Nutrient flux associated with the emergence of Quesada gigas Olivier (Hemiptera: Cicadidae) in an urban ecosystem.

Large-bodied arthropods, such as cicadas, can be able to reallocate significant amounts of nutrients during adult emergence. Evidence suggests that Quesada gigas Olivier emergence constitutes an important nutrient flux from belowground to aboveground. The purpose of this study was to estimate the amount of nitrogen, proteins, and lipids resulting from the emergence of Q. gigas in an urban ecosystem in Central Brazil. Adult specimens captured from September to November 2006 were weighed and submitted to biochemical analysis. Population density was approximately 4,200 individuals per hectare. Mean individual dry mass was 1.03 g and contained 12.6% proteins, 8.4% lipids, and 5% nitrogen. Total biomass input from the species was 4.3 kg ha(-1) y(-1), with a consequent annual reallocation of approximately 545 g of proteins, 363 g of lipids, and 216 g of nitrogen per hectare. The data obtained suggest that Q. gigas emergence can cause significant translocation of nutrients from belowground to aboveground, and is therefore an important biological event for ecosystem function.

Characterization of atypical Erwinia carotovora strains causing blackleg of potato in Brazil.

AIMS: To determine the characteristics of bacteria associated with the blackleg disease of potato in Brazil and compare them with species and subspecies of pectolytic Erwinia. METHODS AND RESULTS: Biochemical and physiological characteristics of 16 strains from blackleg-infected potatoes in State of Rio Grande do Sul, Brazil, were determined and differentiated them from all the E. carotovora subspecies and E. chrysanthemi. Pathogenicity and maceration ability of the Brazilian strains were greater than those of E. carotovora subsp. atroseptica, the causal agent of potato blackleg in temperate zones. Analyses of serological reaction and fatty acid composition confirmed that the Brazilian strains differed from E. carotovora subsp. atroseptica, but the sequence of 16S rDNA gene and the 16S-23S intergenic spacer (IGS) region confirmed the Brazilian strains as pectolytic Erwinia. Restriction analysis of the IGS region differentiated the Brazilian strains from the subspecies of E. carotovora and from E. chrysanthemi. A unique SexAI restriction site in the IGS region was used as the basis for a primer to specifically amplify DNA from the Brazilian potato blackleg bacterium in PCR. CONCLUSIONS: The bacterium that causes the blackleg disease of potato in Brazil differs from E. carotovora subsp. atroseptica, the blackleg pathogen in temperate zones. It also differs from other subspecies of E. carotovora and from E. chrysanthemi and warrants status as a new subspecies, which would be appropriately named E. carotovora subsp. brasiliensis. SIGNIFICANCE AND IMPACT OF THE STUDY: The blackleg disease of potato is caused by a different strain of pectolytic Erwinia in Brazil than in temperate potato-growing regions. The Brazilian strain is more virulent than E. carotovora subsp. atroseptica, the usual causal agent of potato blackleg.