Prevalence and Population Dynamics of Phytoparasitic Nematodes Associated with Vegetable Production in Gombe State, Nigeria

Gombe is an agrarian State, with vegetables predominantly cultivated in rural communities as a major source of livelihood for the teeming farmer farmers. The activities of pests and diseases continue to devastate most vegetable fields; one such pest is plant-parasitic nematodes (PPNs), which cause significant yield loss and limit profitable production. A field study was conducted from September to October 2023 to survey PPNs associated with vegetable production in five local government areas (Akko, Balanga, Yamaltu Deba, Dukku, and Kaltungo) of Gombe State, Nigeria. The soil samples were collected via a soil auger at a depth of 0–25 cm and within 25 cm around the rhizosphere of the plants in a zig zag pattern. A total of 30 soil core samples per hectare/field from vegetable farms per LGA were randomly collected. The Whitehead and Hemming methods and identification keys were used for the soil extraction and genus identification of the PPNs, respectively. A total of 16 nematode genera ( Xiphinema, Meloidogyne, Scutellonema, Pratylenchus, Tylenchulus, Rotylenchus, Rotylenchulus, Helicotylenchus, Paratylenchus, Trichodorus, Tylenchus, Longidorus, Heterodera, Aphelenchus, Hoplolaimus , and Aphelenchoides ) belonging to distinct families were found to be associated with some cultivated vegetables from the five LGAs surveyed. The greatest number (15) of PPN genera was recovered from Akko, followed by Kaltungo and Yamaltu Deba (14) and Balanga (13), whereas Dukku recorded the lowest number (10). Meloidogyne presented the highest mean relative abundance (20%) and population density (464) in all surveyed LGAs of the state. This was followed by Scutellonema (10%, 231) and Xiphinema (9%, 219), whereas Rotylenchulus (4%, 109) and Aphelenchus (4%, 100) presented the lowest percentages. In terms of frequency of occurrence, Meloidogyne had the highest frequency of occurrence (100%) irrespective of the LGA surveyed, and Tylenchus had the lowest frequency of occurrence (30, 20, and 15%) in Balanga, Kaltungo, and Y/Deba LGAs, respectively, whereas Hoplolaimus and Paratylenchus were the least common genera (45%) in Akko and Dukku. Compared with the other LGAs, Akko presented the highest Shannon diversity index (2.62) and evenness (0.92), indicating greater diversity and a more balanced distribution of PPNs among species. Kaltungo and Yamaltu Deba presented the maximum similarity (100%) in terms of PPN genera. These findings highlight the widespread distribution of important yield-limiting PPNs and the dominance of root-knot nematodes on vegetable farms in Gombe State, revealing the need for management strategies and further research on nematode–host dynamics to safeguard vegetable production and improve farmer livelihoods.