Limnology of Macrobrachium amazonicum grow‐out ponds subject to high inflow of nutrient‐rich water and different stocking and harvest management

We evaluated the water characteristics and particle sedimentation in Macrobrachium amazonicum (Heller 1862) grow‐out ponds supplied with a high inflow of nutrient‐rich water. Prawns were subject to different stocking and harvesting strategies: upper‐graded juveniles, lower‐graded juveniles, non‐graded juveniles+selective harvesting and traditional farming (non‐grading juveniles and total harvest only). Dissolved oxygen, afternoon N‐ammonia and N‐nitrate and soluble orthophosphate were lower in the ponds in comparison with inflow water through the rearing cycle. Ponds stocked with the upper population fraction of graded prawns showed higher turbidity, total suspended solids and total Kjeldahl nitrogen than the remaining treatments. An increase in the chemical oxygen demand:biochemical oxygen demand ratio from inlet (4.9) to pond (7.1–8.0) waters indicated a non‐readily biodegradable fraction enhancement in ponds. The sedimentation mean rate ranged from 0.08 to 0.16 mm day^?1 and sediment contained >80% of organic matter. The major factors affecting pond ecosystem dynamic were the organic load (due to primary production and feed addition) and bioturbation caused by stocking larger animals. Data suggest that M. amazonicum grow‐out in ponds subjected to a high inflow of nutrient‐rich water produce changes in the water properties, huge accumulation of organic sediment at the pond bottom and non‐readily biodegradable material in the water column. However, the water quality remains suitable for aquaculture purposes. Therefore, nutrient‐rich waters, when available, may represent a source of unpaid nutrients, which may be incorporated into economically valued biomass if managed properly.     

Fermented earthworms as a feed additive enhances non-specific immune response in catfish (Clarias gariepinus)

Catfish which is an important component of global freshwater aquaculture production is also prone to a wide range of diseases resulting in economic losses. Improvement of the immune status of catfish is a promising preventive approach to control disease. The purpose of this study was to determine the effect of fermented earthworms as a feed additive on the non-specific immune response of walking catfish (Clarias gariepinus). Earthworms were fermented by inoculation with a bacterial mixture of Bacillus spp. and Lactococcus raffinolactis. The study featured a completely randomized design, with five treatments in quadruplicate. The various treatments consisted of fermented earthworms supplemented (FE) at at 0%, 2.5%, 5%, 7.5%, and 10% (w/w). Catfish with an average weight of 15 g were stocked at a density of 50 fish per 50 L/tank, reared for 2 months, and fed thrice a day at a feeding rate of 3% of total boby weight. The parameters observed included phagocytic activity (PA), phagocytic index (PI), extracellular respiratory burst, leucocyte differentiation, super oxide dismutase (SOD), natural agglutination, leucocrit, and hematocrit. Results showed that that FE supplemented at 2.5% significantly increased the respiratory burst activity, hematocrit, PA, PI, SOD, and leucocyte differentiation (P?<?0.05) but did not affect natural agglutination. The results collectively suggest that FE as a feed additive is an effective and applicable strategy to improve the non-specific immunity of catfish.

     

The role of rain in dispersal of the primary inoculum of Plasmopara viticola

Although primary infection of grapevines by Plasmopara viticola requires splash dispersal of inoculum from soil to leaves, little is known about the role of rain in primary inoculum dispersal. Distribution of rain splashes from soil to grapevine canopy was evaluated over 20 rain periods (0.2 to 64.2 mm of rain) with splash samplers placed within the canopy. Samplers at 40, 80, and 140 cm above the soil caught 4.4, 0.03, and 0.003 drops/cm(2) of sampler area, respectively. Drops caught at 40 and 80 cm (1.5 cm in diameter) were larger than drops at 140 cm (1.3 cm). Leaf coverage by splashed drops, total drop number, and drop size increased with an increase in the maximum intensity of rain (mm/h) during any rain period. Any rainfall led to infection in potted grapevines placed outside on leaf litter containing oospores, if the litter contained germinated oospores at the time of rain; infection severity was unrelated to rain amount or intensity. Results from vineyards also indicate that any rain can carry P. viticola inoculum from soil to leaves and should be considered a splash event in disease prediction systems. Sampling for early disease detection should focus on the lower canopy, where the probability of splash impact is greatest.     

Influence of biofilm on the production of <Emphasis Type="Italic">Farfantepenaeus paulensis</Emphasis> in pens in the Patos Lagoon estuary

The objective of the present work was to determine the influence of artificial substrates that increase the area for biofilm development on the production performance of Farfantepenaeus paulensis juveniles in pens. Shrimp were stocked at a density of 20/m² in pen structures (bottom area?=?50 m²) that were installed in the Patos Lagoon estuary. Two treatments with three repetitions were analyzed, where artificial substrates (polyethylene nets—1-mm mesh size) were added to increase the area for biofilm development by 100%, and where no substrates were added. During the experimental period, the biomass and the composition of the biofilm were assessed. After 86 days of rearing, no significant differences were found in shrimp performance between the treatments (p?>?0.05). However, the examination of the chlorophyll a, dry weight, and composition of the biofilm indicated that the shrimp were actively consuming the biofilm attached to the artificial substrates. Significant decreases in the abundances of nematodes >?500 μm after the 56th day and of tintinnids and rotifers between day 28 and day 42, indicated that the shrimp were selectively predating on these organisms. Moreover, a decrease in the chlorophyll a concentration in the biofilm suggests that the shrimp were consuming the microalgae. Although the increase in the area for biofilm development did not improve shrimp performance, the shrimp presented the highest growth rates when they consumed most of the biofilm microorganisms.     

Combining sanitation and disease modelling for control of grapevine powdery mildew

Chasmothecia of Erysiphe necator form in one season, survive winter and discharge ascospores that cause primary infections and trigger powdery mildew epidemics in the next season. A strategy for powdery mildew control was developed based on (i) the reduction in overwintering chasmothecia and on (ii) spring fungicide applications to control ascosporic infections timed based on estimate risk (two to five sprays per season). Several fungicides, the hyperparasite Ampelomyces quisqualis, and a mineral oil product were first tested as separate applications in a greenhouse and in vineyards. In the greenhouse, A. quisqualis suppressed chasmothecia formation by 41 %; fungicides and mineral oil suppressed chasmothecia formation by 63 % and ascospore viability by 71 %. In vineyards, application of boscalid + kresoxim-methyl or meptyldinocap once after harvest, as well as application of A. quisqualis pre- and post-harvest, delayed disease onset and epidemic development in the following season by 1 to 3 weeks and lowered disease severity (up to the pea-sized berry stage) by 56 to 63 %. Risk-based applications of sulphur and of synthetic fungicides provided the same control as the grower spray program but required fewer applications (average reduction of 47 %). Sanitation strategies were then tested by combining products and application times (late-season, and/or pre-bud break, and/or spring). Adequate disease control with a reduced number of sprays was achieved with the following combination: two applications of A. quisqualis (pre- and post-harvest), one application of mineral oil before bud break, and model-based applications of sulphur fungicides between bud break and fruit set.     

Cover Image,Volume 73, Issue 2

The cover image, by Eugênio E. Oliveira et al., is based on the Research Article Pyrethroid resistance is associated with a kdr‐type mutation (L1014F) in the potato tuber moth Tecia solanivora, DOI: 10.1002/ps.4414 . Photo Credit: Edison Torrado‐Leon.

     

European veterinary education: a bridge to quality

The aim of this review is to provide an insight into the current state of, and future changes in, veterinary education within the European Community, as well as the role of the European Association of Establishments for Veterinary Education (EAEVE) in evaluating and raising standards of education and training. It also describes the role of EAEVE in developing strategies for changes in the future. Veterinary schools have traditionally aimed at producing the omnicompetent veterinarian at graduation. Many have questioned whether this is possible, and a recent European Commission (EC) funded market survey has confirmed that this is indeed an impossible task and has identified the requirements of society within the European Union (EU) for veterinary services in the future. There is however a need to change the current 1978 European Directive. The current mechanisms which have been used by EAEVE to evaluate over 100 veterinary schools in Europe and their relationship with other systems of appraisal are described. The future of veterinary education within the context of higher education in Europe as part of the Bologna process and in relation to standards of veterinary education worldwide are discussed. Whilst the merits of standardisation of educational quality so that there can be mutual recognition of qualifications are supported, the need to preserve the strengths associated with the diversity of approaches and teaching methods is strongly advocated.