Evaluation of the morphological and genetic diversity of different species of Brevipalpus species (Acari: Tenuipalpidae) and their competence as virus vectors

Author(s)

Aline Daniele Tassi

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2018-03-06

Examining board members

Elliot Watanabe Kitajima; Juliana de Freitas Astúa; Denise Návia Magalhães Ferreira; Gilberto José de Moraes; Valdenice Moreira Novelli

• Advisor: Elliot Watanabe Kitajima

Abstract

Brevipalpus (Acari: Prostigmata: Tenuipalpidae) are commonly found in tropical and subtropical regions. The genus includes more than 280 species, with some economically relevant for causing damage to various crops, as pests and also by transmitting plant viruses, being B. californicus Banks, B. obovatus Donnadieu and B.phoenicis (Geijskes) recognized as vectors. However B. phoencis underwinet a recent review, recognizing a species complex, thus missing the reference of which species are involved in virus transmission. Among the Brevipalpus transmitted virus (BTVs) are citrus leprosis (citrus leprosis virus C. CiLV-C), which is considered the main viral disease in the citrus industry. In the state of São Paulo, Brazil, the world largest producer of sweet orange juice, about $ 80 million/year are spent with acaricides for control the mite vector. This work had the objective pf contributing th the systematics of the group and identify the species involved with VTBs. Knowing the vectors in one of the first stages for studies of epidemiology and management of these viruses. The specific objectives were: perform a survey of Brevipalpus mites infesting different plants, mainly plant with VTBs reported; the morphological study of the species collected during this study and those deposited in the reference collection at the Museum of Zoology of the Escola Superior de Agricultura Luiz de Queiroz (MZLQ) using the newly introduced morphological criteria to identify the species of Brevipalpus that are present in Brazil; carry out BTV transmission tests and evaluating the species present in symptomatic plants that act as vectors; evaluate different molecular markers and DNA extraction protocols for Brevipalpus to generate information on diversity of mites associated with plants with BTV; and an integrative taxonomic approach, comparing morphological and molecular data for the species studied. More than 15000 mites collected from 23 countries and 75 botanical families were analyzed by light and scanning microscopy. At least 37 species and/or morphospecies. Microplates and spermathecae vesicles were evaluated and considered a fundamental characteristic in the distinction of some species of the genus. The ultrastructure of the microplates was basically similar in all the studied cases, and that they are not composed of waxy material, rather by a complex of microtubule-like structure. B. yothersi Baker was the main mite associated with commercial orange orchards with presence of CiLV-C, found during this survey. Ligustrum leprosis virus (LigLV) has been observed to be transmitted by B. papayensis Baker and B. yothersi; clerodendrum chlorotic spot virus (ClCSV) by B. yothersi; citrus leprosis virus N (CiLV-N) by B. phoenicis; and citrus chlorotic spot virus (CiCSV) by a possible new species of Brevipalpus (in this work Brevipalpus sp. nova 3). In the molecular markers assays, five DNA extraction protocols were tested, one of them permitted to extract DNA from a single mite for studies with markers and detection of viral RNA concomitantly. Of the four new primers designed, two have potential for phylogenetic studies. Sequences of 166 specimens were obtained for at least one marker. Phylogenetic analysis from two fragments of mitochondrial DNA COI region and nuclear region (ITS2 and 28S) demonstrated congruence in the separation of the species studied by morphological and molecular criteria confirming the presence of new species or morphospecies in the genus described in this work. (AU)