Natural occurrence of entomopathogenic nematodes (Steinernema and Heterorhabditis) and nematodes in black truffle soils from Spain.

The European truffle beetle is the most important pest in black truffle () plantations. Current control methods against it are inefficient, so entomopathogenic nematodes (EPNs) could play an important role in their population regulation due to their efficacy against many soil-dwelling insect pests. A survey of EPNs and nematodes was conducted in truffle soils of Spain, considering environmental and physical-chemical soil factors. A total of 164 soil samples were collected from forests, productive plantations and null-low productive plantations, representing three distinct black truffle-growing habitat types. EPNs were isolated from seven soil samples (4.3%); four nematodes were identified as and three as Both species were sampled in three types of soil texture (loam, sandy loam or sandy clay loam), characterized by alkaline pH (7.5 to 8.5) and high organic matter (2.1-11.04%). The presence of these EPNs was influenced by habitat type and organic matter content. nematodes were isolated from truffle soil, around truffle fruit bodies and under the elytra of with being the most commonly identified species. No significant associations were found between environmental and soil factors and the occurrence of nematodes. These nematodes were found in alkaline soils (pH 7.75 to 8.7), across all seven sampled soil textures, with variable organic matter content (0.73%-5.92%). The ecological trends and the presence of may affect the occurrence of EPNs and their prospective use as biological control agents against in black truffle plantations.