Genetic analysis of the tomato russet mite provides evidence of oligophagy and a widespread pestiferous haplotype.

Worldwide, the tomato russet mite (TRM), Aculops lycopersici (Eriophyidae), is a key pest on cultivated tomato in addition to infesting other cultivated and wild Solanaceae; however, basic information on TRM supporting effective control strategies is still lacking, mainly regarding its taxonomic status and genetic diversity and structure. As A. lycopersici is reported on different species and genera of host plants, populations associated with different host plants may constitute specialized cryptic species, as shown for other eriophyids previously considered generalists. The main aims of this study were to (i) confirm the TRM taxonomic unity of populations from different host plants and localities as well as the species' oligophagy, and (ii) to advance the understanding of TRM host relationship and invasion history. For this purpose, we evaluated the genetic variability and structure of populations from different host plants along crucial areas of occurrence, including the area of potential origin, based on DNA sequences of mitochondrial (cytochrome c oxidase subunit I) and nuclear (internal transcribed spacer, D2 28S) genomic regions. Specimens from South America (Brazil) and Europe (France, Italy, Poland, The Netherlands) were collected from tomato and other solanaceous species from the genera Solanum and Physalis. Final TRM datasets were composed of 101, 82 and 50 sequences from the COI (672 bp), ITS (553 bp) and D2 (605 bp) regions, respectively. Distributions and frequencies of haplotypes (COI) and genotypes (D2 and ITS1) were inferred; pairwise genetic distance comparisons, and phylogenetic analysis were performed, including Bayesian Inference (BI) combined analysis. Our results showed that genetic divergences for mitochondrial and nuclear genomic regions from TRM associated with different host plants were lower than those observed in other eriophyid taxa, confirming conspecificity of TRM populations and oligophagy of this eriophyid mite. Four haplotypes (cH) were identified from the COI sequences with cH1 being the most frequent, representing 90% of all sequences occurring in all host plants studied (Brazil, France, The Netherlands); the other haplotypes were present exclusively in Brazilian populations. Six variants (I) were identified from the ITS sequences: I-1 was the most frequent (76.5% of all sequences), spread in all countries and associated with all host plants, except S. nigrum. Just one D2 sequence variant was found in all studied countries. The genetic homogeneity among populations highlights the occurrence of a highly invasive and oligophagous haplotype. These results failed to corroborate the hypothesis that differential symptomatology or damage intensity among tomato varieties and solanaceous host plants could be due to the genetic diversity of the associated mite populations. The genetic evidence, along with the history of spread of cultivated tomato, corroborates the hypothesis of a South American origin of TRM.

Integrative taxonomy of Abacarus mites (Eriophyidae) associated with hybrid sugarcane plants, including description of a new species.

Phytophagous mites belonging to the Eriophyoidea are extremely diverse and highly host-specific. Their accurate morphological identification is hampered by their reduced size and simplified bodies and by the existence of cryptic species complexes. Previous studies have demonstrated the urgency of applying multisource methods to accurate taxonomic identification of eriophyoid mites, especially species belonging to the genus Abacarus. This genus comprises 65 species, of which 37 are associated with grasses and four with sugarcane Saccharum (Poaceae). Recently, Abacarus specimens very similar to Abacarus sacchari were collected from the sugarcane crop in Brazil; however, their taxonomic placement was uncertain. In this study, we used an integrative approach to determine whether A. aff. sacchari specimens belong to A. sacchari or constitute a cryptic species. Morphological data were combined with molecular phylogeny based on the nucleotide sequences of three markers, one mitochondrial (COI) and two nuclear (D2 region of 28S and ITS). Morphological differences were observed between A. aff. sacchari, A. sacchari and A. doctus. The phylogenetic relationships among these three taxa and the genetic distances separating them revealed an interspecific divergence. The results of the morphological and molecular methods were congruent and supported the existence of a new species: Abacarus neosacchari n. sp. Duarte and Navia, herein described. This species belongs to the Abacarus cryptic species complex associated with sugarcane in the Americas. The results of this study, presenting the occurrence of multiple Abacarus species associated with sugarcane, contribute to the knowledge on plants and mites diversity by adding up one more clue highlighting that plant hybridization can be an important mechanism contributing to the speciation of plant-feeding arthropods.

Eriophyoid mites (Acari: Prostigmata) from Brazil: an annotated checklist.

The superfamily Eriophyoidea constitute a group of phytophagous mites of particular economic and evolutionary interest due to their intimate association with host plants and their agricultural importance as harmful or beneficial organisms. Studies on the Eriophyoidea fauna in Brazil started in the early 1900s with botanical works on cecidias and were continued with researchers looking for and reporting on eriophyid mites causing damage to agricultural crops. Therefore, in this annotated checklist, we compile information from just over a century on eriophyid mites reported or described from Brazil. Its purpose is to facilitate plant protection strategies and guide future work on this important group of phytophagous mites. In addition to taxonomy, we present information on host plants and general aspects of cecidia attributed to eriophyoid mites but without genus/species identification. Compilation was based on: i) literature, including papers, books, theses and congress/symposium publications; ii) specimens deposited in mite collections in Brazil. On each species we present: i) suprageneric/generic classification, synonyms and previous genus/era assignments, including references on original and/or additional descriptions; ii) type host plant and other host(s) plant(s) found in the country; iii) host relationships and remarks on symptoms; iv) localities of occurrences at States/Federal District and municipal levels; and v) host plant status in Brazil as well as biomes where they occur or are cultivated. A total of 234 valid eriophyoid mite species are recorded: 196 Eriophyidae, 20 Diptilomiopidae and 18 Phytoptidae, distributed in 92 genera. Host plants comprised 233 species, belonging to 141 genera and 56 plant families. Four new reports of eriophyoid mites in Brazil are presented based on specimens deposited in reference collections. A new combination is presented for Propeaciota secundum (Flechtmann, Amrine Stasny) in the genus Khanthongella. In addition, data on observations and descriptions of 67 cecidias attributed to eriophyoid mites in five states and on 21 plant families are presented. Geographically, the distribution of species reports of eriophyoids around Brazil is highly uneven, with more than 64% of species (151 spp.) in the Southeast region, which surely reflects a lack of research elsewhere. Regarding host plant specificity, 77.7% are reported on only one host species, 88.9% on one host genus and 98.3% on one host family. Regarding host status 64.1% of species are exclusively associated with native host plants, 27% with naturalized or exotic cultivated host plants, and 6.4% from both native and naturalized or exotic host plants.