The aim of this study was to evaluate the resistance of cassava genotypes to Mononychellus tanajoa (Bondar) and population dynamics of this mite in the Roraima Savannah. To assess non-preference of feeding and oviposition by M. tanajoa were used thirty cassava genotypes from the active germplasm collection of Centro de Ciências Agrárias da Universidade Federal de Roraima - CCA/UFRR. Also held the counting of the number of trichomes on 4 mm² of each leaflet from the third fully expanded leaf from apex to base, to get the average density of trichomes per plant. These data were correlated with the number of mites and eggs per cm² using the Pearson correlation coefficient, performed by the statistical program BioEstat version 5.0. The population dynamics of M. tanajoa was monthly evaluated, from January to December 2015. For counting the number of eggs and mites it was used the third and fourth fully developed leafs, from plants of Aciolina cultivar. The cultivars Amazonas, Recife, Pão and Cigana- Preta can be classified as less preferred for oviposition by M. tanajoa, and the cultivars Cigana-preta, Recife and Pão are also less preferred for feeding by that mite. Among the clones from Aciolina cultivar, the clone AC100 can be classified as less preferred for oviposition and feeding by M. tanajoa. For the clones from Gabriela cultivar, the clones G92 and G83 can be classified as less preferred for oviposition and feeding by M. tanajoa. The average density of trichomes interfered negatively in the population of M. tanajoa. Climatic factors affected the population dynamics of M. tanajoa on Aciolina cultivar, cultivated in Roraima savannah.
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