Effect of sugarcane varieties on the development of Mahanarva fimbriolata (Hemiptera: Cercopidae)

The sugarcane spittlebug, Mahanarva fimbriolata (Hemiptera: Cercopidae), is considered the most important pest of sugarcane harvested without the burning of trash, or green cane, in Brazil. The objective of this work was to compare the biology of M. fimbriolata on six sugarcane varieties: SP79-1011, SP80-1816, SP80-1842, SP81-3250, RB72454, and RB835486. The experiments were conducted at a temperature of 25 +/- 1 degrees C, RH of 70 +/- 10%, and a photoperiod of 14:10 [L:D]. Variety RB72454 outperformed the rest, reducing the nymphal population that fed on its roots by 50%. With regard to adults, variety SP81-3250 allowed greater mean longevity of males (38 days) and females (51 days), greater mean oviposition period (46 days), and higher mean fecundity (1215 eggs/female); these parameters were statistically different from those obtained with other varieties. For the eggs, there was no significant effect of variety on developmental time or viability. Consequently, the variety SP81-3250 should be avoided in areas predisposed to the occurrence of M. fimbriolata.

Bacterial soil community in a Brazilian sugarcane field

The assessment of bacterial communities in soil gives insight into microbial behavior under prevailing environmental conditions. In this context, we assessed the composition of soil bacterial communities in a Brazilian sugarcane experimental field. The experimental design encompassed plots containing common sugarcane (variety SP80-1842) and its transgenic form (IMI-1 - imazapyr herbicide resistant). Plants were grown in such field plots in a completely randomized design with three treatments, which addressed the factors transgene and imazapyr herbicide application. Soil samples were taken at three developmental stages during plant growth and analyzed using 16S ribosomal RNA (rRNA)-based PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and clone libraries. PCR-DGGE fingerprints obtained for the total bacterial community and specific bacterial groups - Actinobacteria, Alphaproteobacteria and Betaproteobacteria - revealed that the structure of these assemblages did not differ over time and among treatments. Nevertheless, slight differences among 16S rRNA gene clone libraries constructed from each treatment could be observed at particular cut-off levels. Altogether, the libraries encompassed a total of eleven bacterial phyla and the candidate divisions TM7 and OP10. Clone sequences affiliated with the Proteobacteria, Actinobacteria, Firmicutes and Acidobacteria were, in this order, most abundant. Accurate phylogenetic analyses were performed for the phyla Acidobacteria and Verrucomicrobia, revealing the structures of these groups, which are still poorly understood as to their importance for soil functioning and sustainability under agricultural practices.

Dosage-dependent shift in the spore community of arbuscular mycorrhizal fungi following application of tannery sludge

The controlled disposal of tannery sludge in agricultural soils is a viable alternative for recycling such waste; however, the impact of this practice on the arbuscular mycorrhizal fungi (AMF) communities is not well understood. We studied the effects of low-chromium tannery sludge amendment in soils on AMF spore density, species richness and diversity, and root colonization levels. Sludge was applied at four doses to an agricultural field in Rolandia, Parana state, Brazil. The sludge was left undisturbed on the soil surface and then the area was harrowed and planted with corn. The soil was sampled at four intervals and corn roots once within a year (2007/2008). AMF spore density was low (1 to 49 spores per 50 cm(3) of soil) and decreased as doses of tannery sludge increased. AMF root colonization was high (64%) and unaffected by tannery sludge. Eighteen AMF species belonging to six genera (Acaulospora, Glomus, Gigaspora, Scutellospora, Paraglomus, and Ambispora) were recorded. At the sludge doses of 9.0 and 22.6 Mg ha(-1), we observed a decrease in AMF species richness and diversity, and changes in their relative frequencies. Hierarchical grouping analysis showed that adding tannery waste to the soil altered AMF spore community in relation to the control, modifying the mycorrhizal status of soil and selectively favoring the sporulation of certain species.

Foundation and Perspectives of the Use of Plant Extracts as Performance Enhancers in Broilers

Feed is responsible for about 70% of broilers production costs, leading to an increasing number of studies on alternative dietary products that benefit bird performance and lower production costs. Since the 1950s, antimicrobial additives are the most frequently used performance enhancers in animal production and their positive results are observed even in high-challenge conditions. Since the 1990s, due to the ban of the use of some antibiotics as growth promoters and the growing trend of the public to consume natural products, plant extracts have been researched as alternatives to antibiotic growth promoters. The first study that evaluated the antibacterial activities of plant extracts was carried out in 1881; however, they started to be used as flavor enhancers only during the next decades. With the emergence of antibiotics in the 1950s, the use of plant extracts as antimicrobial agents almost disappeared. There are several studies in literature assessing the use of plant extracts, individually or in combination, as antimicrobials, antioxidants, or digestibility enhancers in animal feeds. Research results on the factors affecting their action, such as plant variety, harvest time, processing, extraction, as well as the technology employed to manufacture the commercial product and dietary inclusion levels show controversial results, warranting the need of further research and standardization for the effective use of plant extracts as performance enhancers, when added to animal feeds. This article aims at presenting plant extracts as alternatives to antibiotics, explaining their main modes of action as performance enhancers in broiler production.

EVALUATION OF DICLORAN`S CONTRIBUTION TO THE MUTAGENIC ACTIVITY OF CRISTAIS RIVER, BRAZIL, WATER SAMPLES

2,6-Dichloro-4-nitroaniline (dicloran) is a mutagenic aromatic amine used as an agricultural fungicide and in the synthesis of disperse dyes. It is a known mutagen (Salmonella/microsome assay) in strains TA98 and TA100. Dicloran was initially detected, but not quantified, in the Cristais River, Brazil. The objective of the present study was to estimate the contribution of dicloran to mutagenic activity in samples from this river. Dicloran was found in the raw water at 0.14 mu g/L but not in the treated water. Comparison of mutagenic potencies in Salmonella strain YG1041 for dicloran and the river water sample indicated that dicloran contributed less than 0.1% of total mutagenic activity.

Highs and lows

The past year has been a mixed one for research in the addictions. The Global Burden of Disease study confirmed that alcohol was a major contributor to the burden of disease in developed countries, as a risk factor for injury and alcohol dependence (Murray). A 10-year study of 65 171 Kaiser Permanente Medical Care Program members found that regular marijuana use had little impact on mortality (Sidney). Its association with increased AIDS mortality in men, probably suggests that it is a marker for male homosexual behaviour. Reassurance about the mortality risks of marijuana is premature because the mean age at follow-up was only 43 years: cigarette smoking and alcohol use were only modestly associated with premature mortality.