, P =0.0666) was most predictive of vacuolar hepatopathy on cytology. In dogs with suspected liver disease, several sonographic findings, alone or combined, are thus predictive of liver ultrasound-guided fine-needle aspiration cytology results. In the light of the fact that ultrasound-guided fine-needle aspiration cytology of the liver has limitations, these predictabilities could influence the selection of diagnostic tests to reach a reliable diagnosis.     

Effects of intercropping and soil amendment with urea and calcium oxide on the incidence of bacterial wilt of tomato and survival of soil-borne Pseudomonas solanacearum in Taiwan

Intercropping and soil amendment experiments were conducted to determine if they reduced populations of Pseudomonas solanacearum and bacterial wilt of tomato at the Asian Vegetable Research and Development Center (AVRDC) and at three other locations in Taiwan. At AVRDC, intercropping tomato with cowpea planted within the row significantly reduced bacterial wilt ( P  < 0.05) compared to when tomato was cropped alone. The P. solanacearum population in soil was not affected by intercropping with cowpea, soybean, or Welsh onion. At the same site, however, a preplanting soil amendment consisting of urea (200 kg ha⁻¹ N) and CaO (5000 kg ha⁻¹) significantly reduced the pathogen population and tomato bacterial wilt ( P  < 0.001). The effect of the soil amendment was not consistent when applied to soil from three other sites in Taiwan; in soil from two sites no reduction of the pathogen population occurred. At these sites, tomato bacterial wilt in the field was not reduced significantly after amending. In comparison with a non-amended control, the addition of only CaO reduced the P. solanacearum population in AVRDC soil significantly ( P  < 0.05), but the reduction was significantly greater when the complete soil amendment was added. In contrast, urea alone did not affect the survival of P. solanacearum in the soil. In a greenhouse experiment with AVRDC soil, P. solanacearum was undetectable 2 weeks after soil amendment, but in the same treatment tomato yield was significantly reduced by 48% ( P  < 0.05) compared with non-amended treatments. The suppressive effect of the soil amendment on the P. solanacearum population was probably due to the generation of one or several toxic substances during the transformation of urea in the presence of CaO.     

除草剂污染堆肥用量对番茄生长的影响

为降低有机肥料使用过程中痕量除草剂对农业安全生产的风险,采用市售基质、普通堆肥和受除草剂污染的堆肥为试材,设置4个处理(无污染堆肥、二氯吡啶酸污染堆肥、氟乐灵污染堆肥和环丙嘧啶酸污染堆肥),在0、5%、10%和20%不同堆肥用量条件下,以番茄的出苗率和播种后45d时植株的株高、叶片面积、茎粗、植株干质量、根长和壮苗指数为评价指标判断除草剂污染堆肥对番茄种子萌发及植株生长的影响。结果表明,除草剂污染堆肥对番茄种子的萌发及生长都有一定的抑制作用,随污染堆肥用量的增加抑制作用增加,且对作物产物抑制作用的污染堆肥用量及抑制作用大小因除草剂种类而异,二氯吡啶酸污染堆肥对番茄生长的影响最大。植物生长指标茎粗、植物干质量和根长较株高和叶面积而言,对除草剂污染更敏感。     

Carrier state in furunculosis: secondary infection of trout with different Aeromonas salmonicida strains results in advantage for the primarily harboured one

Abstract. On the basis of previous observations, in vivo experiments were conducted in rainbow trout, Oncorhynchus mykiss (Walbaum), to detect possible competition between strains of Aeromonas salmonicida differing in their pattern of resistance to antimicrobial drugs. Serial infections, or reinfection of naturally-infected trout, were induced by intramuscular injection. Surviving fish were artificially stressed, and all dying fish were examined using selective media to assess the type of latent infection. Secondary infections with virulent strains always resulted in mortality and reisolation of the secondary strain in pure culture. However, when trout having undergone the two successive infections were stressed, the primary strain was always reisolated. Primary strains seem to be able to survive in unknown locations within cells or tissues, regardless of their virulence or growth potency. Although a protective effect conferred by latent infection to secondary challenge could not be clearly proven, such mechanisms resemble what occurs in premunition and could be of epidemiological interest.