Incidence and Characterization of Rice Root Nematodes, Hirschmanniella mucronata, from Rice Fields in Pathum Thani Province, Thailand

The rice root nematodes, Hirschmanniella oryzae and H. mucronata, are serious and widespread threats to global rice production, especially in tropical and subtropical zones. Reliable and efficient identification of these nematodes is vital to nematode control and management. In this current study, 36 soil or rice root samples were collected from rice fields located in Pathum Thani province and used for nematode extraction. The results demonstrated that Hirschmanniella sp. was found in all paddy fields, especially in Muang District, where RD47 rice cultivars were grown at soil pH of 5.9. Molecular identification based on the analysis of 28S rRNA and 18S-ITS1-1.58S genes revealed 98 – 99 % similarity to H. mucronata, and its phylogenetic trees were grouped with H. mucronata from Cambodia and Philippines. Likewise, the morphometric characterization revealed remarkable features of H. mucronata with long body (1,639 - 2,329 µm), long stylet (24 - 27 µm) and an obvious mucron at the end of terminus. Therefore, the main rice root nematode species found in Pathum Thani’s rice fields were H. mucronata. HIGHLIGHTS The rice root nematodes, Hirschmanniella, are presented the predominant plant-parasitic nematodes in rice cultivated areas of Pathum Thani province, Thailand Population densities of Hirschmanniella are encountered in rice roots than in soil, especially in RD47 rice cultivars grown in Muang District Both of morphological and molecular characterization illustrating the species of rice root nematodes were mucronate This is a first description on the molecular characterization of mucronata from rice fields in Thailand GRAPHICAL ABSTRACT