Phylogenetic diversity of cassava green mite, Mononychellus progresivus from different geographical sites in east Africa

Abstract

Cassava green mite (CGM) of the Mononychellus genus is an invasive species in Africa, introduced from South America. Its phylogenetic diversity over geographical localities has never been assessed in East Africa, where mite density dynamics oscillate from few individuals to a peak of hundreds. The objective of this study was to determine CGM species comparative phylogenetic diversity from seven distinct geographical sites in East Africa. Six sites were sampled for CGM races, two samples from each country. DNA was extracted on internal transcribed spacer 2 (ITS2) and cytochrome oxidase subunit I (COI), and compared for phylogenetic variations of CGM from different locations of East African region. A comparative search from the NCBI Gene bank resulted into identical species nucleotides from Congo and Benin. Sequences from the two sites in Kenya were 99-100% similar to CGM nucleotide from the Congo-Benin accessions (X79902.1) on ITS2 gene region. On COI, a 98- 99% site sequences similarity was observed on M. progresivus accession X79901.1. A closely related divergence of specimens collected from Tanzania and Uganda was determined. Both Uganda and Tanzania had 99% match to X79901.1 on COI region. Similarly, the Uganda and Tanzania samples had 99% match to emb/X79902.1 on the 18Sr RNA region. The CGM sequence from coastal Kenya had the highest phylogenetic divergence from the Congo-Benin sequences. A small biogeographic phylogenetic divergence (0-1%) was evident from the analyses among the six collection sites. The results confirm M. progresivus identity in East Africa it also indicates intraspecies phylogenetic variations on the COI gene region of interest.