Molecular approach to confirm traditional identification of Radopholus similis sampled in Tanzania

Banana (Musa spp. L.) is an important staple food and cash crop for about 30% of the population in Tanzania; however, the burrowing plant-parasitic nematode Radopholus similis causes black head disease and toppling in banana plants, which results in yield losses. We collected and identified 80 specimens of R. similis from four agro-ecological zones in Tanzania using morphological characters. We then used universal and specific R. similis primers to amplify the small subunit, internal transcribed spacer and large subunit of ribosomal DNA regions of these specimens. The amplicons were subsequently sequenced and analyzed using Bayesian inference. We identified two major clades, one that comprised all R. similis sequences derived from this study and another that included R. similis and Radopholus spp. sequences obtained from GenBank, indicating the separation of this species from congeneric sequences. Our findings provide a useful, simple and rapid method for identifying burrowing nematodes. This outcome could contribute to the development of permanent, integrated pest management strategies for the control of R. similis in banana and other crops in order to reduce associated yield losses in Tanzania. To our knowledge, this is the first study of nematodes to use combined morphological and molecular methods for the identification of R. similis in Tanzania.