INTEGRATING CASSAVA VARIETIES AND Typhlodramulus aripo TO SUSTAIN BIOLOGICAL CONTROL OF CASSAVA GREEN MITE

The cassava green mite (CGM), Mononychellus tanajoa , is a pest that reduces root yield of cassava ( Manihot esculenta Crantz) by 30-80% in the cassava belts of Africa. The objective of this study was to identify cassava varieties that enhance abundance and persistence of Typhlodramulus aripo on cassava and increase its efficiency in controlling CGM. Nine cassava (Manihot esculenta Crantz) varieties were evaluated in Kenya based on CGM abundance and HCN of leaves for their ability to sustain low CGM populations to enhance biocontrol of T. aripo. Cassava fields were surveyed in five agro-ecological zones in Uganda and samples of cassava apices were analysed for cassava varieties to sustain high population of T. aripo. In the screening study of CGM abundance and HCN content of leaves and the lowest cumulative CGM population densities (<1200 mites/leaf) were recorded on MM97/3567, Tajirika and MM96/9308, with the lowest cyanide content of leaves, 8.5 \ub1 4.9, 12.5 \ub1 3.2 and 12.3 \ub1 2.5 mg kg-1, respectively. Cassava varieties with hairy and non-hairy tips sustained T. aripo with highest densities (0.96 actives per tip) on hairy TME14. High T. aripo population densities corresponded to high densities of hairs on cassava tips. There were significant inverse linear relationships between CGM densities and T. aripo on TME14 at moderate CGM population densities (CGM damage level 2).Le tantinet vert de la cassave (CGM), Mononychellus tanajoa , est un insecte nuisible qui r\ue9duit la production de racine de cassave ( Manihot esculenta Crantz) de 30-80 % dans les ceintures de cassave de l\u2019Afrique. L\u2019objectif de cette \ue9tude \ue9tait d\u2019identifier des vari\ue9t\ue9s de cassave qui am\ue9liorent l\u2019abondance et la persistance de Typhlodramulus aripo sur la cassave et augmentent son efficacit\ue9 dans le contr\uf4le de CGM. Neuf cassave (Manihot esculenta Crantz) les vari\ue9t\ue9s ont \ue9t\ue9 \ue9valu\ue9es au Kenya bas\ue9 sur l\u2019abondance CGM et HCN de part pour leur capacit\ue9 de soutenir bas des populations de CGM pour am\ue9liorer biocontrol de T. aripo. Les champs de cassave ont \ue9t\ue9 \ue9tudi\ue9s dans cinq zones agro-\ue9cologiques en Ouganda et les \ue9chantillons de sommets de cassave ont \ue9t\ue9 analys\ue9s pour les vari\ue9t\ue9s de cassave pour soutenir la haute population de T. aripo. Dans l\u2019\ue9tude de projection d\u2019abondance CGM et de contenu de HCN de cong\ue9s et des densit\ue9s d\ue9mographiques CGM cumulatives les plus basses (<1200 tantinets/feuille) ont \ue9t\ue9 enregistr\ue9s sur MM97/3567, Tajirika et MM96/9308, avec le contenu de cyanure le plus bas de cong\ue9s, 8.5 \ub1 4.9, 12.5 \ub1 3.2 et 12.3 kg de 2.5 mgs \ub1 1, respectivement. Les vari\ue9t\ue9s de cassave avec les bouts poilus et non-poilus ont soutenu T. aripo avec les plus hautes densit\ue9s (0.96 actives par bout) sur TME14 poilu. Haut T. aripo les densit\ue9s d\ue9mographiques a correspondu \ue0 de hautes densit\ue9s de hairs sur les bouts de cassave. Il y avait des rapports lin\ue9aires inverses significatifs entre les densit\ue9s CGM et T. aripo sur TME14 aux densit\ue9s d\ue9mographiques CGM mod\ue9r\ue9es (le niveau de dommage de CGM 2)

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

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 intra-species phylogenetic variations on the COI gene region of interest.L\u2019acarien vert du manioc (CGM) du genre Mononychellus est espece invasive Introduite de l\u2019Amerique du Sud en Afrique. Sa diversite phyllogenetique au sein et entre les localites n\u2019a jamais ete evaluee en Afrique de l\u2019Est, ou la densite d\u2019acarien varie de quelques individus a plusieurs centaines. L\u2019objectif de cette etude etait de determiner la diversite phyllogenetiques des especes CGM et de comparer sept sites geographiquement differents en Afrique de l\u2019Est. six sites ont ete echantillonnes pour des races de CGM, a raison de deux echantillons par pays. De l\u2019AND a ete extrait sur l\u2019espaceur interne transcrit 2 (ITS2) et sous-unite I de cytochrome oxidase (COI), ces echantillons ont ete compares pour les variations phyllogenetiques de CGM provenant de localites differentes de la region Est Africaine. Une etude comparee a la banque de gene de NCBI a revele des especes identiques en provenance de Congo et du Benin, de point de vue de leur nucleotides. Des sequences provenant des deux sites au Kenya ont exhibe 99-100% de similarite avec les nucleotides de CGM provenant des accessions Congo-Benin (X79902.1) sur la region genetique ITS2. Sur COI, une similarite de 98-99% a ete observee sur l\u2019accession M. progresivus X79901.1. Une divergence de sujets genetiquement proches a ete observe chez des specimens collectes en Tanzannie et en Ouganda. Ouganda et Tanzanie ont exhibe 99% de similitude a X79901.1 sur la region COI. De meme, les echantillons provenant de Ouganda et de Tanzannie presentaient 99% de similitude avec emb/X79902.1 sur la region 18Sr RNA. La sequence de CGM provenant de cote kenyane avait la divergence phyllogenique la plus elevee d\u2019avec les sequences Congo-Benin. Une legere divergence phyllogenetique geographiaque (0-1%) a ete note des analyses dans les sites de collection. Les resultats conferment l\u2019identite de M. progresivus identity en Afrique de l\u2019Est. l\u2019etude a aussi revele des variations phyllogenetiques sur la region de gene d\u2019interet COI

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