<Emphasis Type="Italic">RB</Emphasis> and <Emphasis Type="Italic">Ph</Emphasis> resistance genes in potato and tomato minimize risk for oospore production in the presence of mating pairs of <Emphasis Type="Italic">Phytophthora infestans</Emphasis>

Composed mostly of fungivorous species, the genus Aphelenchoides also comprises 14 plant-parasitic species. The most common and devastating, A. besseyi, A. fragariae, A. ritzemabosi and A. subtenuis have been reported on more than 900 plant species. The combination of low inter-specific and high intra-specific morphological variability makes morphology-based identification extremely difficult within this genus, and has led to molecular tools being employed to ensure accurate diagnoses. rDNA markers are widely used for the identification of nematodes while the Cytochrome Oxidase I gene (COI) remains relatively unexplored despite its role as the standard barcode for almost all animal groups. To explore its suitability as a diagnostic tool, we studied a fragment of the mtCOI region of the four main plant-parasitic Aphelenchoides within a phylogenetic framework. We generated 69 mtCOI and 123 rDNA sequences of diverse Aphelenchoides taxa; 67 belong to the main plant-parasitic species including the first mtCOI sequence of A. fragariae and the first mtCOI and 28S sequences of A. subtenuis. mtCOI had a similar success rate for PCR amplification. Phylogenetic trees based on the three studied markers are largely in agreement with one another, validating their use for Aphelenchoides diagnosis; additionally, we were able to locate several misidentified sequences of plant-parasitic Aphelenchoides in existing databases. The concatenated analysis from the three markers resulted in a more robust insight into the phylogeny and evolution of Aphelenchoides, revealing that plant-parasitism has evolved independently at least three times within this genus, presumably from fungal-feeding ancestors.     

Integration of environmental, agronomic, and economic aspects of fertilizer management

Nitrogen fertilization is a substantial source of nitrogen-containing trace gases that have both regional and global consequences. In the intensive wheat systems of Mexico, typical fertilization practices lead to extremely high fluxes of nitrous oxide (N2O) and nitric oxide (NO). In experiments, lower rates of nitrogen fertilizer, applied later in the crop cycle, reduced the loss of nitrogen without affecting yield and grain quality. Economic analyses projected this alternative practice to save 12 to 17 percent of after-tax profits. A knowledge-intensive approach to fertilizer management can substitute for higher levels of inputs, saving farmers money and reducing environmental costs.     

Modeling a farm population to estimate on-farm compliance costs and environmental effects of a grassland extensification scheme at the regional scale

We used a farm-level modeling approach to estimate on-farm compliance costs and environmental effects of a grassland extensification scheme in the district of Ostprignitz-Ruppin, Germany. The behavior of the regional farm population (n = 585) consisting of different farm types with different production orientations and grassland types was modeled under the presence and absence of the grassland extensification scheme using the bio-economic model MODAM. Farms were based on available accountancy data and surveyed production data, while information on farm location within the district was derived from a spatial allocation procedure. The reduction in total gross margin per unit area was used to measure on-farm compliance costs. A dimensionless environmental index was used to assess the suitability of the scheme to reduce the risk of nitrate-leaching.Calculated on-farm compliance costs and environmental effects were heterogeneous in space and farm types as a result of different agricultural production and site characteristics. On-farm costs ranged from zero up to almost 1500 Euro/ha. Such high costs occurred only in a very small part of the regional area, whereas the majority of the grassland had low on-farm costs below 50 Euro/ha. Environmental effects were moderate and greater on high-yield than on low-yield grassland. The low effectiveness combined with low on-farm costs in large parts of the region indicates that the scheme is not well targeted. The soft scheme design results from an attempt to achieve environmental and rural development objectives with only one scheme. Improving the efficiency of the scheme would require designing separate instruments for the two distinct objectives. This is in line with the Tinbergen rule, which states that consistent economic policy requires that the number of instruments equals the number of targets.     

Replacement of Rice Flour by Meat Flour Mechanically Separated from Tilapia on the Technological,Nutritional, and Sensory Quality of Salted Gluten-free Cookies

ABSTRACT

This work evaluated the technological, bacteriological, and sensorial quality of cookies produced with increasing levels (0%, 10%, 20%, 30%, and 40%) of mechanically separated meat flour from tilapia (MSMF) to replace rice flour (RF) in order to identify the optimal level without compromising the overall quality of the product. The cookies were analyzed for expansion index (EI), specific volume (SV), hardness, color, water activity (a_w ), coagulase-positive staphylococci, coliforms at 45°C, Salmonella spp., and sensory acceptance. The inclusion of MSMF affected (P < .05) some characteristics such as EI, SV, a_w , hardness, and color (L*, a*, b*), but all formulations met the legal bacteriological standards. Cookies with 20% substitution of RF by MSMF presented 58.82% carbohydrates, 18.53% proteins, and 11.31% lipids, and was the most accepted (P < .05); 51% of consumers rated it with a score of six or higher (above I liked slightly). It is concluded that the substitution of 20% of RF by MSMF can be used for nutritional enrichment of widely consumed conventional products.     

Leech (Myzobdella lugubris) infestations in largemouth bass (Micropterus salmoides) in Back Bay,Virginia, USA

Back Bay is an oligohaline, coastal bay in southeast Virginia, USA. Since 2004, leeches have been observed in the oral cavities of largemouth bass (Micropterus salmoides) in this body of water. Leeches (Myzobdella lugubris) have previously been documented in the oral cavities of largemouth bass in the Currituck Sound, which is confluent with Back Bay on its southern border. Supplemental stocking of largemouth bass in Back Bay since 2009 has resulted in an increasing population; however, concern exists that leech infestation may be negatively affecting health of larger fish, which are still less abundant than expected. Despite the wide distribution of this leech, there is little available literature regarding its health impacts on hosts. In this study, we examine potential impacts of oral leech infestations on stress markers and haematological parameters of largemouth bass in Back Bay. No significant changes in plasma glucose or cortisol were observed between leech‐infested and uninfested fish, and haematological parameters were not significantly different between the groups. Further, there was no evidence of systemic infections associated with leech infestation.     

Design, loading, and water quality in recirculating systems for Atlantic Salmon (Salmo salar) at the USDA ARS National Cold Water Marine Aquaculture Center (Franklin, Maine)

The Northeastern U.S. has the ideal location and unique opportunity to be a leader in cold water marine finfish aquaculture. However, problems and regulations on environmental issues, mandatory stocking of 100% native North American salmon, and disease have impacted economic viability of the U.S. salmon industry. In response to these problems, the USDA ARS developed the National Cold Water Marine Aquaculture Center (NCWMAC) in Franklin, Maine. The NCWMAC is adjacent to the University of Maine Center for Cooperative Aquaculture Research on the shore of Taunton Bay and shares essential infrastructure to maximize efficiency. Facilities are used to conduct research on Atlantic salmon and other cold water marine finfish species. The initial research focus for the Franklin location is to develop a comprehensive Atlantic salmon breeding program from native North American fish stocks leading to the development and release of genetically improved salmon to commercial producers. The Franklin location has unique ground water resources to supply freshwater, brackish water, salt water or filtered seawater to fish culture tanks. Research facilities include office space, primary and secondary hygiene rooms, and research tank bays for culturing 200+ Atlantic salmon families with incubation, parr, smolt, on-grow, and broodstock tanks. Tank sizes are 0.14 m³ for parr, 9 m³ for smolts, and 36, 46 and 90 m³ for subadults and broodfish. Culture tanks are equipped with recirculating systems utilizing biological (fluidized sand) filtration, carbon dioxide stripping, supplemental oxygenation and ozonation, and ultraviolet sterilization. Water from the research facility discharges into a wastewater treatment building and passes through micro-screen drum filtration, an inclined traveling belt screen to exclude all eggs or fish from the discharge, and UV irradiation to disinfect the water. The facility was completed in June 2007, and all water used in the facility has been from groundwater sources. Mean facility discharge has been approximately 0.50 m³/min (130 gpm). The facility was designed for stocking densities of 20–47 kg/m³ and a maximum biomass of 26,000 kg. The maximum system density obtained from June 2007 through January 2008 has approached 40 kg/m³, maximum facility biomass was 11,021 kg, water exchange rates have typically been 2–3% of the recirculating system flow rate, and tank temperatures have ranged from a high of 15.4 °C in July to a low of 6.6 °C in January 2008 without supplemental heating or cooling.     

Nerve insensitivity resistance to pyrethroids in Heliothine Lepidoptera

A neurophysiological assay developed previously was used to assess the incidence of nerve insensitivity resistance to synthetic pyrethroids in field strains of Helicoverpa armigera. Almost 70% of individuals from a sample of a highly pyrethroid-resistant population from Jiangsu Province, China were nerve-insensitive. Subsequent selection resulted in a strain homogeneous for expression of this mechanism. Likewise, over 95% of a sample from a strain of the insects from Andhra Pradesh, India were nerve-insensitive and a homogeneous strain was developed. Development of a nerve-insensitive laboratory strain of Heliothis virescens was undertaken but homozygosity could not be obtained. It is suggested that high fitness costs may be associated with this mechanism. The incidence of nerve insensitivity in Heliothine pests is reviewed and the role of phenotypic expression assays in molecular studies highlighted. ©1997 SCI