Genetic diversity and mating system of <Emphasis Type="Italic">bracatinga</Emphasis> (<Emphasis Type="Italic">Mimosa scabrella</Emphasis>) in a re-emergent agroforestry system in southern Brazil

Bracatinga (Mimosa scabrella) is a legume tree species common in the early stages of succession in Araucaria angustifolia forests in southern Brazil. Bracatinga can form high-density monospecific stands called bracatingais. Its traditional management for charcoal production involves maintenance of the seed bank. Our objective was to analyze the genetic diversity and structure of bracatingais to understand the mechanisms by which intraspecific diversity of M. scabrella is created and maintained in landscapes managed by family farmers in their agroforestry mosaics. We analyzed 14 bracatingais using 8 allozyme loci. We compared parental and progeny generation indices (7 loci) and described the mating system (9 loci) of two progenies. Overall diversity was high: A = 2.69, H _o = 0.257, H _e = 0.382 and similar between populations. Overall fixation (F = 0.364) was similar to the fixation index (f = 0.329). The genetic divergence among populations was low (Θ_p = 0.052) but significant. The progenies’ genetic diversity values were similar to those of the previous generation (H _{e pop11} = 0.342 vs. 0.420/H _{e pop10} = 0.432 vs. 0.400). Progenies were compatible with half-sib and full-sib crossing expectations (θ _xy  = 0.204 and 0.194). Our data showed that there is a tendency for genetic structuring caused not only by the reproductive system but also by genetic drift. It is very likely that the high genetic diversity is amplified by internal migration within each bracatingal. This study showed that current landscape management can contribute to maintaining high levels of bracatinga genetic diversity, which contributes to its regional conservation.     

Spectral and time-resolved fluorescence signature of four weed species as affected by selected herbicides

In the present study we show for the first time the suitability of the laser-induced fluorescence technique to evaluate in vivo herbicide-induced damages as revealed by changes of fluorescence spectra and lifetime. Four herbicides of different modes of action (glyphosate, bromoxynil, mesotrione, and amitrole) were selected and applied to four weed species (Stellaria media, Setaria viridis, Chenopodium album, and Viola arvensis). Modifications of the fluorescence signature depended on the agrochemical – plant species interaction as well as on the time after application. Measurements in the red and far-red spectral region reveal disturbances in the functionality of the photosynthetic apparatus and chlorophyll concentration, e.g. after application of bromoxynil or mesotrione. Recordings in the blue and green spectral regions indicate changes of both amount and composition of specific fluorophores, i.e. after application of glyphosate and amitrole. In all spectral measurements, the position of peak maxima was not affected by herbicide application. The fluorescence lifetime, expressed as LTmean or as lifetime 1 (LT1, short-duration) and LT2 (long-duration) fractions, provided additional information to the spectrally resolved data. Thereby, significant alterations of the lifetime duration and fractional characteristics were observed at specific wavelengths, e.g. after application of bromoxynil, mesotrione, or amitrole.     

Spinosad as an effective larvicide for control of Aedes albopictus and Aedes aegypti, vectors of dengue in southern Mexico

BACKGROUND: Field trials were conducted during the wet and dry seasons in periurban and semi‐rural cemeteries in southern Mexico to determine the efficacy of a suspension concentrate formulation of spinosad (Tracer 480SC) on the inhibition of development of Aedes albopictus L. and Ae. aegypti Skuse. For this, oviposition traps were treated with spinosad (1 or 5 mg L^?1), Bacillus thuringiensis israelensis (Bti, VectoBac 12AS), a sustained release formulation of temephos and a water control. RESULTS: Ae. albopictus was subordinate to Ae. aegypti during the dry season, but became dominant or codominant during the wet season at both sites. The two species could not be differentiated in field counts on oviposition traps. Mean numbers of larvae + pupae of Aedes spp. in Bti‐treated containers were similar to the control at both sites during both seasons. The duration of complete absence of aquatic stages varied from 5 to 13 weeks for the spinosad treatments and from 6 to 9 weeks for the temephos treatment, depending on site, season and product concentration. Predatory Toxorhynchites theobaldi Dyar and Knab suffered low mortality in control and Bti treatments, but high mortality in spinosad and temephos treatments. Egg counts and percentage of egg hatch of Aedes spp. increased significantly between the dry and wet seasons, but significant treatment differences were not detected. CONCLUSION: Temephos granules and a suspension concentrate formulation of spinosad were both highly effective larvicides against Ae. aegypti and Ae. albopictus. These compounds merit detailed evaluation for inclusion in integrated control programs targeted at Ae. aegypti and Ae. albopictus in regions where they represent important vectors of human diseases. Copyright © 2010 Society of Chemical Industry     

Evaluation of the Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate in Two Chilean Soils

ABSTRACT

Two Chilean soils were used to evaluate the performance of the nitrification inhibitor 3,4-dimetilpirazol phosphate (DMPP) added to ammonium-sulfate-nitrate (ASN) in comparison with traditional nitrogen (N) sources and different N-application forms. Two experiments were conducted: In the first, broccoli (Brassica oleracea var. italica) plants were cultivated in pots under greenhouse conditions, and received a N-fertilization equivalent to 150 Kg N ha^?1 as ASN+DMPP (one application), urea (two splits), and sodium-potassium nitrate (three splits). In the second, ryegrass (Lolium spp.) plants were grown in pots under shading conditions. In this case, ASN+DMPP and urea were applied at N rates equivalent to 150 and 300 Kg N ha^?1 in a single application. In the first experiment, ASN+DMPP increased dry-matter production, maintained a higher N content in the soil (at least until the middle of the growing period), and improved fertilizer N-use efficiency (FUE) in one soil. There were no significant differences in N-leaching losses. In the ryegrass experiment, ASN+DMPP increased dry-matter production and FUE, while N-leaching losses were reduced. Treatments with ASN+DMPP maintained higher N levels in soil throughout the growing period, and there were no significant differences in the available N fraction between the two N rates. The use of DMPP-containing fertilizers may be a good alternative for increasing FUE.     

The influence of cultivar and plant age on the chemical composition of field-grown cassava leaves and roots

The chemical composition, including the proximal composition, cyanide and amino acid concentrations of leaves and root tissues, as well as the starch and sugar concentrations of root peel and parenchyma, of low-(M Col 113), intermediate-(M Col 22 and the hybrid CM 342-170) and high-(M Col 1684) cyanide-containing cassava cultivars at four plant ages (6, 8, 10 and 12 months) is presented. The local cultivar (M Col 113) showed lower leaf and root parenchyma dry matter contents, lower crude fiber and crude protein levels in root peel, a higher sugar content and lower cyanide concentration in root tissues, than the other three cultivars (M Col 22, CM 342-170 and M Col 1684). Most of the parameters studied were affected by the cultivar as well as by plant age. Less variability was observed for all criteria in the root parenchyma than in the leaves and root peel. The sulfur-containing amino acids were low in all tissues analyzed and a high concentration of arginine was found in the root tissue samples. The cyanide concentration of root parenchyma was less variable than that of leaves and root peel; the cultivar M Col 1684 showed a higher cyanide concentration in the parenchyma (900 to 1000 mg/kg DM) than the other three cultivars, which ranged from 100 to 200 mg/kg DM. The local cultivar (M Col 113) was the only one in which the cyanide concentration in leaves was higher than that of the root peel. The hybrid CM 342-170 produced roots with the highest dry matter and starch concentrations.     

Growth,behavioural, serum biochemical and morphological changes in female rabbits fed high-fat diet

This study aimed to determine whether high-fat diet (HFD) could cause growth, behavioural, biochemical and morphological changes in young female rabbits. Thirty-six female rabbits were randomly divided into two groups fed with either a high-fat diet (HFD) or a standard normal diet (SND) for 5 weeks. Growth and behavioural changes were recorded during the 5-week feeding period. Tissue samples, including blood and adipose tissue, were obtained after slaughter. HFD rabbits weighed more by the end of the feeding period, had a higher percent body weight and adipose tissue weight change and had longer body and bust lengths than SND rabbits. HFD rabbits significantly reduced their feed intake and feeding frequency during the fourth and fifth weeks. HFD rabbits also showed lower frequency of drinking and resting and increased stereotypical behaviour. Besides, HFD rabbits showed significant physiological abnormalities. HFD rabbits had higher serum cholesterol (TC) and triglycerides (TG) levels than SND rabbits at the end of the feeding period, and higher free fatty acid (FFA) levels than rabbits in the SND group after the third week of feeding. Serum thyroxine (T4) increased significantly in week 2 and week 5 and triiodothyronine (T3) increased significantly in week four. However, there was no significant change in serum glucose (GLU) and insulin (INS) levels. Additionally, HFD reduced the area and diameter of perirenal and subcutaneous fat cells and increased their density. Our findings suggest that HFD rabbits had higher weight gains, accumulation of fat, and more behavioural changes than SND rabbits. Although high levels of fat in the diet had a low impact on hyperglycaemia, it could lead to hyperlipidemia and hyperthyroidism. Our results also suggest that sustained HFD may cause the proliferation of adipocytes in young female rabbits.     

Rain-induced removal of copper from apple leaves: Influence of rain properties and tank-mix adjuvants on deposit characteristics at the micro scale

Application of copper fungicides is an integrative component in the control of apple scab. As shown in the past, tank-mix adjuvants might reduce the rain-induced removal of active ingredients. The aims of this study were a) to characterize the impact of defined rain amount on the removal of Cu-oxychloride (Cu-Ox) and Cu-hydroxide (Cu-Hyd) from apple seedling leaves, b) to examine the influence of ethoxylated seed oil adjuvants on deposit properties at the micro scale and their possible influence in reducing the fungicide erosion from the leaves, and finally c) to evaluate the influence of previous adjuvant application on the rainfastness of copper ions. Losses of Cu-Hyd and Cu-Ox from seedling leaves exposed to 5 mm heavy rain reached almost 80% of the original Cu load. Wash-off extent of Cu-Ox could be reduced by using the rapeseed oil ethoxylate RSO 5 (47%), the linseed oil ethoxylate LSO 10 (47%), or the soybean oil ethoxylate SBO 10 (40%). However, in case of Cu-Hyd, none of the adjuvants was able to increase the tenacity of the copper on the leaves. Rainfall removed the bulky deposits and induced changes in the typical shape of the crystals. Furthermore, a reorganization of the spatial distribution of the remaining active ingredient (a.i.) was induced, which was very often embedded in a thin layer of adjuvants. In general, the adjuvants had a significant impact on droplet spread, whereas the area effectively covered with the a.i. was affected to a lesser extent. For both Cu-Hyd and Cu-Ox rewetting of the original deposit under controlled conditions resulted in an increased spread area but reduced the area effectively covered with Cu. Our results showed no clear relationship between the area covered by Cu ions and their adhesion to the surface, i.e. rainfastness. Finally, our studies indicated that previous spray treatments might influence the rain-induced removal of copper.     

Co‐management in Latin American small‐scale shellfisheries: assessment from long‐term case studies

Co‐management (Co‐M), defined as the sharing of management tasks and responsibilities between governments and local users, is emerging as a powerful institutional arrangement to redress fisheries paradigm failures, yet long‐term assessments of its performance are lacking. A comparative analysis of five small‐scale Latin American shellfisheries was conducted to identify factors suggesting success and failure. In Chile, Uruguay and Mexico Co‐M produced positive effects, including stabilization of landings at low levels, increase in abundance, CPUE, unit prices and revenues per unit of effort, and reduced interannual variability in several fishery indicators, particularly in landings. Co‐M was successful because it was mainly bottom‐up implemented and accompanied by‐catch shares (spatial property rights and community quotas). By contrast, Co‐M implementation was unable to prevent the collapse of the Galapagos sea cucumber fishery, as reflected by a decrease in abundance and CPUE. Negative effects were also observed in the Galapagos spiny lobster fishery during Co‐M implementation. However, recovery was observed in recent years, reflected in a stabilization of fishing effort and the highest CPUE and economic revenues observed since the beginning of the Co‐M implementation phase. The combined effects of market forces, climate variability and a moratorium on fishing effort were critical in fishery recovery. We conclude that Co‐M is not a blueprint that can be applied to all shellfisheries to enhance their governability. These social–ecological systems need to be managed by jointly addressing problems related to the resources, their marine environment and the people targeting them, accounting for their socioeconomic and cultural contexts.     

The native South American crayfishes (Crustacea,Parastacidae): state of knowledge and conservation status

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