Natural occurrence of entomopathogenic nematodes (Rhabditida : Steinernema, Heterorhabditis) in the Azores

A soil survey for entomopathogenic nematodes was conducted throughout the n ine islands of the Azorean archipelago. Forty-six out of 1,180 samples (3.9 %) were positive, with Heterorhabditis spp. isolated from 30 sites on six i slands and Steinernema spp. isolated from 16 sites on three islands. Sao Mi guel and Terceira Islands were positive for both genera, and Pico Island wa s positive only for Steinernema. Entomopathogenic nematodes were found from sea level up to 750 m. Seventy percent of the samples positive for Heteroh abditis were collected below 150 m, whereas 62.5% of the samples positive f or Steinernema were collected above 300 m. Heterorhabditis was not isolated above 450 m. Steinernema was collected mostly in loamy-sand and sandy-loam soils with a pH below 6, whereas Heterorhabditis was mostly collected in s andy and loamy-sand soils with pH higher than 6. Steinernema and Heterorhab ditis were found in cropland, orchards, and pastures, while Heterorhabditis was found also in woodland and native vegetation.