Isolation, characterization and PCR multiplexing of microsatellite loci for a mite crop pest, Tetranychus urticae (Acari: Tetranychidae).

BACKGROUND: Tetranychus urticae is a highly polyphagous species with a cosmopolitan distribution that has the status of pest in more than 100 economically significant crops all over the world. Despite a number of previous efforts to isolate genetic markers, only a reduced set of microsatellite loci has been published. Taking advantage of the whole genome sequence of T. urticae that recently became available; we isolated and characterized a new set of microsatellite loci and tested the level of polymorphism across populations originating from a wide geographical area. RESULTS: A total of 42 microsatellite sequences widespread in the T. urticae genome were identified, the exact position in the genome recorded, and PCR amplification of microsatellite loci tested with primers defined here. Fourteen loci showed unambiguous genotype patterns and were further characterized. Three multiplex polymerase chain reaction sets were optimized in order to genotype a total of 24 polymorphic loci, including 10 previously published Tetranychus-specific loci. The microsatellite kits successfully amplified 686 individuals from 60 field populations for which we assessed the level of genetic diversity. The number of alleles per locus ranged from 3 to 16 and the expected heterozygosity values ranged from 0.12 to 0.81. Most of the loci displayed a significant excess of homozygous and did not model the Hardy-Weinberg equilibrium. This can be explained by the arrhenotokous mode of reproduction of T. urticae. CONCLUSIONS: These primers represent a valuable resource for robust studies on the genetic structure, dispersal and population biology of T. urticae, that can be used in managing this destructive agricultural pest.

Perineural ultrasound-guided catheter bacterial colonization: a prospective evaluation in 747 cases.

BACKGROUND AND OBJECTIVES: Ultrasound guidance is increasingly used for catheter insertion and could make it more complicated to guarantee aseptic insertion of catheters. The current study evaluated the incidence of colonization of ultrasound-guided perineural catheter (US-PNC) placed for postoperative analgesia. METHODS: We evaluated prospectively for 14 months 760 ultrasound-guided catheters in a single center placed under sterile conditions. Quantitative culture of all the catheters was performed after withdrawal. Colonization was defined as ≥10(3) colony-forming units/mL. Infection was defined as the isolation of the same microorganism from the colonized catheter and from blood culture and/or culture of an abscess. Univariate and multivariate logistic regression analyses were performed to determine the independent risk factors of US-PNC colonization. RESULTS: Incidences of colonization and infections were 10.4% (95% confidence interval [95% CI], 8.2%-14.4%) and 0.13% (95% CI, 0%-3.8%), respectively, in a total of 747 catheters. Coagulase-negative staphylococci colonization was documented in 69% of the colonized catheters. Local inflammation was more frequently noted when catheters were colonized (26.9% [95% CI, 15.2%-38.7%] versus 8.1% [95% CI, 4.2%-11.9%], P = 0.005). Independent factors for ultrasound-guided catheter colonization were duration of catheter placement more than 48 hours (odds ratio [OR], 4.9; 95% CI, 1.1-12.7; P = 0.003), diabetes (OR, 2.3; 95% CI, 1.4-9.6; P = 0.004), and antibiotic administration during the month preceding surgery (OR, 1.8; 95% CI, 1.5-7.8; P = 0.01). CONCLUSIONS: Although infection rate is low, there is a risk of ultrasound-guided catheter colonization that deserves careful monitoring of the insertion site in the postoperative period.

A critical review on some closely related species of Tetranychus sensu stricto (Acari: Tetranychidae) in the public DNA sequences databases.

Taxonomic misidentification of the specimens used to obtain DNA sequences is a growing problem reported for different groups of organisms, which threatens the utility of the deposited sequences in public DNA databases. This paper provides new evidence of misidentifications in molecular DNA public databases in phytophagous mites of the Tetranychidae family belonging to the group Tetranychus (Tetranychus). Several species in this group are of economic and quarantine importance in agriculture and among them Tetranychus urticae, a highly polyphagous mite causing outbreaks in many crops worldwide, is certainly the most studied. We analyzed and evaluated the identity of 105 GenBank accessions of ITS2 rDNA and 138 COI mtDNA sequences which were deposited as T. urticae and those of 14 other taxa morphologically closely related to Tetranychus sensu stricto. In addition, ITS2 and COI sequences of 18 T. urticae samples collected for this study and identified by morphological criteria, were generated and included in the analyzed dataset. Among the deposited sequences in the GenBank database, numerous cases of apparently mistaken identities were identified in the group Tetranychus s. str., especially between T. urticae, T. cinnabarinus, T. kanzawai and T. truncatus. Unreliable sequences (misidentified or dubious) were estimated at nearly 30%. In particular the analysis supports the invalidity of the controversial species status of T. cinnabarinus. More generally, it highlights the need of using combined morphological and molecular approaches to guarantee solid species diagnostics for reliable sequence accessions in public databases.

Suitability of two laboratory testing methods to evaluate the side effects of pesticides on Typhlodromus pyri Scheuten (Acari: Phytoseiidae).

BACKGROUND: Laboratory results of the French ANPP/CEB guideline No. 167 and IOBC/WPRS Ring Testing Group methods for testing the side effects of pesticides on the predatory mite Typhlodromus pyri Scheuten were compared with respect to their suitability to evaluate the toxicity of three pesticides. RESULTS: Results obtained with the ANPP/CEB guideline allow the demonstration of significant differences between two slightly toxic products, a dichlofluanid 500 g kg(-1) kWP (Euparen) 50WP) and a quinoxyfen 250 g L(-1) SCC (Legend), and a highly toxic cymoxanil 60/mancozeb 200/folpet 275 g kg(-1) WP [Remiltine F Pepite) (RFP)], on the basis of bioassays conducted in the laboratory. In contrast, results obtained with the IOBC/WPRS method classified all three as harmful. CONCLUSION: The evaluation of the toxicity of RFP revealed that the concentration, the quantity of the wet deposit and the food source used in the IOBC/WPRS method maximise the toxicity, in comparison with those used in the ANPP/CEB protocol. Valid criteria in controls were all respected in the ANPP/CEB tests but not in the IOBC/WPRS samples. This result revealed difficulties related to the use of the IOBC/WPRS method in laboratories.