Occurrence of root-knot nematodes (Meloidogyne spp.) in vegetable crops in the eastern Amazon

Abstract

Root-knot nematodes (Meloidogyne spp.) are major phytoparasites affecting vegetable crops in tropical agroecosystems, largely due to their wide host range. This study aimed to investigate the occurrence of Meloidogyne species populations in vegetable-producing areas of the eastern Amazon. Nematological surveys were conducted on 27 agricultural properties across 10 municipalities in northeastern Pará state, Brazil. Soil and root samples were collected, processed, and analyzed to identify nematode species using morphological and biochemical characterizations. Meloidogyne spp. were found in all surveyed municipalities, identifying M. incognita, M. javanica, and M. enterolobii, with M. incognita predominating in both egg and juvenile stages. Among the crops assessed, Amazonian chicory exhibited considerable host potential, as indicated by galls indices ranging from high to extremely high. Elevated population densities of M. enterolobii were found in soil and root samples from the municipality of Capanema (39,990 eggs and Js in 100 cm3 of soil and 1998 eggs and Js in 10 g of roots), suggesting that this area may serve as an important multiplication zone. Some agricultural practices can influence this nematode population growth, especially in municipalities characterized by successive host cropping, irrigation, chemical fertilization, and inadequate weed management. Thus, identifying species, infestation levels, and hosts is essential to support integrated nematode management and develop effective strategies suited to the soil and climate conditions of the Amazon region.