HOST FINDING BEHAVIOR AS A PREDICTOR OF FORAGING STRATEGY IN ENTOMOPATHOGENIC NEMATODES

Foraging strategies of eight species of entomopathogenic nematodes wer e predicted from their response to host volatile cues and dispersal be haviour on 2-dimensional substrates. Positive directional response to chemical cues and similar distances travelled on smooth (agar) or nict ation substrates (agar overlaid with sand grains) by Heterorhabditis b acteriophora, Heterorhabditis megidis, Steinernema anomali, and Steine rnema glaseri suggest their cruising approach to finding hosts. The ab sence of directional response and less distance travelled on nictation substrate, than on smooth agar by Steinernema carpocapsae and Steiner nema scapterisci suggest their ambushing mode of foraging. Steinernema feltiae and Steinernema sp. responded directionally to host volatiles , but travelled less distance on the nictation substrate than on smoot h agar; the two species also did not nictate. The cruiser species loca ted hosts more effectively in the sand columns, whereas the ambushers were more effective at finding hosts on filter paper. Steinernema felt iae and Steinernema sp. performed equally on filter paper and in the s and column. We conclude that H. bacteriophora, H. megidis, S. anomali and S. glaseri cruise to find hosts, whereas S. carpocapsae and S. sca pterisci ambush hosts. Steinernema feltiae and Steinernema sp, are int ermediary in the search continuum sharing some characteristics of both ambush and cruise foragers.