Effects of the invasive tomato red spider mite (Acari: Tetranychidae) on growth and leaf yield of African nightshades

• Published in: Crop protection 2014-05, Vol.59, p.57-62
• Main Authors: Murungi, Lucy K., Salifu, Daisy, Masinde, Peter, Wesonga, John, Nyende, Aggrey, Knapp, Markus
• Format: Article
• Language: English
• Subjects: Acari; Araneae; Growth parameters; Lycopersicon esculentum; Productivity; Solanum; Solanum americanum; Solanum sp; Tetranychidae; Tetranychus; Tetranychus evansi; Tolerance
• ISSN: 0261-2194; 1873-6904
• DOI: 10.1016/j.cropro.2014.02.001

The tomato red spider mite, Tetranychus evansi Baker and Pritchard, is one of the most serious pests of solanaceous crops in Africa. Field experiments were conducted to investigate its effects on the growth and leaf yield of five African nightshade species viz. Solanum americanum, S. sarrachoides, S. scabrum, S. tarderemotum and S. villosum during the 2008 and 2009 growing seasons. Plants were infested with 2–4 day-old female spider mites which were allowed to multiply. The number of mite motiles increased throughout the growing season in unsprayed plots and this number varied significantly between the African nightshade species. Except for S. sarrachoides, leaf damage was high on the other four Solanum species irrespective of the spraying regime during both seasons. However, S. scabrum had a significantly greater leaf area ratio (ratio of leaf area to total plant weight) and specific leaf area (ratio of leaf area to total leaf dry weight) during both seasons. Overall yields were 1.5 times more in S. scabrum and S. sarrachoides compared to S. americanum, S. tarderemotum and S. villosum. Our results show that T. evansi infestation affects the leaf area ratio and specific leaf area of African nightshade species differentially which eventually determines the plant's overall leaf yield. These findings present an opportunity for evaluation and selection of African nightshade species that can withstand spider mite infestation in small holder farms for increased vegetable production in Africa. •Tetranychus evansi is an invasive pest of solanaceous crops including African nightshades.•Effects of T. evansi on growth and leaf yield of five Solanum species was studied.•T. evansi did not cause any leaf damage on one of the species, Solanum sarrachoides.•Solanum scabrum produced high yields despite being infested by high mite populations.•T. evansi differentially affected growth and leaf yield of Solanum species.