Detection of Bemisia tabaci Mediterranean cryptic species on soybean in São Paulo and Paraná States (Brazil) and interaction of cowpea mild mottle virus with whiteflies

Since the detection of Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) species in Brazil in the early 1990s, this whitefly has been the predominant species and the main viral vector in the country. In this work, whiteflies were collected from commercial soybean fields near and far from greenhouses where Mediterranean (MED) species had previously been detected infesting vegetable crops. Results indicated that MEAM1 was the predominant whitefly species in soybean in most sampling sites, while MED was found colonizing soybean plants in open field conditions alone and/or with MEAM1 in several places. Among the tested insects, MED species was mostly detected harbouring the facultative endosymbiont Hamiltonella. We also detected cowpea mild mottle virus (CPMMV) infecting soybean plants. Transmission assays demonstrated that MED species was more efficient transmitting CPMMV from beans to beans and from soybean to soybean plants than MEAM1, while MEAM1 was more efficient in transmitting the virus from soybean to bean than MED. Performance assays indicated that adult emergence of both species on CPMMV-infected soybean plants was higher when compared with the emergence on healthy plants. Moreover, nonviruliferous MED and MEAM1 adults preferred to settle more often on healthy plants, while viruliferous adults settled more often on CPMMV-infected soybean plants. As MED has already been found in soybean open fields in São Paulo and Paraná States, Brazil, and it is a good vector of CPMMV, we anticipate problems related to whitefly management and to increase in the incidence of the virus in soybean.     

Vaccination strategies with oral booster for surubim hybrid (Pseudoplatystoma corruscans × P. reticulatum) against haemorrhagic septicaemia

This study evaluated the efficiency of differently prepared vaccines against Aeromonas hydrophila in the hybrid surubim (Pseudoplatystoma corruscans × P. reticulatum). Survival and haemato‐immunological parameters were compared between the treatments: non‐vaccinated fish (C); bacterin‐vaccinated fish (B); bacterin plus oral booster vaccinated fish (B+O); bacterin and toxoid‐vaccinated fish (B+T) and bacterin, toxoid and oral booster‐vaccinated fish (B+T+O). Fourteen‐days vaccinated fish from B+O and B+T+O were fed with an oral booster for 4 days. After 1 week, the fish were intraperitoneally challenged with 2 × 10⁸ CFU mL^?1 of A. hydrophila. Fish from the treatment B+T+O showed the lowest cumulative mortality (11.36%) 96 h after challenge, compared with other treatments (22.72–44.04%), and a relative survival of 74%. Serum immunoglobulin in B+T+O fish was higher than in other treatments. All vaccinated fish showed an increased agglutination titre when compared with non‐vaccinated fish, both before and after challenge. Fish fed with oral booster showed an increase in phagocytic percentage before and after challenge. It can be inferred that the oral booster vaccination was efficient in reducing mortality in hybrid surubim by enhancing the response against haemorrhagic septicaemia due to A. hydrophila infection.     

Hematological and splenic Doppler ultrasonographic changes in dogs sedated with acepromazine or xylazine

Objective

To evaluate the onset and duration of hematological changes and the use of Doppler ultrasound (spleen) in dogs sedated with acepromazine or xylazine.

Seasonal evolution of water status after outplanting of two provenances of Holm oak nursery seedlings

Forest restoration programs using Holm oak (Quercus ilex ssp. ballota [Desf.] Samp.) have had limited success. The effect of plant provenance on plantation success is uncertain, although some previous studies suggest that some provenances may be better able to tolerate stress. We studied the tolerance to drought in seedlings from two Spanish provenances of Holm oak before and after outplanting. One provenance was from a continental climate with cold winters (GR) and the other was from a xeric climate (HU). Seedlings were subjected to a water stress test in the nursery during the summer and survival was visually assessed after 2?weeks. In addition, 35 healthy seedlings of each provenance that were not subjected to the water stress tests were used for outplanting experiment. In these plants the seasonal changes in water potential at dawn (Ψ), specific leaf area (SLA), cuticular transpiration (E_c), and loss of xylem hydraulic conductance of twigs (PLC) were measured over 18?months. After the water stress test in summer, mortality was 44.3?% for GR seedlings and 12.6?% for HU seedlings. In addition there were differences between the two provenances in plant water status after planting. The HU provenance had a better water status and was more water conservative in the summer (higher Ψ, lower E_c, lower PLC), but not in the winter. The different drought tolerance and water relations parameters of these two provenances indicate that provenance should be considered in forest restoration and conservation programs involving Holm oak.     

Riparian coverage affects diets of characids in neotropical streams

Abstract – Aquatic ecosystems are influenced by the surrounding terrestrial environment. This work studied the influence of vegetation of riparian zones on the feeding patterns of two nektonic characids, Astyanax paranae and Bryconamericus iheringii, in a basin surrounded by an agricultural area. Nine streams within the Corumbataí River basin (São Paulo State, Brazil) with varying proportions of adjacent riparian forest (RF) and pastures were set apart in three arbitrary categories: Riparian Forest (>90% RF), Mixed Coverage (banks covered by 30–60% RF; MC) and Pasture (<29% RF, PA); resident characids were sampled in the dry and rainy seasons and evaluated in regard to composition of diets. Astyanax paranae fed on allochthonous food sources in RF and MC, and on autochthonous food sources on PA streams; B. iheringii fed on autochthonous food sources in RF streams and in mixed resources (detritus and sediment) in PA streams. Selection of food source was related to, and altered by, stream channel structure and composition of substratum. Preservation and restoration of native riparian vegetation is key to preservation of resident characids in small streams of this river basin.     

Comparative study of genetic diversity of Clavibacter michiganensis subsp. michiganensis isolates from the Canary Islands by RAPD-PCR, BOX-PCR and AFLP

Molecular characterization of seedborne pathogens is an important issue when discerning their origin and tracking the spread of a disease. In the Canary Islands (Spain), Clavibacter michiganensis subsp. michiganensis (Cmm) was first detected in 2002, causing severe losses in many tomato-growing areas. Fifty four strains of this bacterium isolated from 2002 to 2007 and 19 strains from different countries were characterized for genetic diversity. RAPD-PCR, BOX-PCR and AFLP provided differentiation among Cmm strains whereas no differences were observed with ERIC-PCR, REP-PCR and 16S-23S ITS PCR-RFLP. RAPD-PCR and BOX-PCR revealed high homogeneity among the Canary Island strains (>80 and >75% of similarity, respectively) which could not be grouped based on tomato cultivar, location or year of isolation. By contrast, strains of Cmm from other countries displayed high diversity, providing several clusters, most of which were composed of a single strain. Similarly, AFLP analysis of 29 selected strains of Cmm gave the same profile for the Canarian ones (>90% of similarity) whereas high polymorphism was obtained with strains from different countries. Moreover, two strains, one from the USA and another from Spain, were related to the Canarian strains, according to RAPD-PCR (>60% of similarity), BOX-PCR (>75%) and AFLP analysis (>90%), suggesting a common origin. The circumstances under which the Cmm outbreaks occurred in the Canary Islands and the high homogeneity observed among the Canarian strains would suggest that the bacterium was introduced into the region from only one origin.     

Tissue‐print and squash real‐time PCR for direct detection of ‘Candidatus Liberibacter’ species in citrus plants and psyllid vectors

Huanglongbing (HLB) disease is seriously threatening and/or damaging the citrus industry worldwide. Accurate detection of the three species associated with HLB disease, ‘Candidatus Liberibacter asiaticus’, ‘Candidatus Liberibacter africanus’ and ‘Candidatus Liberibacter americanus’, is essential for the preventive control of the disease. Real‐time PCR is a useful tool for bacterial detection. However, nucleic acid purification steps limit the number of samples that can be processed by PCR. Universal detection of ‘Ca. Liberibacter’ species was achieved by direct tissue‐printing and spotting of plant leaf petiole extracts or squashing of individual psyllids onto paper or nylon membranes. Primers were designed and used with TaqMan chemistry for accurate detection of the bacterium in immobilized targets (prints of 10 overlapping leaf pedicels per tree, or squashed single vectors), by extraction with water and direct use for real‐time PCR. This simplified method was validated and could detect HLB‐liberibacters in 100% of leaves with symptoms and 59% of symptomless leaves collected from HLB‐infected trees. The use of direct assays as template showed good agreement with use of purified DNA (κ = 0·76 ± 0·052). The squash assay allowed detection of the bacterium in 40% of mature Diaphorina citri that fed on leaves of HLB‐infected trees with or without symptoms. A commercial ready‐made kit based on this technology showed 96% accuracy in intra‐laboratory performance studies. The simplified direct methods of sample preparation presented herein can be effectively adopted for use in rapid screening of HLB agents in extensive surveys, certification schemes or for epidemiological and research studies.     

Chemical quality of leachates and enzymatic activities in Technosols with gossan and sulfide wastes from the São Domingos mine

Journal of Soils and Sediments - São Domingos mine area (Portuguese Iberian Pyrite Belt) contains several mine wastes with different environmental hazard which are disposed irregularly over a...     

Effects of rapid global warming at the Paleocene-Eocene boundary on neotropical vegetation

Temperatures in tropical regions are estimated to have increased by 3° to 5°C, compared with Late Paleocene values, during the Paleocene-Eocene Thermal Maximum (PETM, 56.3 million years ago) event. We investigated the tropical forest response to this rapid warming by evaluating the palynological record of three stratigraphic sections in eastern Colombia and western Venezuela. We observed a rapid and distinct increase in plant diversity and origination rates, with a set of new taxa, mostly angiosperms, added to the existing stock of low-diversity Paleocene flora. There is no evidence for enhanced aridity in the northern Neotropics. The tropical rainforest was able to persist under elevated temperatures and high levels of atmospheric carbon dioxide, in contrast to speculations that tropical ecosystems were severely compromised by heat stress.