Sistemática morfológica e molecular de ácaros fitófagos do gênero Brevipalpus Donnadieu de importância econômica e quarentária para o Brasil / Morphological and molecular systematics of phytophagous mites of brevipalpus donnadieu genus of economic and quarantine importance to Brazil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Brevipalpus Donnadieu is the most importante genus in the Tenuipalpidae family. This genus presents about 300 species distributed around the world. Brevipalpus mites present agricultural importance because they are pests of several crops and especially due to their role as vectors of serious plant viroses. In Brazil, the main Brevipalpus species are B. phoenicis (Geijskes), B. obovatus Donnadieu and B. californicus (Banks). Brevipalpus chilensis Baker is of quarantine expression to Brazil and presents a high risk of introduction into the country through the movement of plant material. Brevipalpus species are morphologically very close which has caused some misidentification. This difficulty in identifying Brevipalpus species has caused problems to the Brazilian exportations and to the interception of quarantine species in the entry points in Brazil. The main goal of this work was to give support to a fast and accurate identification of Brevipalpus species and contribute to the systematic of the group. Three chapters are presented and their specific objectives were: 1) contribute to the knowledge on the host range and distribution of Brevipalpus mites in Brazil through collections as well as data compilation; 2) describe B. chilensis phenotypic variability among populations of different hosts and localities in Chile, using morphometric multivariate analysis and investigate whether or not the observed variation is associated with the host or geographic origin; 3) contribute to the knowledge on the molecular systematic of Brevipalpus and evaluate the potential of the mitochondrial DNA Cytochrome Oxidase subunit I (CO-I) to define speciesspecific primers to the identification of Brevipalpus. Brevipalpus mites were found in 70 host plants, and four species were identified from the sampled plants: B. californicus, B. cassia, B. obovatus and B. phoenicis. Five new hosts are reported to B. phoenicis, two to B. californicus, one to B. cassia and one to B. obovatus. Up to now, in Brazil Brevipalpus mites present about 250 hosts distributed in 133 localities. Results of morphometric analysis indicate that B. chilensis presents intrainterpopulational morphometric variability. It was not possible to detect the presence xii of isolated clusters among the studied populations, which could justify distintion of subspecific categories. Data analysis showed that the morphometric variation in B. chilensis is related to the host plants, and not to their geographic origin. The morphometric characterization of B. chilensis revealed the potential of characters, previously not explored, as useful to the distinction between the quarantine mite B. chilensis and B. obovatus. In the molecular systematic studies, a CO-I fragment of 430pb was amplified and sequenced. A total of 49 Brevipalpus samples were obtained. In the analysis there were included 41 Brevipalpus sequences retrieved from the GeneBank. Two main clades were observed - 1) B. phoenicis; 2) B. chilensis and B. aff. chilensis, B. obovatus, B. californicus, B. aff. phoenicis. Results support the present taxonomy of B. obovatus and B. chilensis as distinct taxa as well as the hypothesis of a species complex within B. phoenicis phenotypes. CO-I polymorphism among the studied Brevipalpus species seems to perform poorly in defining species-specific primers and other genomic regions should be explored for diagnostics. CO-I region is phylogenetically informative. Future perspectives to follow studies on morphological and molecular systematic on Brevipalpus are addressed.

ASSUNTO(S)

américa do sul defesa fitossanitária false spider mites ciencias agrarias marcador molecular taxonomia south america ácaros fitófagos phytophagous mites ácaros planos plant protection taxonomy molecular marker

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