Abundance and identity of red spider mite species on Brachiaria grass in Kenya and its worldwide comparative phylogeny

Brachiaria grass in Kenya offers a vigorous and nutrient rich-forage option. Invasion of introduced Brachiaria grass in Kenya by red spider mite (RSM) indicates considerable damage during the dry season. A survey on the level of mite infestation and identification on various Brachiaria grass cultivars was carried out in August and October in 2016 in coastal lowlands, eastern, central, and western regions of Kenya. DNA-based identification was carried out using universal primers of internal transcribed spacer (ITS2) and cytochrome oxidase I (COI) gene regions. The abundance and damage by RSM were severe in eastern and western areas of the country with cvs. Marandu and Mulato II showing the highest level of infestation. BLAST results from the NCBI database revealed the red spider mite species damaging Brachiaria grass to be Tetranychus urticae (Koch.). The countrywide sequence samples did not show a much intraspecific genetic difference on COI region from the local populations but a marked wide phylogeny difference from the similar ITS2 region. The large divergence difference (> 0.10) calls for a repeat of the work in future to ascertain species delineation