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Piaractus mesopotamicus, is a fish usually farmed in semi-intensive systems with access to natural food and supplementary feed. This study evaluates effects of feed allowance on the productive performance, carbon turnover and proportions of nutrient (carbon) contribution of feed and natural food for the growth of pacu. Juvenile fish were stocked in fiberglass tanks and fed to 100, 75, 50, 25, 0% apparent satiety (ApS), with a practical, extruded (C4 photosynthetic pathway) feed in a randomized design trial (n=3); plankton production for simulated semi-intensive farming system condition was induced by chemical fertilization. A control treatment was set up in tanks devoid of natural food. Data on muscle stable carbon isotope ratios were used to study carbon turnover using a relative growth-based model. Low variation of the δ13C impaired fitting a turnover model curve for the 0 and 25 % ApS treatments. Fish of the 100% and 75% ApS treatments reached circa 95% and 82.85% of the carbon turnover, respectively. Extruded feed was the main nutrient source for the growth of pacu in the semi-intensive, simulated farming condition. The current study contributes to the knowledge of the relationship between feeding rates and carbon turnover rates in the pacu muscle.

Objective: The main objective of this study is to investigate diet patterns among rural and urban populations of the Center-West, Northeast, and Amazon regions of Brazil through the carbon and nitrogen isotopic composition of fingernails, recognizing that the extent of market integration is a key driver of food consumption., Materials and Methods: In the Center-West, Northeast, and Amazon regions of Brazil, fingernails were sampled in clusters encompassing a major city, town, and rural village. A total of 2,133 fingernails were analyzed. Fingernails were clipped by donors using fingernail clippers. In the laboratory, samples were cleaned then weighed in small tin capsules before being isotopically analyzed for carbon and nitrogen., Results: The overall mean δ 13 C and δ 15 N were -19.7 ± 2.8‰ and 10.6 ± 1.1‰, respectively. In the more remote villages, where access to food markets is more challenging, lower δ 13 C prevails, suggesting that Brazilian staple foods (rice, beans, and farinha) still dominate. In areas with easier access to food markets, δ 13 C values were higher, suggesting a change to a diet based on C 4 plants, typical of a Brazilian supermarket diet. The variability among inhabitants in the same location expressed by a significant inverse correlation between δ 13 C and δ 15 N fingernail values suggested that "market integration" does not affect everyone equally in each community., Discussion and Conclusion: The nutrition transition has not yet reached some remote villages in these regions of Brazil or that the nutrition transition has not yet reached all residents of these remote villages. On the other hand, in several villages there is a considerable adherence to the supermarket diet or that some residents of these villages are already favoring processed food., (© 2020 Wiley Periodicals, Inc.)

Based on the assumptions that human food is available for dogs and isotope diet-tissue differences are similar in dogs and humans, the 'canine surrogacy approach' (CSA) has been used to infer patterns of ancient populations. The goal of this study was to test the CSA in urban (Brasília and Piracicaba) and in rural (Ubatuba and Maraã) areas. The hair C and N isotope ratios of modern dogs were compared with those of human fingernails from different regions of Brazil. Our CSA results showed a correlation between dog and human isotopes values: in rural areas δ 15 N of humans and dogs was not statistically different; contrarily, in urban centres, δ 15 N of humans was approximately 1 ‰ higher (p < 0.01) than δ 15 N of dogs; humans had lower δ 13 C values (p < 0.01) than dogs in Brasília, Piracicaba and Ubatuba. In Maraã, there was not any significant difference between dogs and humans. We concluded that CSA is still valid as a first approach in modern societies. However, isotopic differences found suggest that in modern societies processed dog food is increasingly disconnecting human and dog, jeopardising the use of CSA in the future if the trend of increasing processed dog food consumption continues to occur.

The availability of accurate techniques to discriminate between marked laboratory-reared flies and unmarked wild flies captured in monitoring traps is essential for programs that integrate the Sterile Insect Technique (SIT) to manage fruit flies. In this study, the feasibility of using a stable isotope marking technique for the South American fruit fly, Anastrepha fraterculus (Wiedemann), was assessed. Wild flies were collected from apple orchards, which are a target of a SIT project in southern Brazil. To verify if adult flies could be labelled by the stable isotopes from larval diets, larvae were reared on two different C4-based diets and fruits in laboratory. To evaluate the influence of the two most common attractants applied to capture A. fraterculus (grape juice and CeraTrapTM) and the most common preservation method in fruit fly collections (ethanol), laboratory-reared flies were immersed in McPhail traps containing the respective treatments for two periods of time. Samples were analyzed in an elemental analyzer coupled to a Continuous Flow Isotope Ratio Mass Spectrometer (CF-IRMS) at CENA/USP. The δ13C signatures of flies reared on artificial diets differed significantly from the δ13C of flies whose larvae were reared on fruits and from wild flies. In contrast, the δ15N values were less conclusive and the technique could not rely solely on them. In all cases considered, the δ13C and δ15N signatures from males did not differ from females. Despite the alterations caused by the attractants tested and ethanol, laboratory-flies could be distinguished from the wild ones based on δ13C signatures. This is the first comprehensive study to demonstrate that it is possible to distinguish wild A. fraterculus from flies reared on larval diets containing C4 sugar. The first experimentally derived trophic discrimination factors were also obtained for this species. Thus, intrinsic isotope labelling can serve as a backup to conventional dye marking., Competing Interests: The authors have declared that no competing interests exist.

Highlights • δ13C and δ15N were firstly applied to test the presence of C-4 carbon in shoyu. • Authors have over interpreted their data set and critical discussion is needed. • More samples should be determined for a more reliable method validation. • Measures should be taken to eliminate isotopic fractionation before determination. Abstract In a recent paper published in this journal by Morais et al., carbon and nitrogen (N) isotopic compositions were determined by element analyzer-isotope ratio mass spectrometry (EA-IRMS), and were firstly applied to test the presence of C-4 carbon in soy sauces (shoyu) produced in Brazil. Results indicated that most of the shoyu in Brazil contained <20% soy, and the dominant cereal was maize due to its cheaper price. However, the authors have greatly over interpreted their data set and thus the subsequent conclusions drawn now require critical comment and discussion. The sample size was not enough to support any conclusion about them. In addition, the stewing process in the production of shoyu could significantly affect the degree of the isotopic fractionation, resulting in the unreliable δ13C and δ15N values of shoyu. Therefore, more samples should be determined for a more reliable method validation and several measures should be taken to eliminate or reduce the isotopic fractionation caused by external processing conditions before determination. [ABSTRACT FROM AUTHOR]

Measurements of the organic carbon inventory, its stable isotopic composition and radiocarbon content were used to deduce vegetation history from two soil profiles in arboreal and grassy savanna ecotones in the Brazilian Pantanal. The Pantanal is a large floodplain area with grass-dominated lowlands subject to seasonal flooding, and arboreal savanna uplands which are only rarely flooded. Organic carbon inventories were lower in the grassy savanna site than in the upland arboreal savanna site, with carbon decreasing exponentially with depth from the surface in both profiles. Changes in 13C of soil organic matter (SOM) with depth differed markedly between the two sites. Differences in surface SOM 13C values reflect the change from C3 to C4 plants between the sites, as confirmed by measurements of 13C of vegetation and the soil surface along a transect between the upland closed-canopy forest and lowland grassy savanna. Changes of 13C in SOM with depth at both sites are larger than the 3-4 per mil increases expected from fractionation associated with organic matter decomposition. We interpret these as recording past changes in the relative abundance of C3 and C4 plants at these sites. Mass balances with 14C and 13C suggest that past vegetational changes from C3 to C4 plants in the grassy savanna, and in the deeper part of the arboreal savanna, occurred between 4600 and 11 400 BP, when major climatic changes were also observed in several places of the South American Continent. The change from C4 to C3, observed only in the upper part of the arboreal savanna, was much more recent (1400 BP), and was probably caused by a local change in the flooding regime. [ABSTRACT FROM AUTHOR]

Stable carbon isotope ratios can be used to discriminate between wild and sterile insects that are caught in surveillance traps when 2 isotopically distinct dietary sources are available for the immature or adult stages. Artificial diets containing naturally 13C-labelled sugar can isotopically mark the adults of some tephritids, but when sexually mature flies are released in the field, their food source usually changes from a C4 to a C3 plant. Consequently, the isotopic composition of flies can change toward the isotopic signatures associated with the new diet. For isotope labelling to be more meaningful in a pest management program that integrates the sterile insect technique, it is important to know the persistence of the carbon isotope marker in field-release sterile adults. Therefore, this study was intended to assess the degree of isotopic differentiation between wild samples of Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) and flies reared on different artificial diets, and to estimate the turnover of carbon in flies after shifts to different adult diets. The whole bodies of flies reflected the overall isotopic composition of their larval diets immediately after emergence. When the adult diet was switched, the δ13C signatures of flies changed rapidly for 6 to 8 d, then reached an isotopic equilibrium with the final diet. Depletions up to -5.6 (parts per thousand) were observed in the signatures of flies switched from a C4 to a C3-based diet. However, appropriate feeding on diets with C4 sources ensured that the isotopic composition of larval diets was fixed in body structures of adult A. fraterculus, maintaining measurable 13C signals distinct from wild flies for 15 d after diet switching. No differences were found between males and females when they fed on different pre-release diets or after diet change. The 13C stable isotope proved to be a reliable marker for differentiating wild and laboratory-reared A. fraterculus flies. [ABSTRACT FROM AUTHOR]

Abstract: The carbon stable isotope ratio (δ13C) has become an important tool to determine the composition and quality of various beverages, indicating the amount of C3- and C4-sources used in brewing. Accordingly, we assessed the isotopic composition of beers produced in Brazil and abroad, in order to quantify the use of C4-sources as adjuncts. We also related the presence of such adjuncts to beer price, and compared the current results to similar studies, in order to assess any differences regarding beer composition over time. The mean δ13C value for Brazilian beers was around −22.0‰, indicating a high addition of C4-adjuncts during the brewing process. A dichotomy of beer isotopic signatures was observed: beers from large breweries had higher δ13C values (around −20.0‰) than beer from artisanal breweries (−25.0‰). Beer price per L was directly related to δ13C values in Brazil and abroad. This significant relationship, in addition to the 13C-enrichment observed in this study, may reflect a change in the Brazilian beer market, in which a greater variety of beverages are produced and marketed following traditional recipes regarding their purity. [Copyright &y& Elsevier]