Distribution and diversity of leaf-cutting ants in Northeastern Argentina: species most associated with forest plantations

Abstract

Leaf-cutting ants (LCA) are considered one of the main herbivores and one of the most destructive pest insects of the Neotropics. Northeastern Argentina harbors the greatest species richness of these ants and in turn comprises the highest surface with forest plantations. Our aim was to establish which species of leaf-cutting ants are most commonly associated with forest plantations by analyzing their geographic distribution using published and unpublished species occurrence data. Also, estimate their potential areas of distribution along a latitudinal gradient that entirely encompasses northeastern Argentina using Ecological Niche Modeling. Only seven of the 20 species recorded were strongly associated with productive systems along the gradient, but only 2–3 species in each region could be considered high-risk species for forest plantations. High-risk species composition shows a turnover between regions. Our models show the potential distribution areas where LCA could become more abundant and dominant, and possibly causing a detrimental effect on the forest plantations in the studied region. We find that ecological niche models are useful tools to assess the environmental suitability of important LCA.     

Assessment of dietary lipid sources in tropical gar,Atractosteus tropicus larvae: Growth parameters and intermediary lipogenic gene expression

Five experimental diets containing different lipid sources, fish oil (D1), soybean lecithin (D2), corn oil (D3), canola oil (D4) and olive oil (D5), were evaluated in Atractosteus tropicus larvae for the relative gene expression of the enzymes fatty acid synthase (fas), acetyl‐CoA carboxylase 1 (acc1) and carnitine palmitoyltransferase 1C (cpt1c), in addition to their effects on larval growth, survival and cannibalism during a 30‐day feeding trial. Higher growth and survival were obtained in treatments D1 and D2, and lower performance in diets D3, D4 and D5. The highest levels of expression of fas and acc1 occurred in larvae fed with D1, which contained high amounts of n‐3 long‐chain polyunsaturated fatty acids (LC‐PUFA), mainly DHA and EPA FA are regulators of lipogenesis. The higher cpt1c expression in plant‐based diets is attributed to the fact that these diets are rich in α‐linolenic acid (ALA) and low DHA, EPA and ARA levels that favour ß‐oxidation. In conclusion, the diets with fish oil (D1) and soybean lecithin (D2) were the best treatments for larval growth, survival and cannibalism and thus appear to meet both lipid and energy requirements of A. tropicus larvae, meanwhile the use of vegetable oils influences the expression of intermediary lipogenic genes.     

Intermediary metabolic response and gene transcription modulation on the Sub-Antarctic notothenioid Eleginops maclovinus (Valenciennes, 1930) injected with two strains of Piscirickettsia salmonis

Pathogen interactions with cultured fish populations are well studied, but their effects on native fishes have not been characterized. In Chile, the disease caused by bacterial species Piscirickettsia salmonis represents one of the main issues and is considered to be one of the important pathogens in the field of aquaculture. They have been found to infect native fish. Therefore, it is necessary to understand the impact of P. salmonis on native species of local commercial value, as well as the potential impact associated with the emergence of antibiotic-resistant strains of P. salmonis. Due to this purpose, the native fish Eleginops maclovinus was used in our study. Fish were randomly distributed in tanks and intraperitoneally inoculated with two strains of P. salmonis. No mortality was recorded during the experiment. Cortisol, glucose and total α-amino acid levels increased in fish injected with AUSTRAL-005 strain compared to sham-injected and LF-89-inoculated fish. Moreover, results showed an increase in the activity of carbohydrates and lipids metabolism in liver; and an increase in the carbohydrates, lipids and total α-amino acid metabolism in muscle after injection with AUSTRAL-005. Our results suggest that P. salmonis modulates the physiology of E. maclovinus and the physiological impact increase in the presence of the antibiotic-resistant strain AUSTRAL-005.     

ADP-Glucose Pyrophosphorylase Is Located in the Plastid and Cytosol in the Pulp of Tropical Banana Fruit (Musa acuminata)

Plant Foods for Human Nutrition - ADP-glucose pyrophosphorylase (AGPase) is a key enzyme of starch synthesis in seeds, tubers and fruits. UDP-glucose pyrophosphorylase (UGPase) is an important...     

Breeding Differently: Participatory Selection and Scaling Up Innovations in Colombia

Global challenges like sustainable development, climate change, malnutrition and gender inequality can be tackled from an agricultural perspective. Micronutrient deficiency is a major problem for the health and food security of the population. In Colombia, iron deficiencies affect 32% of the children under the age of five; and 43% of the Colombian population have zinc and vitamin A deficiencies. We designed and implemented a research-for-development programme that links agriculture and nutrition through a two-stage project. In the first stage, we selected three new yellow potato cultivars with better nutritional contents, higher yield and better resistance to late blight than the traditional yellow cultivars. We characterized the Colombian germplasm, Solanum tuberosum Group Phureja, for its nutritional attributes. During this stage, studies of the social and nutritional status of the communities were also conducted. In the second stage, we focused on scaling up new potato cultivars to reach potato producers and consumers by promoting the production and marketing of good quality seed potatoes, by establishing four Rural Entrepreneurs Nuclei. The programme promotes gender equity, good dietary habits, the consumption of more nutritious potatoes and empowers local leadership to strengthen governance. Field work was conducted in southern and central regions of Colombia by employing social strategies such as the Family Farming Community Schools. In 50% of the cultivated area, we are replacing the originally used traditional yellow potatoes by the new, more nutritious, potatoes to reach 6 million consumers. A good quality seed system for small-scale potato growers has been implemented. These achievements have been reached through a comprehensive approach in a period of two years.     

Effect of the addition of Chaetoceros calcitrans,Navicula sp. and Phaeodactylum tricornutum (diatoms) on phytoplankton composition and growth of Litopenaeus vannamei (Boone) postlarvae reared in a biofloc system

The aim of this study was to evaluate the effect of the addition of Chaetoceros calcitrans, Navicula sp. and Phaeodactylum tricornutum (diatoms) on phytoplankton composition and the growth of Litopenaeus vannamei postlarvae reared in a biofloc system . Four treatments were used: BFT (biofloc system without feed and no addition of diatoms); BFT‐F (biofloc system with feed and no addition of diatoms); BFT‐D (biofloc system with the addition of diatoms and no feed); and BFT‐FD (biofloc system with the addition of feed and diatoms), all in triplicate. The shrimp (16 ± 0.02 mg) were stocked at 2500 postlarvae m^?3 and fed a commercial feed. Diatoms were added on the 1st, 5th, 10th and 15th day at a density of 5 × 10⁴ cells mL^?1 for each species. No significant differences (P > 0.05) between treatments were observed for gross primary production, net ecosystem production and water column respiration rate. However, significant differences (P < 0.05) were observed for nitrite, orthophosphate, alkalinity, final weight, weight gain, yield, feed conversion ratio (FCR), phytoplankton and cyanobacteria composition. The BFT‐FD treatment had better performance parameters for final weight (270 mg), weight gain (254 mg), yield (0.67 Kg m^?3) and FCR (0.61), indicating the benefits of the diatoms C. calcitrans, Navicula sp. and P. tricornutum for decreasing cyanobacteria and improving growth of L. vannamei postlarvae reared in biofloc systems.     

Some Nutritional Characteristics of Enzymatically Resistant Maltodextrin from Cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz) Starch

Cassava (Manihot esculenta Crantz) native starch was treated with pyroconversion and enzymatic hydrolysis to produce a pyrodextrin and an enzyme-resistant maltodextrin. Some nutritional characteristics were quantified for both compounds. Pyroconversion was done using a 160:1 (p/v) starch:HCl ratio, 90 °C temperature and 3 h reaction time. The resulting pyrodextrin contained 46.21% indigestible starch and 78.86% dietary fiber. Thermostable α-amylase (0.01%) was used to hydrolyze the pyrodextrin at 95 °C for 5 min. The resulting resistant maltodextrin contained 24.45% dextrose equivalents, 56.06% indigestible starch and 86.62% dietary fiber. Compared to the cassava native starch, the pyrodextrin exhibited 56% solubility at room temperature and the resistant maltodextrin 100%. The glycemic index value for the resistant maltodextrin was 59% in healthy persons. Its high indigestible starch and dietary fiber contents, as well as its complete solubility, make the resistant maltodextrin a promising ingredient for raising dietary fiber content in a wide range of foods, especially in drinks, dairy products, creams and soups.     

Effect of dietary protein content on growth rate,survival and body composition of juvenile cauque river prawn,Macrobrachium americanum (Bate 1868)

We determined the effect of four concentrations of dietary crude protein, 30.7, 37.2, 41.8 and 46.8% on growth rate, survival and body composition of the juvenile cauque river prawn (Macrobrachium americanum). The prawns were hatched in the laboratory from the spawn of one wild ovigerous female. Prawns consuming 37.2% crude protein reached a final weight of 0.58 g (feed conversion ratio of 2.15), which was significantly better than the other treatments. Survival was 100% in all treatments. Protein content in the diets had no significant effect on whole body proximate composition and amino acid profile. Juveniles consuming the 37.2% crude protein diet grew faster than those fed the other diets. Specific growth rate was adjusted to the two‐slope broken‐line regression analysis model to estimate the optimal protein requirement. In conclusion, these results demonstrated that the 37.2% protein level diet is optimal for juvenile cauque river prawn M. americanum in the experimental conditions of this study.     

Productive performance of juvenile freshwater prawns Macrobrachium rosenbergii in biofloc system

The aim of this study was to compare two rearing systems for freshwater prawn Macrobrachium rosenbergii: one with use of a recirculating aquaculture system with biofilters (RAS) and another with use of microbial flocs (F). Thirty postlarvae of freshwater prawn with an initial average weight of 0.13 ± 0.05 g were randomly stocked in six experimental units with 0.20 m² and volume of 50 L. The experiment lasted thirty days. Dissolved oxygen, temperature and pH were monitored daily; ammonia concentration was determined three times per week; nitrite concentration, alkalinity and hardness were measured weekly. For the formation of microbial floc, molasses was used to keep the ammonia concentrations within safe levels for prawn farming. The variables of water quality remained within the suitable range for the production of the species, except for ammonia concentrations at the F treatment, which exceeded the safe levels. At the end of the experiment, the following parameters were evaluated: survival, specific growth rate, weight gain and feed conversion rate. Differences were found only in feed conversion rate with better values on RAS treatment. The microorganisms present in the RAS and F treatment were also evaluated. The densities of rotifers, amoebas and total bacteria were higher at the F treatment although the same organisms were found at the RAS treatment. The results of this study showed the possibility of rearing M. rosenbergii in biofloc system technology.     

Vitamin A functions and requirements in fish

Vitamin A (VA) is an essential dietary nutrient for fish and plays an important role in a range of physiological processes including vision, reproduction, embryogenesis, growth and differentiation and maintenance of epithelial cells. Knowledge of effects of VA on aquatic organisms is limited, but new information continues to be published. The aim of the present review is to present an overview of the dietary requirements and functions of VA in fish of commercial importance in aquaculture production. The effects of VA on reproduction and early embryonic development are described, and the estimated dietary requirements for VA of several species of fish are discussed. New research findings on how VA requirements vary with the life stages of fish are explored that will expand understanding of the complex role of VA. Sources of VA in feeds are described, and the potential need to consider how changes in fish feed formulations towards higher use levels of sustainable ingredients may affect dietary VA supplementation recommendations is discussed.