The susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis

Over the last few years, several cases of feline leishmaniasis (FL) with cutaneous and visceral forms have been reported around the world. Nonetheless, the real susceptibility of cats to infection with Leishmania spp. and the outcome of leishmaniasis in these animals are poorly understood. Experimental studies on feline models will contribute to the knowledge of natural FL. Thus, in order to determine the susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis, 13 stray cats were infected with 10(7) promastigotes by the intradermal route in the ear and nose simultaneously and followed up for 72 weeks. Soon after infection, the earliest indication of a lesion was a papule on the ear at 2 weeks post-infection (w.p.i.). The emergence of satellite papules around the primary lesion was observed about 4 w.p.i. Two weeks later these papules coalesced and formed a huge and irregular nodule. Thereafter, there was lesion dissemination to the external and marginal surface of the ipsilateral ear, and later to the contralateral ear. At 10 w.p.i., some nodules became ulcerated. Nose lesions presented a similar evolution. At both sites, the largest lesion sizes occurred at 10 w.p.i. and started to decrease 15 days later. Ear and nose nodules healed at 32 and 40 w.p.i., respectively. Specific L. braziliensis IgG antibody titers (optical density> or = 0.01 as positive result) were detected as early as 2 w.p.i. (0.09 +/- 0.02) in only three animals (23%), and all cats had positive titers at 20 w.p.i. (0.34 +/- 0.06). Only three animals (38%) continued to show positive serology at 72 w.p.i. (0.08 +/- 0.02). Up to that time, none of the cats had lesion recurrence. In a feline model of cutaneous leishmaniasis, it seems that there is no correlation between active lesions and positive serology. The implications of these data are discussed.     

Sub-lethal effects of Beauveria bassiana (Balsamo) on field populations of the potato tuberworm Phthorimaea operculella Zeller in China

The potato tuberworm Phthorimaea operculella Zeller, is one of the most important potato pests worldwide including China. Several reports indicate that P. operculella could be controlled biologically by the use of beneficial fungus such as Beauveria bassiana(Bals.-Criv) Vuill. However, limited information is available under growing conditions in China. Thus, this study evaluated the sub-lethal effects of B. bassiana on the offspring of P. operculella by the age-stage, two-sex life table. First instar larva of P. operculella were treated with 1×107 conidia m L–1 of the fungus, and several biological parameters were evaluated. The fecundity, duration of the egg stage, all larval stages, pre-adult stage, and total pre-oviposition period, were significantly shorter than the control treatment. Offspring of treated parents, presented a net reproductive rate and mean generation time of 17.43 per day and 24.98 days, respectively, compared to 65.79 per day and 26.51 days for the untreated ones. This study provides basic information to help understanding the potential long-term effects of entomopathogenic fungi on P. operculella.     

Effect of spores of saprophytic fungi on phytoalexin accumulation in seeds of frog-eye leaf spot and stem canker-resistant and -susceptible soybean (Glycine max L.) cultivars

Two saprophytic fungi (Mucor ramosissimus and Rhizopus sp.) were tested for their ability to induce phytoalexin production by seeds of frog-eye leaf spot and stem canker-resistant and -susceptible soybean (Glycine max L.) cultivars. Only M. ramosissimus was shown to elicit a response and qualitative differences in phytoalexin accumulation were found between the susceptible and resistant cultivars. Glyceollins I, II, and III and glycinol were isolated from the susceptible cultivar, whereas Glyceollins I, II, and III, glycinol, glyceocarpin, genistein, isoformononetin, and N-acetyltyramine accumulated in the resistant cultivar in response to the same fungal elicitor. Genistein was found to be an inducibly formed isoflavonoid instead of a constitutive metabolite in the resistant cultivar, whereas N-acetyltyramine is described for the first time as a soybean phytoalexin. All the compounds, except genistein, showed fungitoxic activity against Cladosporium sphaerospermum. Spectral data of the pterocarpan phytoalexins, genistein, and N-acetyltyramine are also given in this work.     

In vitro effect of Aloe vera, Coriandrum sativum and Ricinus communis fractions on Leishmania infantum and on murine monocytic cells

In South America, visceral leishmaniasis is a zoonosis caused by the protozoan species Leishmania infantum (syn. L. chagasi) and is primarily transmitted through the bite of the female Lutzomyia longipalpis. Its main reservoir in urban areas is the dog. The application of control measures recommended by health agencies have not achieved significant results in reducing the incidence of human cases, and the lack of effective drugs to treat dogs resulted in the prohibition of this course of action in Brazil. Therefore, it is necessary to search new alternatives for the treatment of canine and human visceral leishmaniasis. The objectives of this study were to evaluate the in vitro effect of fractions from Aloe vera (aloe), Coriandrum sativum (coriander), and Ricinus communis (castor) on promastigotes and amastigotes of L. infantum and to analyze the toxicity against the murine monocytic cells RAW 264.7. To determine the viability of these substances on 50% parasites (IC50), we used a tetrazolium dye (MTT) colorimetric assay (bromide 3-4.5-dimethylthiazol-2-yl-2,5-dephenyltetrazolium), and on amastigotes we performed an in situ ELISA. All fractions were effective against L. infantum promastigotes and did not differ from the positive control pentamidine (p>0.05). However, the R. communis ethyl acetate and chloroform fractions, as well as the C. sativum methanol fraction, were the most effective against amastigotes and did not differ from the positive control amphotericin B (p>0.05). The R. communis ethyl acetate fraction was the least toxic, presenting 83.5% viability of RAW 264.7 cells, which was similar to the results obtained with amphotericin B (p>0.05). Based on these results, we intend to undertake in vivo studies with R. communis ethyl acetate fractions due the high effectiveness against amastigotes and promastigotes of L. infantum and the low cytotoxicity towards murine monocytic cells.     

First Report of Potato Psyllids, Bactericera cockerelli, Overwintering in the Pacific Northwest

Potato psyllids became a topic of interest at the end of the 2011 growing season in the Pacific Northwest when they were first documented to transmit ‘Candidatus Liberibacter solanacearum,’ the putative pathogen causing zebra chip disease in the region. Zebra Chip is characterized by above and below ground symptoms that cause significant yield loss. For many decades it has been unclear whether the potato psyllid migrates to states in the Pacific Northwest from large, well-documented infestation areas in California or Texas. Thus, we conducted a study in the spring of 2012 in the lower Columbia Basin (north east Oregon and south east Washington state), and in the fall, winter, and spring of 2012 in southwestern Idaho to determine if psyllids could be found overwintering. Potato psyllid was observed in November 2011 in southwestern Idaho and March 2012 in the lower Columbia Basin living on Solanum dulcamara L. (i.e., bittersweet nightshade), a perennial weed of wet habitats and riverbanks. Potato psyllids were collected and brought to the laboratory. Emerging adults from both locations (i.e., Columbia Basin and Idaho) were offered potato plants and they completed a second generation in approximately 15 days under similar environmental conditions. While overwinter survival of the potato psyllid in the Pacific Northwest is concerning for the potato industry, weather trends in the region were mild during the winter of 2012. It is unknown whether a colder or longer winter season would affect the overwintering biology we have observed. Observations through several coming winters are warranted.     

Screening of Iranian Potato Germplasm for Resistance to the Potato Tuberworm Phthorimaea operculella (Lepidoptera: Gelechiidae)

The potato tuberworm, Phthorimaea operculella (Zeller), is an important insect pest of potato, Solanum tuberosum L., both in storage and in the field. In this research, tubers of eight commercial potato cultivars and four Iranian selections with equal weight and dormancy were exposed to 10 pairs of adult P. operculella in a climate chamber set at 25?±?1 °C, 65?±?5 % RH and total darkness. In a free-choice situation, oviposition was lower on 397082–2, Khavaran and Morene compared to the other germplasm that were exposed to adults of P. operculella. Number of mines per tuber, length of mines per tuber, time of development of larvae, number of pre-pupae produced per tuber, weight of pre-pupae and number of eggs developed in ovaries per female were counted and/or measured on each commercial cultivar and selection. There were fewer and shorter mines on tubers of 397082–2, Khavaran and Morene compared to the other potato germplasm. The number of pre-pupae produced per tuber and the weight of pre-pupae were lower when P. operculella was reared on tubers of 397082–2, Khavaran and Morene. Also the development, survival and fecundity were lower when P. operculella was reared on those same germplasm. Flesh firmness was negatively correlated with larval survival (r ²?=?0.87); in addition, the percentage of starch and macronutrient composition was low on these three germplasm. Thus, tuber flesh firmness of these germplasm could delay larval penetration and lower establishment 397082–2, Khavaran and Morene showed promising traits that can be integral component of potato breeding for resistance to P. operculella and pest management programs.     

Cross-sectional serological study of canine Leishmania infection in Fortaleza, Ceará state, Brazil

Visceral leishmaniasis (VL) is one of the most important reemerging parasitic disease in the world. The domestic dog is the main reservoir in urban environments. The aim of this work was to extend the knowledge on canine Leishmania infection in the city of Fortaleza in northeastern Brazil, identifying the risk factors inherent in dog susceptibility to the infection. Two populations were analyzed, domestic dogs from clinics and the Veterinary Hospital Unit of Ceará State University and stray dogs captured by the Center for Zoonosis Control in Fortaleza. Blood samples were collected and centrifuged and the sera were stored at -20 degrees C. ELISA, with soluble crude Leishmania chagasi antigens (LTCC - WDCM731) was used for diagnosis. A total of 1,381 samples were tested, 750 from domestic and 631 from stray dogs. The seroprevalence of canine VL was 21.4% (135/631) in stray dogs and 26.2% (197/750) in domestic dogs. The seroprevalence of Leishmania infection in the six administrative regions of the city (Secretarias Executivas Regionais, or SER) among stray dogs was highest in SER V, representing 31.4% of the cases, with large dogs more infected (27.7%). Among domestic dogs Leishmania infection was most prevalent in SER V (38.5%) and VI (37.6%). The dogs' age (1-6 years), large size, environment with dense vegetation and presence of clinical signs compatible with Leishmania infection were associated with the illness in domestic dogs. The frequency of the infection varied seasonally. The seroprevalence was greatest in July and December. These results confirm Fortaleza is an endemic area for canine VL and suggest some variables associated with increasing infection risk in dog populations.     

Inorganic and organic phosphorus pools in earthworm casts (Glossoscolecidae) and a Brazilian rainforest Oxisol

We compared differences in soil phosphorus fractions between large earthworm casts (Family Glossoscolecidae) and surrounding soils, i.e., Oxisols in 10 year-old upland agroforestry system (AGR), pasture (PAS), and secondary forest (SEC) in the Central Brazilian Amazon. AGR and PAS both received low-input fertilization and SEC received no fertilization. We found that earthworm casts had higher levels of organic hydroxide P than surrounding soils, whereas fertilization increased inorganic hydroxide P. Inorganic P was increased by fertilization, and organic P was increased by earthworm gut passage and/or selection of ingested materials, which increased available P (sum of resin and bicarbonate fractions) and moderately available P (sum of hydroxide and dilute acid fractions), and P fertilizer application and land-use increased available P. The use of a modified sequential P fractionation produced fewer differences between earthworm casts and soils than were expected. We suggest the use of a condensed extraction procedure with three fractions (Available P, Moderately Available P, and Resistant P) that provide an ecologically based understanding of the P availability in soil. Earthworm casts were estimated to constitute 41.0, 38.2, and 26.0 kg ha⁻¹ of total available P stocks (sum of resin and bicarbonate fractions) in the agroforestry system, pasture, and secondary forest, respectively.     

Biological nitrogen fixation by common beans (<Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> L.) increases with bio-char additions

This study examines the potential, magnitude, and causes of enhanced biological N₂ fixation (BNF) by common beans (Phaseolus vulgaris L.) through bio-char additions (charcoal, biomass-derived black carbon). Bio-char was added at 0, 30, 60, and 90 g kg⁻¹ soil, and BNF was determined using the isotope dilution method after adding ¹⁵N-enriched ammonium sulfate to a Typic Haplustox cropped to a potentially nodulating bean variety (CIAT BAT 477) in comparison to its non-nodulating isoline (BAT 477NN), both inoculated with effective Rhizobium strains. The proportion of fixed N increased from 50% without bio-char additions to 72% with 90 g kg⁻¹ bio-char added. While total N derived from the atmosphere (NdfA) significantly increased by 49 and 78% with 30 and 60 g kg⁻¹ bio-char added to soil, respectively, NdfA decreased to 30% above the control with 90 g kg⁻¹ due to low total biomass production and N uptake. The primary reason for the higher BNF with bio-char additions was the greater B and Mo availability, whereas greater K, Ca, and P availability, as well as higher pH and lower N availability and Al saturation, may have contributed to a lesser extent. Enhanced mycorrhizal infections of roots were not found to contribute to better nutrient uptake and BNF. Bean yield increased by 46% and biomass production by 39% over the control at 90 and 60 g kg⁻¹ bio-char, respectively. However, biomass production and total N uptake decreased when bio-char applications were increased to 90 g kg⁻¹. Soil N uptake by N-fixing beans decreased by 14, 17, and 50% when 30, 60, and 90 g kg⁻¹ bio-char were added to soil, whereas the C/N ratios increased from 16 to 23.7, 28, and 35, respectively. Results demonstrate the potential of bio-char applications to improve N input into agroecosystems while pointing out the needs for long-term field studies to better understand the effects of bio-char on BNF.     

Factors regulating diversity and abundance of fish communities in Pantanal lagoons, Brazil

The factors effecting fish species richness, evenness and relative abundance in 19 floodplain lagoons in the Pantanal (Brazil) were examined. Richness and evenness were strongly correlated with the lagoon's: (i) isolation time from the main river; (ii) depth; and (iii) distance from the main river. Abundance of the five dominant fish species was correlated mainly with: (a) macrophyte cover; (b) the distance from the main river; and (c) piscivore abundance. These results suggest that the species select lagoons to avoid or minimize their confinement in inappropriate floodplain habitats. A combination of strategies, together with variations in the lagoon's connection period, determines the diversity and abundance of the fish species in the Nhecolândia Pantanal.