Maturation and Spawning of the White Shrimp Penaeus schmitti Burkenroad, 1936, Under Large Scale Rearing Conditions

This paper describes the reproductive performance of Penueus schmitti kept under controlled conditions in a maturation facility of a commercial shrimp farm. A total of 369 females and 368 males of wild P. schmitti were used to form 9 broodstock groups. Unilateral ablation was performed on females only. Although females were not tagged, the total number of mated females ( N = 533) indicates that rematuration of the ovaries did occur. Only 9 mated females (1.69%) did not spawn and only 22 mated females (4.20%) of the remaining 524 cases did not produce viable spawns. These results indicate that a large number of viable spawns (94.18%) can be expected from P. schmitti . A minimum latency period of 6 days for the ovaries to attain full development was observed twice. The highest mating frequency occurred between the 46th and 60th days after unilateral ablation, but mating frequency remained above 2% until the 90th day. The average number of nauplii/female/spawn was 78,961 ( N = 524) and the average fertilization rate of the eggs was 73.12% ( N = 297). Usually when the pair of the spermatophores is dislodged from the thelycum of the mated female, a small sperm mass still remains between the third pair of walking legs. This condition did not show any negative effect on the fertilization rate of the eggs and nauplii production. Mating behavior displayed by P. schmitti is also described and includes three distinctive phases: a) chasing, b) mating and c) post-mating chase.     

New Insights of Turmeric Extract-Loaded PLGA Nanoparticles: Development,Characterization and In Vitro Evaluation of Antioxidant Activity

Here, we presented new insights of the development of poly(lactic-co-glycolic acid) nanoparticles containing turmeric compounds (turmeric-PLGA-NPs) using emulsion-solvent evaporation method. The nanoparticulate system was characterized by size, zeta potential, morphology, release profile, partition parameter, stability and encapsulation efficiency (%EE). Antioxidant activity studies were also evaluated. The Korsmeyer-Peppas model (M_t/M_∞ vs. t) was used to determine the release mechanisms of the studied system. Our results demonstrated the emulsion-solvent evaporation method was shown advantageous for producing turmeric-PLGA-NPs in the range of 145 nm with high homogeneity in size distribution, zeta potential of ?21.8 mV and %EE about 72%. Nanoparticles were stable over a period of one month. In vitro study showed a release of curcumin governed by diffusion and relaxation of the polymeric matrix. The partition parameter of the extract in relation to blank-PLGA-NPs was 0.111?±?0.008 M^?1, indicating a low affinity of curcumin for the polymer matrix. Antioxidant ability of the turmeric-PLGA-NPs in scavenging the radical 2,2-azinobis (3-ethylbenzothiazoline- 6-sulfonic acid) (ABTS) was inferior to free turmeric extract and showed a concentration and time-dependent profile. The study concluded that PLGA nanoparticles are potential carriers for turmeric extract delivery.

     

Modelling Wild-Oat Density in Terms of Soil Factors: A Machine Learning Approach

In crop fields, weed density varies spatially in non-random patterns. Initial knowledge of weed distribution would greatly improve weed management for Precision Agriculture operations. Site properties could be correlated to weed distribution, since the former vary among crop fields and also certain factors such as soil texture or nitrogen may condition the weed growth. This paper presents a method, based on artificial intelligence techniques, for inducing a model that appropriately predicts the heterogeneous distribution of wild-oat (Avena sterilis L.) in terms of some environmental variables. From several experiments, distinct rule sets have been found by applying a genetic algorithm to carry out the automatic learning process. The best rule set extracted was able to explain about 88% of weed variability.     

Vitamin content and amino acid composition of pickled garlic processed with and without fermentation

The effect of processing, with and without fermentation, upon the nutritional composition of pickled garlic was evaluated. On a dry basis, the fermented product had a higher content of riboflavin, alpha-tocopherol, and most individual amino acids but a lower thiamin level than the unfermented product. Ascorbic acid was totally lost during processing. The chemical scores for the unfermented and fermented product were 88 and 108%, respectively, with the limiting amino acid being leucine. Water blanching (90 degrees C for 4 min) affected only the ascorbic acid content, whereas fermentation significantly affected the contents of thiamin, ascorbic acid, and alpha-tocopherol, as well as glutamic acid and arginine. For each processing type, the effect of the preservation method and storage time on vitamins and amino acid composition was also analyzed. In the case of the fermented product, usage of the corresponding fermentation brine plus refrigerated storage was also assayed as the packing/preservation method and was found to give the best result from a nutritional standpoint.     

Soil fertility management and insect pests: harmonizing soil and plant health in agroecosystems

Cultural methods such as crop fertilization can affect susceptibility of plants to insect pests by altering plant tissue nutrient levels. Research shows that the ability of a crop plant to resist or tolerate insect pests and diseases is tied to optimal physical, chemical and mainly biological properties of soils. Soils with high organic matter and active soil biology generally exhibit good soil fertility. Crops grown in such soils generally exhibit lower abundance of several insect herbivores, reductions that may be attributed to a lower nitrogen content in organically farmed crops. On the other hand, farming practices, such as excessive use of inorganic fertilizers, can cause nutrient imbalances and lower pest resistance. More studies comparing pest populations on plants treated with synthetic versus organic fertilizers are needed. Understanding the underlying effects of why organic fertilization appears to improve plant health may lead us to new and better integrated pest management and integrated soil fertility management designs.     

Seeding and Mulching Treatments as Conservation Measures of Two Burned Soils in the Central Ebro Valley,NE Spain

The effectiveness of seeding introduced species, with or without straw mulching, was tested as a measure of post-fire erosion control in gypsiferous (Xeric Haplogypsid) and calcareous soils (Xeric Torriorthent) in Central Ebro Valley (NE-Spain). Paired control, seeding, and combined seeding and mulching plots were established in four replicated plots for each soil tested. Seeding rate was 30 g m -2 and straw mulch was applied at 100 g m -2 in each plot. Plant projective cover (total and specific), plant biomass, bare soil cover and sediment yield were determined over a 2-year period. During the first year of sampling, species introduced by seeding increased plant cover (about 30%) without significant differences observed between soils. Plant cover was similar in seeding-only and seeding-mulching treatments, although the latter treatment significantly enhanced plant weight. During the second year these differences disappeared because species introduced by seeding practically did not survive. So, the introduced herbs did not interfere with native plants. Bare soil cover remained significantly lower in treated plots than on the control plots for both soils during both years of sampling. In the second year, the reduction of bare soil was attributed to both the straw mulch and litter from the seeding species. Soil protection was significantly higher in calcareous soils than in gypsiferous soils which is related to their physical and chemical properties. Cumulative sediment yield decreased significantly over time with both treatments on both soils. Soil losses from control plots were three times higher than seeding plots and 3.3 times higher than from seeding and mulching plots in gypsiferous soils. Soil losses from control plots were two times higher than from seeding plots and 2.7 times higher than the combined seeding and mulching plots in the calcareous soils. Cumulative soil loss was higher from the gypsiferous soils than from the calcareous soils due to the lower plant cover.     

Increased CO2 emission and organic matter decomposition by leaf-cutting ant nests in a coastal environment

Leaf-cutting ants perform a vital role in the cycling of carbon and nutrients in tropical ecosystems. Nests have high levels of organic matter and refuse dumps host up to two times more soil micro-organisms than non-nest soil. The increased levels of organic matter in the soil of nests, however, can affect CO₂ emissions from soil and alter the balance of atmospheric CO₂. We aimed at assessing the effect of nests of the leaf-cutting ant Acromyrmex balzani on CO₂ emissions in a coastal area of Northeast Brazil. Results show that A. balzani nests emitted up to four times more CO₂ than the surrounding soil and emissions were positively correlated with soil moisture and soil organic matter (SOM) content. In addition, field experiments demonstrated that refuse material has a lower residence time than the leaf material brought to the colonies. Despite the high density of nests and high content of SOM compared to adjacent control soil, CO₂ emissions by A. balzani nests represent only 0.3% of the total CO₂ efflux by the studied ecosystem. Although these effluxes account for a relative small portion of the total soil CO₂ emission, they are still important for the understanding of C balance, especially when one considers the thousands of tons of CO₂ emitted each day, across entire Neotropical regions where leaf-cutting ants occur.     

Insecticidal Effect of Labramin, a Lectin-Like Protein Isolated from Seeds of the Beach Apricot Tree, Labramia bojeri, on the Mediterranean Flour Moth, Ephestia kuehniella

Abstract The objective of this work was to study the insecticidal effect of labramin, a protein that shows lectin-like properties. Labramin was isolated from seeds of the Beach Apricot tree, Labramia bojeri A. DC ex Dubard (Ericales: Sapotaceae), and assessed against the development of the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), an important pest of stored products such as corn, wheat, rice, and flour. Results showed that labramin caused 90% larval mortality when incorporated in an artificial diet at a level of 1% (w/w). The presence of 0.25% labramin in the diet affected the larval and pupal developmental periods and the percentage of emerging adults. Treatments resulted in elevated levels of trypsin activity in midgut and fecal materials, indicating that labramin may have affected enzyme-regulatory mechanisms by perturbing peritrophic membranes in the midgut of is. kuehniella larvae. The results of dietary experiments with E. kuehniella larvae showed a reduced efficiency for the conversion of ingested and digested food, and an increase in approximate digestibility and metabolic cost. These findings suggest that labramin may hold promise as a control agent to engineer crop plants for insect resistance.     

Land use history and historical soil erosion at Albersdorf (northern Germany) — Ceased agricultural land use after the pre-historical period

The Holocene landscape history and historical soil erosion were reconstructed at Albersdorf (Schleswig-Holstein, Germany) from soils and colluvial layers. In contrast to many landscapes in central Europe, agricultural land use and soil erosion were more frequent during pre-historical times, whereas it has almost ceased after the advent of history. Pre-historical soil erosion rates from about 0.1 to 6.9 t ha^− 1 a^− 1 were reconstructed with no significant differences between the prehistoric cultural phases. The study of buried soils within the soil/soil-sediment-sequences provided evidence for an acceleration of soil formation processes probably as a consequence of excessive prehistoric woodland pasture on poor sandy soils.