Oligonychus trichardti (Acari: Tetranychidae) associated with Urochloa grasses in Kenya: an integrative taxonomic approach

Publication Type

Journal Article

Journal Name

Acarologia

Publication Date

1-1-2026

Abstract

Spider mites represent a significant constraint to improved forage grass adoption in East Africa, particularly affecting Urochloa cultivars that are crucial for addressing the region’s 40% livestock feed gap. This study employed an integrative taxonomic approach combining morphological and molecular analyses to identify a spider mite species infesting Urochloa interspecific grasses in Kenya. A colony of 80 spider mites was established from symptomatic Urochloa hybrid cv. Cayman plants collected from Mbita Point, Kenya, showing characteristic foliar chlorosis and necrotic spots. Morphological examination of 46 slide-mounted specimens using Hoyer’s medium revealed consistent morphotypical features characteristic of Oligonychus (Reckiella) trichardti Meyer, 1974. Molecular sequence data was also provided for mitochondrial cytochrome c oxidase subunit I (COI) and nuclear internal transcribed spacer 2 (ITS2) markers to supplement the morphological identification. Analysis of COI and ITS2 sequences from 10 individuals revealed identical haplotypes for both markers, reflecting the single source colony sampling and providing species level reference sequences. Maximum Likelihood analyses of COI and ITS2 datasets placed the Kenyan specimens within the subgenus Reckiella and clearly distinguished them from other sampled species. While backbone relationships among closely related taxa were moderately supported, species-level clustering was robust in both markers. This study provides the first molecular barcode identification for O. trichardti associated with Urochloa grasses in Kenya, providing essential baseline information for developing targeted integrated pest management strategies. While morphological characters allow for the clear identification of adult males, the molecular data presented here facilitate accurate species identification for immature stages and females, which otherwise lack diagnostic morphological features. This diagnostic capability is particularly significant given the taxonomic complexity within the genus Oligonychus and the agricultural importance of precise species identification for effective pest management in forage systems.

Keywords

barcoding, Brachiaria, COI, forage grasses, ITS2, red spider mite, Tetranychidae

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