<Emphasis Type="Italic">Asaia</Emphasis> symbionts interfere with infection by Flavescence dorée phytoplasma in leafhoppers

The transmission of microbial pathogens by insect vectors can be affected by the insect’s microbial symbionts, which may compete in colonizing organs, express antagonistic factors or activate host immune response. Acetic acid bacteria of the genus Asaia are symbionts of the leafhopper Scaphoideus titanus, which transmits Flavescence dorée phytoplasma. These bacteria could be used as control agents against the disease. Here, we experimentally investigated the interaction between different strains of Asaia and phytoplasma transmission in the laboratory by using the model leafhopper Euscelidius variegatus and the plant host Vicia faba. We found that uncultivable and low concentrations of Asaia phylotypes were associated with E. variegatus. When we supplied different Asaia strains isolated from other insects and exhibiting different phenotypes to E. variegatus orally, the bacteria stably colonized the leafhopper, reached relatively higher densities and could then be isolated from the host. We conducted transmission trials of Flavescence dorée phytoplasma with individuals colonized with three exogenous Asaia strains. When the phytoplasma became established in the bodies of E. variegatus, leafhoppers were able to transmit it to broad beans, with transmission rates ranging from 33 to 76% in different experiments. However, leafhoppers that were colonized by one of the Asaia strains producing an air–liquid interface biofilm exhibited significantly reduced phytoplasma acquisition, with infection rates at 5–28%, whereas they were 25–77% in control insects. Although the mechanisms regulating this interference remain to be elucidated, our results provide evidence of the potential use of Asaia as a biocontrol agent.     

A three-year longitudinal study on the effects of a diet containing genetically modified Bt176 maize on the health status and performance of sheep

This study shows that a diet including insect-resistant Bt176 maize, fed to 53 ewes and their progeny for 3 years, did not have adverse effects on their health or performance and that no horizontal gene transfer to ruminal microorganisms or animal tissues was detected. No differences were observed regarding performance, reproductive traits, haematological parameters, antioxidant defences, lymphocyte proliferative capacity, phagocytosis and intracellular killing of macrophages, and ruminal microbial population characteristics between control and genetically modified (GM) maize-fed animals. Immune response to Salmonella abortus ovis vaccination was more efficient in GM maize fed sheep. No modifications of histological features of tissues were found; however, cytochemical analyses of ruminal epithelium by Ki67 staining provided evidence of proliferative activation of basal cells in all GM maize-fed ewes. Preliminary electron microscopy analyses of the liver and pancreas revealed smaller cell nuclei containing increased amounts of heterochromatin and perichromatin granules in GM maize-fed lambs. Meat protein content and water loss by cooking were slightly affected by the dietary treatment. No transgenic DNA was detected in tissues, blood, and ruminal fluid or ruminal bacteria. Longitudinal studies should be included in evaluation of food safety whenever possible and sheep may be a useful animal model for toxicological assessment.     

Plant-derived essential oils affecting settlement and oviposition of Bemisia tabaci (Genn.) biotype B on tomato

The silverleaf whitefly Bemisia tabaci (Genn.) biotype B (Hemiptera: Aleyrodidae) is an economically important pest of tomatoes Solanum lycopersicum (L.), causing irregular ripening on fruits and transmitting several plant pathogenic geminiviruses. The management of this pest is commonly based on repetitive spraying with synthetic pesticides, causing serious environmental damages and increase of resistance by insect population. In the present study, essential oils from the leaves of Artemisia camphorata Vill., Ageratum conyzoides L., Foeniculum vulgare Mill., Lippia alba (Mill.) N. E. Br., Plectranthus neochilus Schltr., and Tagetes erecta L. were investigated for their possible repellent and oviposition-deterrent effects against B. tabaci biotype B on tomato. In a multi-choice assay, P. neochilus essential oil was the most active repellent and oviposition deterrent. Essential oils of A. conyzoides and T. erecta significantly deterred the female B. tabaci biotype B from laying eggs on treated tomato leaflets compared with the control. (E)-Caryophyllene (30.67 %) and the monoterpenes α-pinene (15.02 %) and α-thujene (11.70 %) were identified as the major constituents of the essential oil of P. neochilus. Our findings demonstrated the potential of essential oil of P. neochilus and other oils in the reduction of settlement and oviposition of B. tabaci biotype B on tomato.     

Detection of Neospora caninum in an aborted goat foetus

In Italy Neospora caninum has been reported in cattle, in buffaloes and in dogs. No data are available about the infection in sheep and goats. In this paper, the authors report the detection of protozoan cysts, identified as N. caninum by PCR, in the brain of an aborted goat foetus.     

Production and quality of bovine oocytes and embryos

Many factors influence the efficiency of the in vitro embryo production technology in cattle but the most important are the physiological conditions of the donor and the culture protocols for oocyte maturation and fertilization and for embryo culture from zygote to blastocyst. Therefore, general factors such as age, body conditions and herd management play a pivotal role together with more specific factors such as reproductive soundness and ovarian cyclicity. Given that good quality and competent oocytes are available a complex series of processes, including oocyte maturation, fertilization and culture of the derived zygotes, must be completed to generate viable embryos.     

Incidence of ‘Candidatus Liberibacter europaeus’ and phytoplasmas in Cacopsylla species (Hemiptera: Psyllidae) and their host/shelter plants

Psyllids, as vectors of phloem-restricted plant pathogens, are serious agricultural pests. Fruit tree phytoplasmas are transmitted by different Cacopsylla spp., while other psyllids are known vectors of liberibacters. Recently, the bacterium ??Candidatus Liberibacter europaeus?? was found in pear trees and in Cacopsylla pyri (Linnaeus), the vector of ??Ca. Phytoplasma pyri??. This new species does not cause symptoms in plants and is probably a symbiont rather than a pathogen. Based on these findings and the assumption that ??Ca. Liberibacter europaeus?? is widespread, we studied its distribution in the genus Cacopsylla and in the respective host and shelter plants (where psyllids aestivate and overwinter), as well as its possible co-presence with ??Ca. Phytoplasma?? spp. We tested 14 Cacopsylla species and 11 plant species from northwestern Italy, Hungary and Israel, characterized by warm oceanic, temperate continental and warm Mediterranean climatic conditions, respectively. ??Ca. Liberibacter europaeus?? was common within the Cacopsylla genus, being present in nine of the 14 species screened as well as in most host plants, whereas none of the shelter plants tested positive for this bacterium. Altogether, these findings indicate the presence of ??Ca. Liberibacter europaeus?? in continental zones, whereas it does not seem to be widespread in the Mediterranean region. Furthermore, lack of specific symptoms in all infected plants confirms an endophytic relationship with this bacterium, while its abundance in insects suggests a beneficial role for the host. Co-infections with phytoplasmas, observed in insects and plants, require further study to evaluate the possible interactions between them.     

Hypoglicemic effect of Leandra lacunosa in normal and alloxan-induced diabetic rats

Leandra lacunosa, popularly known as "erva-do-jabuti", is used in Brazilian folkloric medicine for the treatment of diabetes mellitus. Based on this traditional indication, the aim of this work was to evaluate the hypoglycemic activity of the hydroalcoholic extract of L. lacunosa aerial parts (LLH) in normal and alloxan-induced diabetic rats. Chromatographic fractionation of LLH was also carried out by several techniques, affording isolation of the following major compounds: ursolic acid (1), kaempferol (2), luteolin (3), and quercetin (4). The oral administration of LLH (500 mg/kg) in normal rats caused a significant reduction of 24.7% (P<0.05) in the blood glucose levels after 2 h of treatment, while the administration of chlorpropamide (20 mg/kg, p.o.) led to a reduction of 40.2% (P<0.01). After oral administration of glucose (10 g/kg, p.o.), LLH (500 mg/kg, p.o.) significantly inhibited the increase in blood glucose levels compared with the negative control group. The oral treatment with LLH (500 mg/kg) in alloxan-induced diabetic rats significantly reduced the blood glucose levels in 47.8% after 4 h of treatment, while chlorpropamide resulted in a significant reduction of 71.7% in the 4th hour. Our results showed that LLH, displays hypoglycemic activity, which may be related to the effect of the major compounds identified in the crude extract. This study seems to provide biological evidence for the folkloric use of L. lacunosa in the treatment of diabetes mellitus.