The Distribution of Cicadellinae Leafhoppers and Other Auchenorrhyncha on Coffee and Citrus in Puerto Rico.

Key words: : Caribovia coffeacola, Cicadellinae, coffee, Xylella fastidiosa.

Quantitative frame analysis and the annotation of GC-rich (and other) prokaryotic genomes. An application to Anaeromyxobacter dehalogenans.

MOTIVATION: Graphical representations of contrasts in GC usage among codon frame positions (frame analysis) provide evidence of genes missing from the annotations of prokaryotic genomes of high GC content but the qualitative approach of visual frame analysis prevents its applicability on a genomic scale. RESULTS: We developed two quantitative methods for the identification and statistical characterization in sequence regions of three-base periodicity (hits) associated with open reading frame structures. The methods were implemented in the N-Profile Analysis Computational Tool (NPACT), which highlights in graphical representations inconsistencies between newly identified ORFs and pre-existing annotations of coding-regions. We applied the NPACT procedures to two recently annotated strains of the deltaproteobacterium Anaeromyxobacter dehalogenans, identifying in both genomes numerous conserved ORFs not included in the published annotation of coding regions. AVAILABILITY AND IMPLEMENTATION: NPACT is available as a web-based service and for download at http://genome.ufl.edu/npact. CONTACT: lucianob@ufl.edu SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Influence of xylem fluid chemistry on planktonic growth, biofilm formation and aggregation of Xylella fastidiosa.

Xylella fastidiosa is the causal agent of Pierce's disease in grapevines. The mechanisms of pathogenicity are largely due to occlusion of xylem vessels by aggregation of X. fastidiosa and biofilm formation. Xylella fastidiosa was subjected to xylem fluids with varying chemistries to examine the effects of nutritional components on bacterial growth in vitro. The exposure of X. fastidiosa to xylem fluids collected from different Vitis genotypes resulted in highly significant differences in both planktonic growth and biofilm formation. Planktonic growth of X. fastidiosa in Vitis xylem fluid was correlated to the concentration of citric acid, amino acids (glutamic acid, glutamine, histidine, valine, methionine, isoleucine and phenylalanine) and inorganic ions (copper, magnesium, phosphorus and zinc). Biofilm formation was correlated to many amino acids at 1 h of incubation. Xylem fluid from Vitis rotundifolia cv. Noble (fluid that supported low planktonic growth) was supplemented with the compounds that were correlated above to levels found in Vitis champinii cv. Ramsey (fluid that supported high planktonic growth) to determine the direct impact of xylem constituents on the growth characteristics of X. fastidiosa. Augmentation of fluid from Noble with the amino acids listed above, citric acid, calcium and magnesium resulted in increased planktonic growth and aggregation.

Preference-performance linkage of the xylem feeding leafhopper, Homalodisca vitripennis (Hemiptera Cicadellidae).

Insect species exhibiting a weak linkage between adult preference and immature performance have frequently been shown to be prone to outbreaks. We used choice and no-choice tests to examine the preference-performance linkage of the xylem fluid-feeding leafhopper, Homalodisca vitripennis Germar. Leafhoppers were offered a choice of hosts common to their native range and also a choice from hosts where they have been recently introduced. Behavior (residence preference, oviposition preference, and consumption rates) was quantified in choice tests. Performance (development of immature leafhoppers, fecundity, body weights, and survivorship) was quantified in no-choice tests. Virtually all aspects of leafhopper behavior and performance varied with host species, yet there were no linkages between adult preference and immature performance. Lagerstroemia indica and Citrus sinensis were the preferred hosts, but both species supported <30% of neonate development until the second stadia. Glycine max was the superior developmental host with development to the adult stage exceeding 40%, but this host was seldom used by adult leafhoppers. Adult preference reflected aspects of adult performance including increases in fecundity, body weights, and survivorship. These preference-performance linkages were impacted by environmental context, insect reproductive status, and insect feeding history. Essential amino acids were consistently correlated with performance of both adult and developing insects; relationships between nutrients and preference were less consistent. The weak linkage of adult preference and immature leafhopper performance are discussed in terms of outbreaks of H. vitripennis.