Navajas, M., Gutierrez, J., Bonato, O., Bolland, H.R. and Mapangou-Divassa, S., 1994. lntraspecific diversity of the Cassava Green Mite Mononycheltus progresivus (Acari: Tetranychidae) using comparisons of mitochondrial and nuclear ribosomal DNA sequences and cross-breeding. Exp. Appl. Acarol., 18: 351-360.lntraspecific diversity in Cassava Green Mite Motwnychellus progresivus Doreste was examined using individuals collected in Benin and the Congo and in Columbia and Brazil. Comparisons were based on mitochondrial and ribosomal DNA sequences and the results of several cross-breeding experiments. Sequence variation was examined in a total of 1139 base pairs (bp) constituting the ITS2 ribosomal DNA (805 bp) and a fragment of the Cytochrome Oxidase I (COl) gene (334 bp). Sequence divergence is low, ranging from 0% to 2.1% for COI and from 0% to 0.4% for ITS2. Inter-strain comparisons have shown that the two African populations appear to be identical. They were similar to the Colombian population while the Brazilian population was clearly different. The data support the hypothesis of a single introduction olf the species in the two African populations. Crossing experinaents have shown partial hybrid sterility, suggesting a genetic incompatibility consistent with differences detected by sequence data. The results show the usefulness of molecular markers as a tool tor determining taxonomic status and dispersion paths in spider mites.

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The chromosome numbers and types of parthenogenesis have been assessed for 19 species of 6 different genera of the Tenuipalpidae. The modal number of n = 2 is found to occur in species of the genera Aegyptobia, Cenopalpus, Brevipalpus, Dolichotetranychus and Raoiella. The bisexual species examined exhibit haplo-diploidy (with n = 2 and 2n = 4) as a result of arrhenotokous parthenogenesis. Thelytokous parthenogenesis with female diploidy is found in Aegyptobia vannus (2n = 4), Aegyptobia thujae (2n = 4) and in Tenuipalpus spec. (2n = 6). Thelytoky with female haploidy exists in Brevipalpus obovatus and B. phoenicus, both with n=2.

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