Towards an improved understanding of the dynamics of vineyard-infesting Scaphoideus titanus leafhopper populations for better timing of management activities

BACKGROUND: This paper deals with supervised management of Scaphoideus titanus (Homoptera Cicadellidae) and describes a phenology model designed for improving the understanding of the within‐vineyard dynamics and the timing of insect growth regulator (IGR) applications. RESULTS: The model consists of five components dealing with (a) the beginning of the post‐dormancy development of overwintering eggs, (b) the egg hatching patterns, (c) the duration of first‐instar nymphs, (d) the development and survival of subsequent instars and (e) the stochastic development of cohorts and their passage into the adult stage. Laboratory data permitted the parameterisation of temperature‐dependent development and survival functions. Field data consisting mainly of beating tray catches allowed model parameterisation and validation. The model satisfactorily predicts the dynamics of age structures, the beginning as well as the pattern of egg hatching, the occurrence of the third instar and the emergence of adults. CONCLUSION: The phenology model is useful for timing IGR applications and for setting up monitoring activities in supervised S. titanus control. The model is an entry point into an adaptive management system, in that real‐time weather and monitoring data are continuously integrated into the model for improving its explanatory and predictive capabilities. Copyright © 2011 Society of Chemical Industry     

The critical importance of an undammed river segment to the reproductive cycle of a migratory Neotropical fish

Biotelemetry, ichthyoplankton and genetic data can provide detailed information about the migratory dynamics and reproductive cycle of freshwater fishes. However, few studies have combined these techniques in Neotropical systems. The objective of this study was to examine the migratory and reproductive dynamics of Prochilodus costatus in the São Francisco River watershed, south‐east Brazil, by comparing the ecological importance of two rivers to the species, an undammed segment of the São Francisco River and a dammed segment of one of its main tributaries, the Pará River. In total, 215 fish were radio‐tagged over three years (2014–16). Eggs and larvae were sampled at seven locations and analysed by PCR to identify Prochilodus spp. ichthyoplankton. Most radio‐tagged individuals (97%) used the undammed segment of the São Francisco River as spawning migration route, even those captured and released in the Pará River. Fish migrated to spawn from late September to late November with the arrival of the rains and returned to feeding sites from December to May after spawning. The highest densities of fish eggs and larvae were recorded in the upper reaches of the São Francisco River during months of peak river discharge. Returning fish showed high fidelity to sites occupied before spawning migration. Fish spent roughly 71% of the year at feeding sites, 25% at spawning sites and 4% moving between them. This study provides novel information about the migratory dynamics of Neotropical fishes and underscores the key role of undammed river segments for the conservation of Neotropical migratory fish species.     

Plant extracts as phytogenic additives considering intake,digestibility, and feeding behavior of sheep

The objective was to evaluate the intake, digestibility, and ingestive sheep behavior with feeding phytogenic additives derived from plant extracts. Five non-emasculated sheep without defined breed at 28?±?1.81 kg initial body weight and 6 months age were used. Treatments consisted of administering four phytogenic additives from the garlic extracts, coriander seed, oregano, and pods of mesquite, plus a control treatment (without additive). The ration was composed of Tifton 85 hay grass, corn, soybean meal, and mineral salt. As experimental design, we used a 5?×?5 Latin square design (five treatments and five periods). The data were analyzed through the mixed model through the procedure PROC MIXED of software Systems Statistical Analysis version 9.1, with comparation analysis between the treatment without additive (control) with phytogenic additives produced from vegetable extracts of mesquite pod, of coriander seed, the bulb of garlic, and the oregano leaves. There were no significant differences for the nutrient intake and ingestive behavior patterns. However, the additive intake derived from mesquite pods and coriander extracts provided an increase in digestibility. Extracts from garlic, coriander, and mesquite pods can be used as phytogenic additives in feeding sheep.     

Dynamics of vanishing of maternally derived antibodies of Ungulate protoparvovirus 1 suggests an optimal age for gilts vaccination

The prevention of Ungulate protoparvovirus 1 (UPV1) infection and consequently the reproductive losses is based on vaccination of all pigs intended for breeding. As maternally derived antibodies (MDA) can interfere with the development of immunity following vaccination, it is important to know the duration of anti-UPV1 MDA to determine the optimal age for the best vaccination efficacy. To elucidate the association between dam and piglet antibody levels against UPV1 and to estimate the decrease rate of MDA, sera and colostrum of 127 gilts (before the first vaccination against UPV1; 15 days after the second vaccine dose; at farrowing; and during the second pregnancy) and sera of 276 piglets (prior to initial colostrum intake; at 7, 21, 57, 87, and 128 days-old) were tested by ELISA. Most gilts (85.8%) had anti-UPV1 antibodies before vaccination and after vaccination all were positive. At 7 days old, the majority of the piglets had anti-UPV1 antibodies, but around 57 days old, only 35.3% were positive and at 87 days old, all were negative. The estimated average half-life of MDA was 29.8 (28.8–30.9) days. A strong correlation was determined between piglet serum at 7 days old with gilt serum at farrowing time (r = 0.77, n = 248, P < 0.001) and with piglet serum at 7 days old with colostrum (r = 0.73, n = 248, P < 0.001). The MDA decreased earlier and the antibody half-life was a little longer than previously reported. Based on these findings, UPV1 vaccination can be performed earlier than usual.

     

Carbon fractions as indicators of organic matter dynamics in chestnut orchards under different soil management practices

Several studies have emphasized the negative impact of the conventional soil management (CT) system on productivity and sustainability of chestnut orchards (Castanea sativa Mill.) when compared to no-tillage with grass cover (NT). However, scarce information is available regarding the effects of these soil management systems on soil organic matter (SOM) dynamics and soil quality. SOM or soil organic carbon is a key component of soil quality and has different fractions with different lability, namely, organic C (POC), active C (AC) and hot-water extractable carbon (HWC). These are considered as indicators of changes in management-induced soil quality. Thus, a study was carried out to evaluate the effects of NT and CT systems applied in the chestnut orchards on: (i) total amount of soil organic C (TOC), including C from both organic and mineral layers; (ii) soil organic C concentration of mineral horizons (OC); (iii) labile soil organic fractions (POC, AC, HWC); (iv) and soil mineral-associated C. The study was developed in two 30-year old chestnut orchards located in Northeast Portugal, that were kept under different soil management systems (NT or CT) during the preceding 17 years. Soil samples were taken at 0–10 and 10–20 cm soil depth. No significant differences in OC concentration were observed between NT and CT, while TOC was significantly higher in NT than in CT (22.54 and 12.17 Mg/ha or 34.16 and 22.90 Mg/ha, considering the organic layer plus mineral layers at 0–10 and 0–20 cm depth (set of two depths). The NT practice led to significantly higher concentration of labile C fractions (POC, AC and HWC) than CT at 0–10 cm soil depth. These results indicate that measurement of labile soil organic C fractions, such as POC, AC and HWC, may provide a sensitive and consistent indication of changes in soil C and SOM dynamics in response to soil management practices. Overall, NT seems to ensure better soil quality than CT in chestnut orchards under Mediterranean climate conditions.     

Hydrogen peroxide removal with magnetically responsive Saccharomyces cerevisiae cells

Hydrogen peroxide (HP) is a promising chemical sanitizer for use in the food industry. Its residues have to be decomposed, usually using an enzyme process employing catalase. In order to offer an inexpensive biocatalyst and to simplify subsequent manipulation, we have prepared magnetically responsive alginate beads containing entrapped Saccharomyces cerevisiae cells and magnetite microparticles. Larger beads (2-3 mm in diameter) were prepared by dropping the mixture into calcium chloride solution, while microbeads (the diameter of majority of particles ranged between 50 and 100 microm) were prepared using the water in oil emulsification process. In general, microbeads enabled more efficient HP decomposition. The prepared microparticulate biocatalyst caused efficient decomposition of HP in water solutions (up to 2% concentration), leaving very low residual HP concentration after treatment (below 0.001% under appropriate conditions). The biocatalyst was stable; the same catalytic activity was observed after one month storage at 4 degrees C, and the microbeads could be used at least five times.     

Introduction of the entomopathogenic fungusEntomophaga maimaiga hum.,

The entomopathogenic fungusEntomophaga maimaiga was introduced into aL. dispar population situated in South Bulgaria for the first time in Europe. It was found that of all larvae collected in the five experimental plots, 6.3 % contained conidia and resting spores ofE. maimaiga, 14.2 % contained parasitoids and 2.3 % were infected with nucleopolyhedrovirus (NPV). The presence of the fungus in cadavers collected from each experimental plots and on five of the six collection dates was observed.