Western blot analysis of the humoral response of dogs experimentally infected with Angiostrongylus vasorum (Baillet, 1866)

Seven cross-bred dogs were inoculated with Angiostrongylus vasorum and serum samples were analyzed using the enzyme-linked immunosorbent assay (ELISA) and Western blot (WB). ELISA detected specific antibodies anti-A. vasorum, from 14 to 28 days after inoculation (DAI) and persisted throughout the experiment. Using WB, the main antigens detected had molecular weight of approximately 115, 102, 86, 76, 69, 56, 41, 32, 28, 20-22 and 10kDa.     

Cover Image,Volume 75, Issue 3

The front cover image is based on the Research Artice Effects of exogenous methyl jasmonate and salicylic acid on rice resistance to Oebalus pugnax by Thais F Stella de Freitas et al., DOI: 10.1002/ps.5174 . Image Credit: Thais Fernanda Stella de Freitas, Federal University of Rio Grande do Sul.

     

Bidirectional colonization and biofilm formation by Erwinia psidii in eucalypt plants

Dieback and wilt caused by Erwinia psidii is an emerging disease that has been causing considerable damage in eucalypt plantations. Because it is a recently emerged disease, several aspects of the bacterial interaction with its host still remain to be elucidated. In this work, we studied the E. psidii colonization and biofilm formation in eucalypt tissues by specific detection using PCR and scanning electron microscopy (SEM). The results indicate that the bacterium is able to translocate in stem tissue mainly acropetally, although movement in the basipetal direction was also observed to a lesser extent, always through the xylem. No colonization of phloem tissues was observed. In addition to colonizing the xylem, E. psidii colonized the parenchymatous tissue. The bacterium formed cell aggregates enveloped by fibrillar material that evolved into complex, well-structured biofilms in stem and leaf tissues. In contrast, no biofilm formation was observed on abiotic surfaces. These observations suggest that biofilm formation plays an important role in the elicitation of dieback and wilt symptoms caused by E. psidii on eucalypt plants. This study not only shows ultrastructural aspects of the E. psidii communities but also tissue damage in eucalypt plants that was associated with the presence of bacterial aggregates and formation of tyloses.     

Study of Biodegradation Processes of BTEX-ethanol Mixture in Tropical Soil

In Brazil, gasoline is currently blended with ethanol and both compounds may contaminate the environment when spills occur. Ethanol preferential biodegradation delays gasoline degradation in the aquifer, as previously observed; in unsaturated soil a delayed recovery of culturable bacteria and removal of residues in the presence of ethanol suggest a similar situation. This study monitors microbial degrading activity in unsaturated soil with BTEX and BTEX-ethanol mixtures under tropical conditions as well as the effects of bioventing on contaminants degradation. Enzymatic activity was quantified by measuring fluorescein-diacetate hydrolysis by microorganisms, which determines total degrading activity in soil. As microbial enhanced activity may alter soil electromagnetic properties, soil dielectric constant shifts were monitored using Time Domain Reflectometry (TDR), while chemical analyses evaluated contamination residues throughout the experiment. Results suggest that ethanol delays BTEX biodegradation and that bioventing may compensate for this delay by providing oxygen for the continuation of microbial activity. Contamination and bioventing stimulated soil microbiota, while culturable populations were inhibited by contamination, showing soil toxicity. The presence of ethanol caused a higher and longer-lasting boost in enzymatic activity; TDR measurements did not follow these activity shifts, proving not to be an adequate tool for evaluating microbial activity in these experimental conditions. Residual BTEX were detected only in ethanol-containing non-ventilated soils after contamination. The set of results suggests that ethanol could delay BTEX degradation because of its constitutive degradation by soil microbiota, but this effect may be bypassed by bioventing.     

Integrated Soybean Pest Management in Micro River Basins in Brazil

A Soybean IPM system was deployed in large, continuous river basin areas. The system was designed to improve the productivity of the rural environment by restoring balance among pests and their natural enemies. The system was developed with the active participation of various governmental, industrial and academic institutions, and it was based on the main approaches utilized by the EMBRAPA soybean IPM program referred here as IPM-Soybean.The work of IPM-Soybean in microbasins is being implemented in five counties in Paraná state (Campo Mourão, Mamborê, Missal, Cambé and Toledo) in an area of approximately 18,020ha of soybean involving 343 producers at various stages of implementation. The results obtained in the Rio do Campo basin in Campo Mourão, after four years of IPM-Soybean, showed drastic changes in pest control practices. Mean number of insecticide applications per cropping year in the river basin fell from 2.8 (1993/94 season) to 1.23 four seasons later. Biological control of the velvetbean caterpillar, Anticarsia gemmatalis, by Baculovirus anticarsia increased 57%, from 205ha treated with this biological product in the 1993/94 season to 2730ha in 1998. A mean of about 300,000 Trissolcus basalis (Wollaston) adults were released per year to control soybean stink bugs. As a consequence of the parasitoid release and the use of more selective insecticides, the number of insecticide applications to control stink bugs was significantly reduced. After two soybean seasons with IPM-Soybean in the river basin, mean applications for stink bugs decreased from 0.81 before the program started to 0.09 in 1996. The mean number of applications in the region and the state respectively were 9.20 and 11.44 times greater. In 1997 and 1998, the results again showed very low population densities of stink bugs in the river basin area, with a consequent reduction in insecticide applications for the control of these pests. Furthermore there was a substantial improvement in the range of products used in this area for soybean pest control. Broad spectrum products, used in 97.5% of the applications before start of IPM-Soybean (1993/94), were replaced with more selective products, especially biologicals and growth regulators. The latter had rarely been used by the river basin producers before the study (0.6% of the applications), but they accounted for 35.8% of the applications after four seasons with IPM-Soybean. IPM-Soybean developed in river basins has resulted in a more stable control system that, in turn, provides greater long-term equilibrium between the pests and the natural enemies populations in these soybean producing areas.     

Aggressiveness,cultural characteristics and genetic variation of Ceratocystis fimbriata on Eucalyptus spp.

Ceratocystis wilt caused by Ceratocystis fimbriata is currently one of the most important diseases affecting Eucalyptus in Brazil. This disease is controlled by planting resistant clones; however, possible variability in the pathogen population may compromise the selection of resistant genotypes. Therefore, this study aimed to evaluate the aggressiveness of C. fimbriata isolates obtained from Eucalyptus spp, as well as their cultural characteristics and genetic variation of their ITS rDNA gene region. We found a significant isolate × clone interaction, with the isolate RM35 being the most aggressive and presenting a broader spectrum of aggressiveness, causing greater xylem discoloration on a larger number of clones. This isolate is the most suitable for artificial inoculations focusing on the selection of resistant materials. Clones CLR‐236 and CLR‐212 were identified as the most resistant and clones CLR‐223 and CLR‐240 as the most susceptible and those that are recommended as reliable comparators in artificial inoculations. All isolates were morphologically similar and differed from C. fimbriata from sweet potato by the formation of a wide mouth endoconidiophore that produces doliform endoconidia. According to the culture media and temperature applied, the most favourable conditions for mycelial growth were observed using malt extract agar (MEA) and temperatures ranging from 24 to 26°C. There was no correlation between sporulation and aggressiveness. Great variation in ITS sequences was observed, and a total of five ITS genotypes were identified among the ten isolates tested.     

Wilt and die‐back of Eucalyptus spp. caused by Erwinia psidii in Brazil

A new disease of unknown bacterial aetiology has been observed in eucalyptus stands since 2009. It is characterized by die‐back, wilting and lesions on the branches, petiole and midrib in association with macroscopic and microscopic bacterial ooze. To date, this disease has been observed in stands of clonal Eucalyptus saligna, E. grandis and E. urophylla x E. grandis hybrids and in E. dunnii seedling plantations in the states of São Paulo, Rio Grande do Sul and Mato Grosso do Sul. Considering the economic importance of eucalyptus plantations and the potential losses caused by this disease, this study aimed to identify and characterize the causal agent. Thirty‐four strains were obtained from infected plants, which were collected in the field from four locations. The inoculation of detached leaves and intact rooted cuttings supported pathogenicity in eucalyptus. The phylogenetic analysis of four housekeeping genes (16S rDNA, gapA, recA and rpoB) as well as biochemical tests confirmed the identity of strains belonging to the species Erwinia psidii. This is the first report of E. psidii as the cause of wilt and die‐back in Eucalyptus spp. in Brazil.     

Supervised independent component analysis as an alternative method for genomic selection in pigs

The objective of this work was to evaluate the efficiency of the supervised independent component regression (SICR) method for the estimation of genomic values and the SNP marker effects for boar taint and carcass traits in pigs. The methods were evaluated via the agreement between the predicted genetic values and the corrected phenotypes observed by cross‐validation. These values were also compared with other methods generally used for the same purposes, such as RR‐BLUP, SPCR, SPLS, ICR, PCR and PLS. The SICR method was found to have the most accurate prediction values.     

Sexual Precocity of Nellore Bulls that are Offspring of Super Precocious,Precocious and Normal Cows in Extensive Farming Conditions

The objective of this work was to verify that mothers classified as super precocious (M1) and precocious (M2) produce more precocious bulls than females classified as normal (M3). This study included 21 186 animals with an average age of 21.29 ± 1.77 months that underwent a breeding soundness evaluation from 1999 to 2008. Of these animals, 2019, 6059 and 13 108 were offspring of M1, M2 and M3 females, respectively. In the breeding soundness examination, the animals were classified as sound for reproduction, sound under a natural mating regime, unsound for reproduction and discarded. To compare the averages obtained for each category of mother within the individual breeding soundness classes, a chi‐square test with a 5% error probability was used, considering the effects of year and month of birth and farm. For the three classes of mothers (M1, M2 and M3), 67.26, 67.22 and 64.16% of bull calves were considered sound for reproduction and 19.71, 19.46 and 21.90% were considered unsound for reproduction, respectively. There was no difference in the frequency of animals that were sound for reproduction under the natural breeding regime between the three classes of mothers (8.87, 9.31 and 9.19%, respectively). There was a difference between the numbers of precocious and normal females that were discarded, with frequencies of 4.01 and 4.75%, respectively (p < 0.05). There were differences in year and month of birth and farm between super precocious and precocious cows in relation to the breeding soundness classification of the animals. It was concluded that the bull offspring of super precocious and precocious cows presented a higher percentage of approval in the breeding soundness examination than the bull offspring of normal cows, demonstrating that the selection for precocity of females has contributed to an increase in the sexual precocity of the herd in relation to the sexual maturity of bulls.