Entomopathogenic nematodes: host-finding ability in the presence of plant roots

The host-finding ability of Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann) and Steinernema feltiae Filipjev in the presence of plant roots in sandy soil was investigated. During a 7-d period, host-finding ability of H. heliothidis was not impaired when the dried root weights of corn, tomato, or marigold plants were 1.5 g. Thus, treatments with root weights> 1.5 g had significantly lower host mortalities (range, 27–50%) compared with control treatments (range, 73–96%); treatments with root weights 1.5 g were observed for H. heliothidis , this nematode species showed greater motility, hence greater host-finding ability, than S. feltiae in the presence of roots because host mortality occurred over a shorter period of time with higher mortality rates and with fewer nematodes.