Spatial distribution and community analysis of plant-parasitic nematodes associated with rice (Oryza sativa L.) in Benue State, Nigeria

Abstract

Plant-parasitic nematodes (PPNs), also known as phyto-parasitic or plant-destructive nematodes are microscopic, translucent, bilaterally symmetrical, pseudocoelomic, multicellular worm-like organisms which feed on plant root mostly, and seldom on other vegetative parts. Although these PPNs have been reported to constitute threat to rice production, documentation of their spatial distribution and densities in major rice-producing areas of Benue state, Nigeria is absent. Using multi-stage sampling procedure, surveillance for PPNs, their densities and community analyses were conducted in six major rice-producing local government areas (LGAs) of Benue. The LGAs included Agatu, Apa, Gwer West, Guma, Kwande and Makurdi LGAs and a total of 108 samples were collected comprising 54 soil and 54 root samples. Nine plant-parasitic nematode genera which included Criconemoides, Tylenchorhynchus, Trichodorus, Hirschmanniella, Xiphinema, Helicotylenchus, Scutellonema, Pratylenchus and Meloidogyne were recovered. In order of ranking, Meloidogyne sp., P. zeae and H. oryzeae had the highest population densities across all LGAs included in the study. The highest density of PPN was recorded in Kwande (ca. 133 PPNs/10mL of nematode suspension) while lowest population density was recorded in Makurdi (ca. 77 PPNs/10mL of suspension). Although Meloidogyne sp. recorded the highest average population density in all LGA except in Gwer West LGA where H. oryzae recorded the highest average population density of approximately 13 PPNs/10mL of suspension. Community analysis also revealed that Meloidogyne sp. was the most spatially distributed PPN closely followed by P. zeae and H. oryzae with prominence values of 37.78, 21.84 and 20.91, respectively. However, in the soil, the highest prominence value was recorded in H. oryzae making it the most spatially distributed PPN in the soil.