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

ABSTRACT: 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.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.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.

SUBMITTER: Saune L

PROVIDER: S-EPMC4470001 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Project description:Environmental factors like temperature have a great impact on the predation potential of biological control agents. In the present study, the functional response of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae) to the pest mite Tetranychus urticae (Acari: Tetranychidae) at moderate to high temperatures under laboratory conditions was determined. The study aimed to understand the prey-predator interaction under different temperatures and prey densities. Five constant temperatures (24 °C, 27 °C, 30 °C, 33 °C, and 36 °C), and thirteen prey densities (4, 5, 8, 10, 12, 15, 16, 20, 24, 25, 30, 32, and 40) of each stage (adult, nymph, larvae, and egg stage) were employed in the experiment. Observations were made 24 h after the start of each experiment. Results revealed that the predatory mites showed type II functional response to adult females of T. urticae, whereas type I to other stages (nymphs, larvae, and eggs) of T. urticae. The predation capability of adult predatory mites on T. urticae was significant at 24-36 °C. The instantaneous attack rate (a) of N. californicus increased and the handling time (Th) decreased with an increase in temperature. The maximum attack rate was recorded at 36 °C (1.28) for the egg stage. The longest handling time was (0.78) for the larval stage of T. urticae at 30 °C. Daily consumption increased with increasing prey density. Maximum daily consumption was observed at 33 °C (30.00) at the prey density of 40. Searching efficiency decreased with the increase in prey density but was found to increase with the rise in temperature. N. californicus was found to be voracious on the larval and egg stages. Conclusively, the incorporation of N. californicus at earlier stages (larvae and eggs) of T. urticae would be beneficial under warm conditions because managing a pest at its initial stage will save the crop from major losses. The results presented in this study at various temperatures will be helpful in different areas with different temperature extremes. The results of the functional response can also be applied to mass rearing, quality testing, and integrated pest management programmes.

Project description:Soybean is one of the most important sources of food, protein, and oil in the world. Reductions in grain number and quality are caused by different biotic stresses. One of the most common is the phytophagous mite Tetranychus urticae Koch (Acari: Tetranychidae), which inhibits plant growth and grain production. The identification of plant responses to early and late T. urticae infestation is important for a better understanding of the mite-plant interaction. We therefore aimed to evaluate the physiological and molecular responses of soybean plants to mite infestation for 5 and 21 days. Visual and microscopic symptoms of leaf damage, H2O2 accumulation, and lipid peroxidation increased consistently throughout the infestation period, while shoot length/dry weight, chlorophyll level, and number of days to reach specific developmental stages were negatively affected by T. urticae infestation. Using proteomic analysis, we identified 185 and 266 differentially abundant proteins after early (5 days) and late (21 days) mite infestation, respectively, which suggests a complex remodeling of diverse metabolic pathways. GO, KEGG, and protein-protein interaction analyses indicated that photorespiration, chlorophyll synthesis, amino acid metabolism, Krebs cycle/energy production, mitochondrial translation, nucleotide salvage, PS II assembly, and reductive pentose-P cycle are all impacted after both early and late infestation. Specific metabolic pathways modified only after early infestation include cell wall modification, cytoskeleton composition, cell division, and lysine/histidine metabolism, while JA biosynthesis, antioxidant system, S-adenosyl methionine cycle, PS II repair, cysteine/methionine/glutathione/ascorbate/-linolenic acid/selenocompound metabolism, arginine biosynthesis, and proteasome are modified only after late infestation. These differentially abundant proteins can be used as biotechnological tools in future breeding programs aiming at increased resistance to mite infestation.

Project description:Many species are shifting their distributions due to climate change and to increasing international trade that allows dispersal of individuals across the globe. In the case of agricultural pests, such range shifts may heavily impact agriculture. Species distribution modelling may help to predict potential changes in pest distributions. However, these modelling strategies are subject to large uncertainties coming from different sources. Here we used the case of the tomato red spider mite (Tetranychus evansi), an invasive pest that affects some of the most important agricultural crops worldwide, to show how uncertainty may affect forecasts of the potential range of the species. We explored three aspects of uncertainty: (1) species prevalence; (2) modelling method; and (3) variability in environmental responses between mites belonging to two invasive clades of T. evansi. Consensus techniques were used to forecast the potential range of the species under current and two different climate change scenarios for 2080, and variance between model projections were mapped to identify regions of high uncertainty. We revealed large predictive variations linked to all factors, although prevalence had a greater influence than the statistical model once the best modelling strategies were selected. The major areas threatened under current conditions include tropical countries in South America and Africa, and temperate regions in North America, the Mediterranean basin and Australia. Under future scenarios, the threat shifts towards northern Europe and some other temperate regions in the Americas, whereas tropical regions in Africa present a reduced risk. Analysis of niche overlap suggests that the current differential distribution of mites of the two clades of T. evansi can be partially attributed to environmental niche differentiation. Overall this study shows how consensus strategies and analysis of niche overlap can be used jointly to draw conclusions on invasive threat considering different sources of uncertainty in species distribution modelling.

Dataset Information

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

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