Plant-parasitic nematodes associated with rice fields in Venezuela

摘要

A nematological survey of rice (Oriza sativa L.) and weeds commonly growing in rice fields was conducted in Guarico, Cojedes and Portuguesa states. Nine species of plant-parasitic nematodes were found associated with rice fields and weeds. They were: Helicotylenchus concavus, H. pseudorobustus, Hirschmanniella oryzae, H. spinicaudata, H. caudacrena, Meloidogyne salasi, Mesocriconema onoense, Pratylenchus zeae and Tylenchorhynchus annulatus. The most important and frequently detected species were Hirschmanniella spp., M. salasi and T annulatus. Meloidogyne salasi is recorded for the first time in Venezuela, and H. concavus and H. pseudorobustus are recorded for the first time on rice in Venezuela. Root lesions and galls were commonly observed on rice roots infected with P. zeae and Hirshmanniella spp. and M. salasi, respectively. In the roots of several weed species, such as Oryza sativa (black rice), Echinochloa colonum, E. polystachya, Cyperus sp., Luziola subintegrata and Ischaemum rugosum, all developmental stages of Hirschmanniella spp. were found, while females and egg masses of M. salasi were only detected on black rice and Cyperus sp. Tylenchorhynchus annulatus was detected in the rhizosphere of all weed species, whereas Helicotylenchus spp. and M. onoense were encountered mainly in the rhizosphere of Poaceae.