Host adaptation and specialization in Tetranychidae mites.

Composite generalist herbivores are comprised of host-adapted populations that retain the ability to shift hosts. The degree and overlap of mechanisms used by host-adapted generalist and specialist herbivores to overcome the same host plant defenses are largely unknown. Tetranychidae mites are exceptionally suited to address the relationship between host adaptation and specialization in herbivores as this group harbors closely related species with remarkably different host ranges-an extreme generalist the two-spotted spider mite (Tetranychus urticae Koch [Tu]) and the Solanaceous specialist Tetranychus evansi (Te). Here, we used tomato-adapted two-spotted spider mite (Tu-A) and Te populations to compare mechanisms underlying their host adaptation and specialization. We show that both mites attenuate induced tomato defenses, including protease inhibitors (PIs) that target mite cathepsin L digestive proteases. While Te solely relies on transcriptional attenuation of PI induction, Tu and Tu-A have elevated constitutive activity of cathepsin L proteases, making them less susceptible to plant anti-digestive proteins. Tu-A and Te also rely on detoxification of tomato constitutive defenses. Te uses esterase and P450 activities, while Tu-A depends on the activity of all major detoxification enzymatic classes to disarm tomato defensive compounds to a lesser extent. Thus, even though both Tu-A and Te use similar mechanisms to counteract tomato defenses, Te can better cope with them. This finding is congruent with the ecological and evolutionary times required to establish mite adaptation and specialization states, respectively.

Molecular identification and phylogenetic analysis of spider mites (Prostigmata: Tetranychidae) of Turkey.

The family Tetranychidae includes many agriculturally important species known as spider mites. Their morphological identification is quite difficult due to the tiny size of their taxonomic characters and the requirement for high-level expertise. This may lead to pest misidentification and thus failure in pest management. DNA-based species identification seems to offer an alternative solution to overcome these issues. In the present study, two common molecular markers-Cytochrome oxidase subunit I (COI) and Internal transcribed spacer 2 (ITS2)-were used to identify 10 spider mite species from Turkey. Furthermore, genetic distances for several of them were assessed. Panonychus ulmi and Bryobia kissophila had the lowest (1.1%) and highest (4.5%) intra-specific genetic distances, respectively. In addition, integrative taxonomy allowed to identify Eotetranychus quercicola in Turkey as a new record. The sequences herein obtained will allow rapid species identification using molecular techniques and will contribute to resolve the phylogenetic history of spider mites.

Spider mites (Acari: Tetranychidae) from the Black Sea Biosphere Reserve (Ukraine): faunistic survey, reinstatement of the genus Georgiobia Wainstein, 1960 and description of a new species.

Overall results of several spider mite surveys performed in the Black Sea Biosphere Reserve (Ukraine) during the 1990s to 2015 are presented. A total of 20 species were found, belonging to 11 genera, from 58 different host plant species, of which one mite genus, Mesobryobia (Wainstein, 1956), and three species, M. terpoghossiani (Bagdasarian, 1959), Georgiobia richteri (Bagdasarian, 1954) and Tetranychus lonicerae Beglyarov Mitrofanov, 1973, are new mite records to the Ukrainian acarofauna. Moreover, 15 new host plant species were also recorded as new hosts for 10 spider mite species. In addition, thanks to the newly collected material and a taxonomical historical review, and according to morphological data, we restore the genus Georgiobia Wainstein, 1960, and provide a new diagnosis of this genus. Therefore, a list of several new and reinstated combinations is provided. Finally, a new species, G. skuthiae n. sp., collected in the reserve on Agropyron sp., is described and illustrated, increasing the number of species that belong to the genus Georgiobia to nine.

Panonychus from Georgia: survey, taxonomical status and redescription of P. hadzhibejliae (Reck, 1947) (Acari, Tetranychidae).

A survey of Panonychus species was undertaken across Georgia from 2005 to 2014 on various host plants, revealing three species: Panonychus citri (McGregor, 1916), Panonychus hadzhibejliae (Reck, 1947) and Panonychus ulmi (Koch, 1836). New hosts for P. ulmi and P. citri are recorded, Buxus sempervirens, Hedera colchica and Prunus laurocerasus for P. ulmi and Ficus carica for P. citri, whereas P. hadzhibejliae was only found on F. carica. The newly collected material also allowed us to investigate the taxonomical status of P. hadzhibejliae. The comparison of P. hadzhibejliae with the two closely related species sampled in the survey, P. ulmi and P. citri, and with data of P. caricae found in the literature, shows that P. hadzhibejliae is a valid species. It can be separated from the three other Panonychus species without ambiguity especially using the female dorsal setae length in combination with the ratio between the length of the female dorsal opisthosomal f2 and h1 setae and the ratio between the palptarsal terminal eupathidium su and the related solenidion ω. A redescription of P. hadzhibejliae is provided including the male and some morphological characters, measurements and drawings of the female that were omitted in the original description. A key to the world species of Panonychus is also proposed.

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.

Tomato Whole Genome Transcriptional Response to Tetranychus urticae Identifies Divergence of Spider Mite-Induced Responses Between Tomato and Arabidopsis.

The two-spotted spider mite Tetranychus urticae is one of the most significant mite pests in agriculture, feeding on more than 1,100 plant hosts, including model plants Arabidopsis thaliana and tomato, Solanum lycopersicum. Here, we describe timecourse tomato transcriptional responses to spider mite feeding and compare them with Arabidopsis in order to determine conserved and divergent defense responses to this pest. To refine the involvement of jasmonic acid (JA) in mite-induced responses and to improve tomato Gene Ontology annotations, we analyzed transcriptional changes in the tomato JA-signaling mutant defenseless1 (def-1) upon JA treatment and spider mite herbivory. Overlay of differentially expressed genes (DEG) identified in def-1 onto those from the timecourse experiment established that JA controls expression of the majority of genes differentially regulated by herbivory. Comparison of defense responses between tomato and Arabidopsis highlighted 96 orthologous genes (of 2,133 DEG) that were recruited for defense against spider mites in both species. These genes, involved in biosynthesis of JA, phenylpropanoids, flavonoids, and terpenoids, represent the conserved core of induced defenses. The remaining tomato DEG support the establishment of tomato-specific defenses, indicating profound divergence of spider mite-induced responses between tomato and Arabidopsis.

Two new species of Bryobia (Acarina, Prostigmata, Tetranychidae) from South France.

Two new species of Tetranychidae belonging to the genus Bryobia are reported from France. Bryobiabelliloci sp. n. and Bryobiagigas sp. n. collected on Genistacinerea and Bituminariabituminosa, respectively, are described and illustrated in the present work. Additional data to the original description of Bryobiacinereae are given and an identification key to known Bryobia species from France is also provided.

New species and new records of Tetranychidae (Acarina, Prostigmata) from Thailand.

Sampling efforts conducted in several provinces from Thailand disclosed three new species of tetranychid mites. Two of them belong to the genus Tetranychus, namely Tetranychus occultaspina sp. nov. and Tetranychus truncatissimus sp. nov. and the third species belongs to the genus Schizotetranychus, Schizotetranychus krungthepensis sp. nov. They were collected on Ipomoea aquatica, Bambusa multiplex and Saccharum officinarum, respectively. New records and new hosts are also mentioned. 

Review of the invasion of Tetranychus evansi: biology, colonization pathways, potential expansion and prospects for biological control.

In the last two decades the subtropical red tomato spider mite, Tetranychus evansi, has expanded its geographical distribution and emerged as a major invasive agricultural pest. The mite is considered to be native to South America. Since its first report from north-eastern Brazil in 1952, it has been reported from different continents. This paper reviews literature on several aspects of the biology of T. evansi related to its status as an invasive species. It addresses taxonomical issues, occurrences, life history traits, host-plant interactions, genetic diversity of geographical isolates and worldwide colonisation pathways. It also presents updated data which allowed the assessment of the actual worldwide distribution of this species, from its discovery to the latest reports. As T. evansi is considered an emerging agricultural pest, we also present data based on modelling of the potential of T. evansi to colonize new geographical areas. In addition, this review presents past and current research on natural enemies of T. evansi potentially useful for its biological control. While summarizing the knowledge on T. evansi, the review emphasizes research possibilities that are worth pursuing, mainly concerning the ability of T. evansi to establish new populations and to detect new promising natural enemies.

Test of colonisation scenarios reveals complex invasion history of the red tomato spider mite Tetranychus evansi.

The spider mite Tetranychus evansi is an emerging pest of solanaceous crops worldwide. Like many other emerging pests, its small size, confusing taxonomy, complex history of associations with humans, and propensity to start new populations from small inocula, make the study of its invasion biology difficult. Here, we use recent developments in Approximate Bayesian Computation (ABC) and variation in multi-locus genetic markers to reconstruct the complex historical demography of this cryptic invasive pest. By distinguishing among multiple pathways and timing of introductions, we find evidence for the "bridgehead effect", in which one invasion serves as source for subsequent invasions. Tetranychus evansi populations in Europe and Africa resulted from at least three independent introductions from South America and involved mites from two distinct sources in Brazil, corresponding to highly divergent mitochondrial DNA lineages. Mites from southwest Brazil (BR-SW) colonized the African continent, and from there Europe through two pathways in a "bridgehead" type pattern. One pathway resulted in a widespread invasion, not only to Europe, but also to other regions in Africa, southern Europe and eastern Asia. The second pathway involved the mixture with a second introduction from BR-SW leading to an admixed population in southern Spain. Admixture was also detected between invasive populations in Portugal. A third introduction from the Brazilian Atlantic region resulted in only a limited invasion in Europe. This study illustrates that ABC methods can provide insights into, and distinguish among, complex invasion scenarios. These processes are critical not only in understanding the biology of invasions, but also in refining management strategies for invasive species. For example, while reported observations of the mite and outbreaks in the invaded areas were largely consistent with estimates of geographical expansion from the ABC approach, historical observations failed to recognize the complex pathways involved and the corresponding effects on genetic diversity.

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.

Immigration of phytoseiid mites from surrounding uncultivated areas into a newly planted vineyard.

This study reports (1) a faunistic survey of phytoseiid mites observed inside a vine plot and in neighbouring vegetation (other vine plots and uncultivated areas) and (2) dispersal of phytoseiid mites into the plot studied. These data aim to raise some hypotheses concerning natural colonisation of a vineyard by predatory mites. The study was carried out over 3 years (1999, 2000 and 2001) in an experimental plot planted with two cultivars (Grenache and Syrah) and with Sorbus domestica in a framework of agroforestry investigations. Phytoseiid mites were collected in both cultivated and uncultivated areas surrounding the experimental plot, and their dispersal into the plot studied using "aerial" traps. Densities remained quite low compared to previous studies. The main species encountered in the uncultivated areas and in the traps was Typhlodromus phialatus. Despite the low numbers of phytoseiid mites trapped, densities of phytoseiid mites into the vine field increased during 3 years. Typhlodromus phialatus, the species mainly found in the neighbouring uncultivated areas, was rarely found in vineyards. Another morphologically close species was predominant on vines: Typhlodromus exhilaratus. However, Kampimodromus aberrans the main phytoseiid mite species in vineyards of Southern France was not found in the present survey. Hypotheses for this colonisation process are discussed.

A genetic analysis of mancozeb resistance in Typhlodromus pyri (Acari: Phytoseiidae).

A field population of Typhlodromus pyri (Acari: Phytoseiidae) tolerant to mancozeb was selected in the laboratory. After 10 mancozeb selections the LC50 value for mancozeb was 73 times higher in the selected-10 strain compared to the standard susceptible strain. A genetic analysis using reciprocal crosses and backcrosses of female F1 progeny found no maternal effect. Resistance in the selected-10 strain was codominant in expression, dominance value was about -0.1. Backcrosses between F1 females and the susceptible strain indicate that the resistance to mancozeb could be principally conferred by a predominant gene, but additional factors would also be involved.

Side effects of mancozeb on Typhlodromus pyri (Acari: Phytoseiidae) in vineyards: results of multi-year field trials and a laboratory study.

The side effects of mancozeb on the predatory mite Typhlodromus pyri were studied in 4-year field trials on grapevine and in the laboratory. In the field, the effect of mancozeb varied according to previous mancozeb use. In vineyards where mancozeb had commonly been used over years, this fungicide is generally slightly toxic, in some cases moderately toxic and rarely toxic. In plots were mancozeb has never been used, its effect on T. pyri was more pronounced and varied from moderately toxic to toxic. Despite the toxicity of mancozeb, T. pyri populations have never been eradicated. Laboratory results obtained with the French CEB guideline no. 167 confirmed those of the 4-year field study: mancozeb was significantly more toxic to T. pyri populations collected in plots where it had rarely been used before the field experiment. In plots where mancozeb had been used for a long time, the susceptibility of T. pyri populations to this fungicide was reduced and female survival, fecundity but also viability of female progeny were less affected by mancozeb. Even though toxicity of mancozeb increased in controlled conditions, a significant correlation was established between field and laboratory results.

Variations in acaricidal effect of wettable sulfur on Tetranychus urticae (Acari:Tetranychidae): effect of temperature, humidity and life stage.

Under laboratory conditions, the acaricidal effect of wettable sulfur is influenced by climatic conditions and the stage of development of Tetranychus urticae. Its ovicidal effect results from the combined action of temperature and relative humidity (RH). Wettable sulfur becomes effective at 27.5 degrees C and 75% RH. Beyond this threshold, the acaricidal effect increases with rising temperature or humidity, to become complete at a temperature of 35 degrees C and 90% RH. Within the range of temperatures and humidities 20 degrees C/30% RH and 35 degrees C/90% RH the mortality of immatures (from protonymphs to teleiochrysalis) was total. Under similar experimental conditions, females usually died before the end of the experiment. Temperature and relative humidity increased the adulticidal potential of wettable sulfur. The fecundity of the sulfur-treated females and the viability of their progeny was found to depend on temperature and RH. According to the same climatic conditions, eggs were less susceptible than females, which were in turn less susceptible than juvenile stages.