Advertisement
Browse Subject Areas
?

Click through the PLOS taxonomy to find articles in your field.

For more information about PLOS Subject Areas, click here.

  • Loading metrics

Analysis of Genetic Variation in Brevipalpus yothersi (Acari: Tenuipalpidae) Populations from Four Species of Citrus Host Plants

Analysis of Genetic Variation in Brevipalpus yothersi (Acari: Tenuipalpidae) Populations from Four Species of Citrus Host Plants

  • Delfina Salinas-Vargas, 
  • Ma. Teresa Santillán-Galicia, 
  • Ariel W. Guzmán-Franco, 
  • Antonio Hernández-López, 
  • Laura D. Ortega-Arenas, 
  • Gustavo Mora-Aguilera
PLOS
x

Abstract

We studied species diversity and genetic variation among populations of Brevipalpus mites from four species of citrus host plants. We sampled mites on orange, lime, grapefruit and mandarin trees from orchards at six localities distributed in the five most important citrus producing states in Mexico. Genetic variation among citrus host plants and localities were assessed by analysis of nucleotide sequence data from fragments of the mitochondrial cytochrome oxidase subunit I (COI). Both Brevipalpus yothersi and B. californicus were found at these sites, and B. yothersi was the most abundant species found on all citrus species and in all localities sampled. B. californicus was found mainly on orange and mandarin and only in two of the states sampled. AMOVA and haplotype network analyses revealed no correlation between B. yothersi genetic population structure and geographical origin or citrus host plant species. Considering that a previous study reported greater genetic diversity in B. yothersi populations from Brazil than we observed in Mexico, we discuss the possibility that the Mexican populations may have originated in the southern region of America.

Introduction

Brevipalpus Donnadieu is the most economically important mite genus within the family Tenuipalpidae [1]. Brevipalpus contains more than 300 species that have a worldwide distribution [2, 3]. Brevipalpus mites are commonly parthenogenetic (females producing females) and males are only rarely found in some species [4]. Most Brevipalpus species are economically important because they feed on agricultural crops and some of them also transmit viruses to host plants, including Citrus sinensis (L.) Osbeck [57], Coffea arabica L. (Gentianales: Rubiaceae) [8], Passiflora edulis Sims (Malpighiales: Passifloraceae) [9, 10] and some ornamental species in the genera Angraecum, Diplocaulobium, Stanhopea, Miltonia, Hormidium [11, 12], Xylobium, Oncidium, Trichopilia [13] and Cymbidium [14]. Brevipalpus phoenicis s.l. Geijskes, Brevipalpus californicus Banks, and Brevipalpus obovatus Donnadieu are considered amongst the most important agricultural pests and all are virus vectors [15, 16].

Beard et al. [17] described the existence of morphospecies within B. phoenicis; however, these morphospecies have been recently elevated to full species status [18]. Using molecular techniques, Sanchez-Velazquez et al. [19] successfully identified the existence of two of these newly-described species in Mexico: Brevipalpus yothersi (Baker), which was the most abundant species, and Brevipalpus papayensis (Baker). Brevipalpus californicus was also recorded but at very low densities. Even though 22 samples were collected in Brazil, a comparison of the population genetic structure of B. yothersi from Mexico and Brazil showed that 14 haplotypes were observed in Brazilain populations while only four haplotypes were identified in the 37 samples from Mexico [19]. A diversity of factors are thought to influence genetic variation amongst populations of mites including geographical distance and population density. Low population densities can lead to habitat fragmentation and limited gene flow [2022]. However, adaptation to host plants by herbivorous arthropods can also play a major role in their differential genetic structure or even lead to speciation [23].

The main difference between samples from Mexico and Brazil was that the mites from Brazil were collected from five different varieties of orange, while all the samples from Mexico were collected from the same variety of orange [19]. We hypothesized that the greater genetic diversity found in Brazilian populations compared with Mexican populations was due to the diversity of host plants from which they were sampled. Based on this, and using a fragment of the mitochondrial gene cytochrome oxidase subunit I (COI), we determined the genetic population structure of B. yothersi collected from four different citrus species from five of the most important citrus-producing areas in Mexico.

Materials and Methods

Host plants and sample collection

Mites were collected from four different citrus species: sweet orange (C. sinensis), grapefruit (Citrus paradisi Macfad.), mandarin (Citrus reticulata Blanco) and lime (Citrus latifolia (Yu. Tanaka) Tanaka). Sample collections were made in the municipalities of Culiacan and Guasave in Sinaloa, Mugica in Michoacan, Montemorelos in Nuevo León, Oxkutzcab in Yucatan and Martinez de la Torre in Veracruz. The locations were selected because they all had orchards containing the four citrus species under evaluation, except Veracruz where no grapefruit could be found. The study was conducted in private orchards with the permission of the landowners. The field studies did not involve endangered or protected species.

The sampling methodology was similar for all citrus species. Mites were collected from both fruits and leaves from five trees with evident signs of mite feeding damage. In the field, and with the aid of a stereomicroscope, only the female adults of Brevipalpus species were collected for transportation to the laboratory. These female mites were inoculated on to fruits of the same species from the same orchard that had been prepared as described below. Each fruit was washed with soapy water, rinsed and allowed to dry for 12 hours. Half of each fruit was immersed in liquid wax which was allowed to solidify, and a thin line (approx. 2 mm width) of insect barrier glue (Agralan Ltd, Ashton Keynes. Wiltshire, UK) was placed around each orange, separating the wax-covered half from the clean half. Three lines (3 cm long × 2 mm width) made from a mixture of sand, flour and plaster in equal proportions were placed on the clean half of each orange (without wax) to provide refuges and oviposition sites for the mites. Approximately 10–50 adult female mites were collected and introduced on to each fruit. Once the mites had been introduced, each prepared fruit was then placed inside a plastic container (13 x 12 x 8 cm) on a layer of expanded polystyrene foam (2 cm thick). The wax-covered section of the fruit was embedded in the polystyrene layer to prevent the fruit from moving inside the container during transportation to the laboratory. Twenty-five fruits were prepared for each citrus × location combination resulting in a total of 575 fruits. No grapefruit could be found in Veracruz.

In the laboratory, one adult female was randomly selected from each fruit and placed on to a different fruit of the same citrus species that had been prepared as described previously. All fruits, each bearing a single female adult mite, were placed individually inside plastic containers and incubated at 25 ± 2°C, 60% RH and 12:12 light: dark regime. Fruits were replaced when necessary if dehydration was evident. Fruits were maintained under these conditions until the first generation of adult mites had developed.

Species diversity and analysis of the effect of host plant species on the genetic population structure of Brevipalpus species

DNA extraction and PCR protocols.

Genomic DNA was extracted from two first-generation adult mites per fruit, each representing an experimental sample. For this, the DNeasy Blood & Tissue (QIAGEN, Germantown, MD, USA) kit was used following the manufacturer’s instructions. A fragment of the gene COI was amplified using the primers DNF (TGA TTT TTT GGT CAC CCA GAA G) and DNR (TAC AGC TCC TAT AGA TAA AAC) [24]. PCR reactions were done in a 25 μL reaction volume containing 2.5 μL of buffer 10X (600 mM Tris-SO4 (pH 8.9), 180 mM ammonium sulphate), 1 mM of MgCl2, 0.2 μM of each primer, 0.2 mM of dNTP’s, 0.5 μL of Taq DNA polymerase (Quiagen, GmbH, Hilden, Germany) and 5 μL (approx. 20 ng) of DNA. PCR amplifications were done using a MyCycler (BIO-RAD Laboratories Inc., Hercules, CA, USA). Thermal conditions used were as follows: one cycle of 4 min at 94°C, followed by 35 cycles of 60 s at 94°C, 60 s at 54°C and 60 s at 72°C with a final extension at 72°C for 5 min. PCR products were visualized on 1% agarose gels in 1X TAE. GelPilot 100 bp Plus (QIAGEN, GmbH, Hilden, Germany) size markers were used. The gels were stained with ethidium bromide (0.1 μg mL–1) and photographed. All PCR products were sent to the company Macrogen Inc. (South Korea) for direct sequencing.

Data analysis.

Sequence traces were edited and assembled using BioEdit v.7.1.9 [25]. Multiple alignments were made using Clustal W [26] implemented in BioEdit using the default alignment parameters set in the program. All sequences were analysed using maximum likelihood in Molecular Evolutionary Genetic Analysis (MEGA) ver. 6.0 for Windows, with the Close-Neighbour-Interchange algorithm [27]. The robustness of branches was estimated by bootstrap analysis with 1000 repeated samplings of the data [28]. Tree reconstruction was made excluding non-synonymous substitutions, without any effect on tree topology. We show the tree including all sites. For the taxonomic placement of the samples, additional sequences from different Brevipalpus species were retrieved from GenBank. The sequence from Cenopalpus pulcher (Canestrini and Fanzago) (Acari: Tenuipalpidae) was retrieved from GenBank and used as the outgroup for this analysis. In addition, the Nei-Gojobori method [29], as implemented in the Z test in the program MEGA 6.0 [27], was used to compute the synonymous and nonsynonymous distances at a 5% significance level.

Genetic differences amongst haplotypes within each Brevipalpus species sampled were detected in a maximum parsimony network [30] using TCS v. 1.21 [31]. The connection limit amongst haplotypes (limits of parsimony) was set to the default value of 95%, and where gaps were treated as a 5th state. For the following analyses, only the samples from B. yothersi, the most abundant species after the phylogenetic analysis (see results section), were used. The partition of genetic variation amongst host citrus species populations and amongst populations from different geographical origins were analysed separately, and each analysis was followed by a comparison amongst all populations by analysis of molecular variance (AMOVA), estimated by computing F-statistics using Arlequin v. 3.5 [32] with 10000 permutations. In addition, the Mantel test was conducted to assess the correlation between genetic and geographic distances using the Isolation by Distance (IBD) web service [33].

Results

Species diversity in the genus Brevipalpus

One hundred and sixty sequences were obtained in total. After alignment and trimming, all sequences were truncated to 362 bp for B. yothersi and to 427 bp for B. californicus. Sequences contained 329 non-variables sites, 98 variable sites and 53 sites with parsimonious information. The phylogenetic analysis showed the existence of only two species of Brevipalpus in the samples, B. yothersi (131 samples, S1 Table) and B. californicus (29 samples, S2 Table). These Brevipalpus species were clearly separated from each other by bootstrap values above 90% (Fig 1).

thumbnail
Fig 1. Dendogram inferred from maximum likelihood analysis of COI data from B. yothersi and B. californicus.

The first letter (or two letters) in each sample name represents the Mexican state from which mite samples were collected: Sinaloa (S), Michoacan (M), Veracruz (V), Nuevo Leon (NL) and Yucatan (Y). Different colours represent different citrus species from which mite samples were collected: orange (N), mandarin (M), grapefruit (T) and lime (L). Other Brevipalpus species used as reference species and Cenopalpus pulcher (Canestrini and Fanzago) (Acari: Tenuipalpidae) used as the outgroup, are labelled according to their GenBank accession numbers. Only bootstrap values above 90% were considered.

https://doi.org/10.1371/journal.pone.0164552.g001

Genetic variation amongst B. yothersi populations

Haplotype network analysis revealed the existence of 11 haplotypes (Fig 2A). The most common haplotype was H04 with 65 samples of which ten were from orange, 23 from mandarin, 20 from grapefruit and 12 from lime. The second most abundant haplotype was H01 with 45 samples of which 12 were from orange, 12 from mandarin, 5 from grapefruit and 16 from lime. Haplotype H10 contained 13 samples, of which three were from orange, four from mandarin, one from grapefruit and five from lime. Haplotypes H02, H03, H05, H06, H07, H08 and H09 contained only one sample each. AMOVA analysis showed that only 5.9% of the variation could be explained by the host plant species from which the mites were collected, while 94.1% of the variation was explained by comparisons amongst samples regardless of the host plant species (Table 1). When the effect of geographical origin was analysed, 44.5% of the variation could be explained by geographical origin and 55.45% could be explained by the variation amongst populations regardless of geographical origin. Although the effect of geographical separation after AMOVA analysis showed a 44.55% contribution for the overall genetic variation, Mantel tests on pairwise genetic and geographic distances did not show a significant isolation by distance (IBD) pattern (r = 0.2141, P = 0.7810) (Fig 3).

thumbnail
Fig 2.

Most parsimonious haplotype network for the 11 haplotypes found in B. yothersi (A) and the three haplotypes found in B. californicus (B). Haplotypes are connected with a 95% confidence limit. Each line in the network represents a single mutational change. Small white circles indicate missing haplotypes. Numbers of samples per haplotype are shown in parentheses.

https://doi.org/10.1371/journal.pone.0164552.g002

thumbnail
Fig 3. Mantel test graph.

The graph shows the correlation between genetic variation (based on COI sequence data) and distance (Km) found in B. yothersi populations.

https://doi.org/10.1371/journal.pone.0164552.g003

thumbnail
Table 1. Results of the analyses of molecular variance (AMOVA) of COI sequences from B. yothersi collected from four different citrus species from five localities.

All tests were based on both molecular distances and haplotype frequencies. Statistical significance: P<0.001 (**) and NS = not significant.

https://doi.org/10.1371/journal.pone.0164552.t001

Genetic variation amongst B. californicus populations

Haplotype network analysis revealed the existence of three haplotypes (Fig 2B). The most common haplotype was H2 containing 26 samples, of which 13 were from orange, seven from mandarin, three from grapefruit and three from lime. Haplotype H3 contained two samples, one from mandarin and one from lime, and haplotype H1 included one sample from mandarin.

Discussion

Our results confirm the presence of B. yothersi in orchards from the five Mexican states where samples were collected. Brevipalpus californicus was only found in Nuevo Leon and Veracruz consistent with earlier observations [34, 19]. Our haplotype analysis revealed 11 haplotypes in B. yothersi populations. This represents a greater number of haplotypes compared with the study of Sanchez-Velazquez et al. [19] who only reported four haplotypes for Mexico. However, our results showed that there was no significant correlation between haplotype diversity and the citrus species from which the mites were collected. The different number of haplotypes reported by Sanchez-Velazquez et al. [19] compared to the present study could be related to the number of samples analysed, as those authors analysed 37 sequences obtained from B. yothersi, compared with our study where we used 131 sequences from the same mite species. Interestingly, limited samples of mites from Brazil (only 22 samples) still showed a greater genetic diversity, with 14 haplotypes, compared with either our current study or the study of Sanchez-Velazquez et al. [19] of Mexican samples. Furthermore, the AMOVA analysis showed insignificant variation in haplotype diversity due to host plant species, ruling out the potential existence of host associated differentiation (HAD) in B. yothersi populations.

HAD in herbivores can be found at different taxonomic levels of the host. For example, amongst individual plants of the same species [35], different populations within the same plant species [36] or amongst different plant species [37]. HAD has been reported previously for B. phoenicis s.l. mites collected from orange, hibiscus (Hibiscus rosa-sinensis L.) (Malvales: Malvaceae) and acerola (Malpighia glabra L.) (Malpighiales: Malpighiaceae); when populations from each of these hosts plants were transferred on to a different host plant species they failed to reproduce suggesting a close adaptation to the original host plant [38]. It is likely that HAD could still be detected in B. yothersi populations if mites had been collected from plant species from different genera or families rather than just different species within the same genus. For example, B. yothersi has been reported on other hosts such as coconut, Cocos nucifera L. (Arecales: Arecaceae); sunflower, Helianthus annuus L. (Asterales: Asteraceae) and avocado, Persea americana Mill. (Laurales: Lauraceae) [17], although not evaluated here these populations may be different from the populations on citrus.

It is possible that the Mexican B. yothersi populations could have originated from the Brazilian populations. It is assumed that, if greater genetic variation is found in a particular region, that this region could be considered as the potential place of origin, from where only a few haplotypes successfully adapt and migrate into other regions [39]. A preliminary haplotype analysis using Brazilian sequences from B. yothersi obtained by Sanchez-Velazquez et al. [19] (data not shown) and sequences obtained in our current study showed that from the 14 haplotypes obtained from the Brazilian samples, two were also found in our Mexican samples, partially confirming our hypothesis that the origin of the Mexican B. yothersi populations was Brazil. In addition, as reported by Groot et al. [38], B. phoenicis s.l. can be host specific, failing to reproduce on alternate hosts, which could lead to local extinction of haplotypes and reduced genetic variation.

We found more B. yothersi compared with B. californicus. This result was similar to previous reports for Mexico [34, 19] and suggests that B. yothersi could be more successful in colonizing different citrus species in different regions compared with B. californicus. Brevipalpus yothersi was collected from all citrus species and regions, whereas B. californicus was only found in two Mexican states (Nuevo Leon and Veracruz) and mainly on orange and mandarin. When we were rearing through the first generation adults for DNA extraction, most of the field B. californicus adults that were placed on individual fruits failed to reproduce, which significantly reduced the number of samples we could analyse. It is possible that B. californicus has another preferred host, which was not studied here, but certainly warrants further investigation.

The forces influencing observed levels of genetic diversity in B. yothersi, while unrelated to host plant use (Table 1), could be partially attributed to the different control strategies carried out in each region. Although the use of acaricides is the most common control method, the frequency and type of acaricide may vary amongst regions. Indeed, the effect of the control methods used against herbivore populations and its relationship with their genetic population structure has been reported previously. Populations of Tetranychus urticae Koch (Trombidiformes: Tetranychidae) in mandarin orchards showed higher genetic diversity when mites were collected in orchards under an integrated pest management (IPM) program compared with mites collected in orchards under organic management (OM) [40]. These authors suggest that the alternation of some acaricides used in the IPM orchards could be responsible for the different population genetics observed.

In conclusion, B. yothersi was found on all citrus species and in all regions sampled. Brevipalpus californicus were only found in two regions and mostly on orange and mandarin. Genetic variation in B. yothersi populations was not related to host plant use or geographical origin. Considering that greater genetic variation in B. yothersi populations from Brazil compared with Mexico has been reported previously, we suggest that the Mexican populations may have originated from this southern region of America.

Supporting Information

S1 Table. List of samples of Brevipalpus yothersi.

GenBank accession numbers, locality and haplotype assignment after the haplotype network analysis are provided. List of sequences used as a reference for the genetic comparison are shown. SL = Sinaloa, MN = Michoacan, VZ = Veracruz, NL = Nuevo Leon, YN = Yucatan.

https://doi.org/10.1371/journal.pone.0164552.s001

(DOC)

S2 Table. List of samples of Brevipalpus californicus obtained from different host plant species.

GenBank accession numbers, locality and haplotype assignment after the haplotype network analysis are provided. List of sequences used as a reference for the genetic comparison are shown. VZ = Veracruz, NL = Nuevo Leon, YN = Yucatan.

https://doi.org/10.1371/journal.pone.0164552.s002

(DOC)

Acknowledgments

DSV received a scholarship from CONACYT-Mexico. We thank the Crop Protection Committees from the states of Sinaloa, Michoacan, Veracruz, Nuevo Leon and Yucatan for their valuable help during mite collection in the field. No conflict of interest declared by the authors.

Author Contributions

  1. Conceptualization: DSV MTSG AWGF AHL LDOA GMA.
  2. Formal analysis: DSV MTSG AWGF AHL.
  3. Funding acquisition: MTSG GMA.
  4. Investigation: DSV MTSG.
  5. Methodology: DSV MTSG AWGF AHL LDOA GMA.
  6. Project administration: MTSG.
  7. Resources: MTSG GMA.
  8. Supervision: MTSG.
  9. Validation: DSV MTSG AWGF AHL.
  10. Visualization: DSV MTSG AWGF.
  11. Writing – original draft: DSV MTSG AWGF.
  12. Writing – review & editing: DSV MTSG AWGF.

References

  1. 1. Jeppson LR, Baker EW, Keifer HH. Mites Injurious to Economic Plants. University of California Press, Berkeley. 1975.
  2. 2. Welbourn WC, Ochoa R, Kane EC, Erbe EF. Morphological observations on Brevipalpus phoenicis (Acari: Tenuipalpidae) including comparisons with B. californicus and B. obovatus. Exp Appl Acarol. 2003; 30: 107–133. pmid:14756413
  3. 3. Mesa NC, Ochoa R, Welbourn WC, Evans GA, Moraes GJ. A catalog of the Tenuipalpidae Berlese (Acari: Prostigmata) of the world with a key to genera. Zootaxa 2009; 2098: 1–185.
  4. 4. Childers CC, French JV, Rodriguez JCV. Brevipalpus californicus, B. obovatus, B. phoenicis, and B. lewisi (Acari: Tenuipalpidae): a review of their biology, feeding injury and economic importance. Exp Appl Acarol. 2003; 30: 5–28. pmid:14756411
  5. 5. Bastianel M, Freitas-Astúa J, Kitajima EW, Machado MA. The citrus leprosis pathosystem. Summa Phytopathol. 2006; 32: 211–220.
  6. 6. Bastianel M, Novelli VM, Kitajima EW, Kubo KS, Bassanezi RB, Machado MA, et al. Citrus Leprosis: Centennial of an unusual mite–virus. pathosystem. Plant Dis. 2010; 94: 284–292.
  7. 7. Childers CC, Rodrigues JCV. An overview of Brevipalpus mite (Acari: Tenuipalpidae) and the plant viruses they transmit. Zoosymposia 2011; 6:180–192.
  8. 8. Chagas CM, Kitajima EW, Rodrigues VJC. Coffee ringspot virus vectored by Brevipalpus phoenicis (Acari: Tenuipalpidae) in coffee. Exp Appl Acarol. 2003; 30: 203–213. pmid:14756417
  9. 9. Kitajima EW, Rezende JAM, Rodrigues JCV, Chiavegato LG, Piza CT Jr, Morozini W. Green spot of passion fruit, a possible viral disease associated with infestation by the mite Brevipalpus phoenicis. Fitopatol Bras. 1997; 22: 555–559.
  10. 10. Kitajima EW, Rezende JAM, Rodrigues JCV. Passion fruit green spot virus vectored by Brevipalpus phoenicis (Acari: Tenuipalpidae). Exp Appl Acarol. 2003; 30: 225–231. pmid:14756419
  11. 11. Kitajima EW, Kondo H, Mackenzie A, Rezende JAM, Gioria R, Gibbs A, Tamada T. Comparative cytopathology and immunocytochemistry of Japanese, Australian and Brazilian isolates of orchid fleck virus. J Gen Plant Pathol. 2001; 67: 231–237.
  12. 12. Kitajima EW, Rodrígues JCV, Freitas-Astua J. An annotated list of ornamentals naturally found infected by Brevipalpus mite-transmitted viruses. Sci Agric. 2010; 67: 348–371.
  13. 13. Freitas-Astúa J, Moreira L, Rivera C, Rodriguez CM, Kitajima EW. First report of orchid fleck virus in Costa Rica. Plant Dis. 2002; 86: 1402.
  14. 14. Kondo H, Maeda T, Tamada T. Orchid fleck virus: Brevipalpus californicus mite transmission, biological properties and genome structure. Exp Appl Acarol. 2003; 30: 215–223. pmid:14756418
  15. 15. Rodrigues JCV, Antony LMK, Salaroli RB, Kitajima EW. Brevipalpus-associated viruses in the central Amazon Basin. Trop Plant Pathol. 2008; 33: 12–19.
  16. 16. Rodrigues JCV, Childers CC. Brevipalpus mites (Acari: Tenuipalpidae): vectors of invasive, non-systemic cytoplasmic and nuclear viruses in plants. Exp Appl Acarol. 2013; 59: 165–175. pmid:23203501
  17. 17. Beard JJ, Ochoa R, Bauchan GR, Trice MD, Redford AJ, Walters TW, et al. Flat Mites of the World Edition 2. Identification Technology Program, CPHST, PPQ, APHIS, USDA; Fort Collins, CO. 2012; [Accessed June 30, 2016] Available: http://idtools.org/id/mites/flatmites/
  18. 18. Beard JJ, Ochoa R, Braswell WE, Bauchan GR. Brevipalpus phoenicis (Geijskes) species complex (Acari: Tenuipalpidae)-a closer look. Zootaxa 2015; 3944: 1–67. pmid:25947538
  19. 19. Sánchez-Velázquez EJ, Santillán-Galicia MT, Novelli VM, Nunes MA, Mora-Aguilera G, Valdez-Carrasco JM, et al. Diversity and genetic variation among Brevipalpus populations from Brazil and Mexico. Plos One. 2015; 10: 1–16. e0133861.
  20. 20. Tsagkarakou A, Navajas M, Lagnel J, Pasteur N. Population structure in the spider mite Tetranychus urticae (Acari: Tetranychidae) from Crete based on multiple allozymes. Heredity 1997; 78: 84–92. pmid:16397641
  21. 21. Carbonelle S, Hance T, Migeon A, Baret P, Cros-Arteil S, Navajas M. Microsatellite markers reveal spatial genetic structure of Tetranychus urticae (Acari: Tetranychidae) populations along a latitudinal gradient in Europe. Exp Appl Acarol. 2007; 41: 225–241. pmid:17457678
  22. 22. Guzman-Valencia S, Santillán-Galicia MT, Guzmán-Franco AW, González-Hernández H, Carrillo-Benítez MG, Suárez-Espinoza J. Contrasting effects of geographical separation on the genetic population structure of sympatric species of mites in avocado orchards. Bull Entomol Res. 2014; 104: 610–621. pmid:24871093
  23. 23. Magalhães S, Forbes MR, Skoracka A, Osakabe M, Chevillon C, McCoy KD. Host race formation in the Acari. Exp Appl Acarol. 2007; 42: 225–238. pmid:17674128
  24. 24. Navajas M, Gutierrez J, Lagnel J, Boursot P. Mitochondrial cytochrome oxidase I in tetranychid mites: a comparison between molecular phylogeny and changes of morphological and life history traits. Bull Entomol Res. 1996; 86: 407–417.
  25. 25. Hall TA. BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acid Symp. Ser. 1999; 41: 95–98.
  26. 26. Thompson JD, Higgins DG, Gibson TJ. CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, positions-specific gap penalties and weight matrix choice. Nucleic Acids Res. 1994; 22: 4673–4680. pmid:7984417
  27. 27. Tamura K, Stecher G, Peterson D, Filipski A, Kumar S. MEGA6: Molecular Evolutionary Genetics Analysis Version 6.0. Mol Biol Evol. 2013; 30: 2725–2729. pmid:24132122
  28. 28. Felsenstein J. Confidence limits on phylogenies: an approach using the bootstrap. Evolution 1985; 39: 783–791.
  29. 29. Nei M, Gojobori T. Simple methods for estimating the numbers of synonymous and nonsynonymous nucleotide substitutions. Mol Biol Evol. 1986; 3:418–426. pmid:3444411
  30. 30. Templeton AR, Crandall KA, Sing CF. A cladistic analysis of phenotypic associations with haplotypes inferred from restriction endonuclease mapping and DNA sequence data. III. Cladogram estimation. Genetics 1992; 132: 619–633. pmid:1385266
  31. 31. Clement M, Posada D, Crandall K. TCS: a computer program to estimate gene genealogies. Mol Ecol. 2000; 9: 1657–1660. pmid:11050560
  32. 32. Excoffier L, Lischer HEL. Arlequin suite ver 3.5: A new series of programs to perform population genetics analyses under Linux and Windows. Mol Ecol Res. 2010; 10: 564–567.
  33. 33. Jensen JL, Bohonak AJ, Kelley ST. Isolation by distance, web service. BCM Genetics 2005; 6: 13.
  34. 34. Salinas-Vargas D, Santillán-Galicia MT, Valdez-Carrasco J, Mora-Aguilera G, Atanacio-Serrano Y, Romero-Pescador P. Species composition and abundance of Brevipalpus spp. on different citrus species in Mexican orchards. Neotrop Entomol. 2013; 42: 419–425. pmid:23949863
  35. 35. Mopper S, Stiling P, Landau K, Simberloff D, Van Zandt P. Spatiotemporal variation in leafminer population structure and adaptation to individual oak trees. Ecology 2000; 81: 1577–1587.
  36. 36. Cogni R, Futuyma DJ. Local adaptation in a plant herbivore interaction depends on the spatial scale. Biol J Linn Soc. 2009; 97: 494–502.
  37. 37. Sword GA, Joern A, Senior LB. Host plant-associated genetic differentiation in the snakeweed grasshopper, Hesperotettix viridis (Orthoptera: Acrididae). Mol Ecol. 2005; 14: 2197–2205. pmid:15910337
  38. 38. Groot TYM, Janssen A, Pallini A, Breeuwer JAJ. Adaptation in the asexual false spider mite Brevipalpus phoenicis: evidence for frozen niche variation. Exp Appl Acarol. 2005; 36: 165–176. pmid:16132731
  39. 39. Valade R, Kenis M, Hernandez-Lopez A, Augustin S, Mari-Mena N, Magnoux E, et al. Mitochondrial and microsatellite DNA markers reveal a Balkan origin for the highly invasive horse-chestnut leaf miner Cameraria ohridella (Lepidoptera, Gracillariidae). Mol Ecol. 2009; 18: 3458–3470. pmid:19627490
  40. 40. Pascual-Ruiz S, Gomez-Martinez MA, Ansaloni T, Segarra-Moragues JG, Sabater-Munoz B, Jacas JA, et al. Genetic structure of a phytophagous mite species affected by crop practices: the case of Tetranychus urticae in clementine mandarins. Exp Appl Acarol. 2014; 62: 477–498. pmid:24233157