Influence of insect associated cues on the jumping behavior of entomopathogenic nematodes (Steinernema spp.)

The infective stage juveniles of insect parasitic nematodes in the family Steinernema search for hosts using strategies ranging from ambush to cruise foraging. Infective juveniles attach to passing insects by standing on their tails and contacting an insect directly when standing or by jumping. We determined how species with differing degrees of ambush foraging specialization differ in their behavioral responses to different sources of information. Mechanical contact, air movement, and host associated volatile cues were important triggers of jumping behavior for some species of Steinernema. Three species that are ambush foragers (S. carpocapsae, S. scapterisci, and S. siamkayai) responded to small air movements by increased waving and jumping behavior, and jumps were directionally biased towards the source of the movement. For S. carpocapsae and S. scapterisci, host-associated volatile cues were strong triggers to jump, but host cues did not increase the proportion of S. siamkayai jumping. In contrast, two intermediate foraging species, S. ceratophorum and S. monticolum, did not demonstrate a detectable response to either the air movement or the host cues.