Entomopathogenic nematode host finding: response to host contact cues by cruise and ambush foragers

Abstract

SUMMARYSearch behaviour of two entomopathogenic nematode species with different foraging strategies was compared by measuring parameters of unrewarded search after contact with host cues. Steinernema glaseri cruises in search of hosts. Steinernema carpocapsae ambushes hosts. Nematodes should respond to contact with relevant host cues by shifting their search from ranging to localized after contact with them. We predicted that cruising foragers rely on chemical cues more heavily than ambushers. These species were also tested for host affinities. Nematodes were tracked by image analysis after exposure to faeces, cuticle or food of either Popillia japonica or Spodoptera exiqua. Steinernema glaseri responded to selected host cues by shifting from ranging to localized search, characterized by decreased locomotory rate, distance travelled, search area and the proportion of the test period spent moving. Steinernema carpocapsae did not respond to host cues. Steinernema glaseri responds to selected chemical host cues for host location, whereas S. carpocapsae does not.

Behavioral ecology of entomopathogenic nematodes

“…Cruise foragers also respond to host contact cues. Lewis et al (1992) found that S. glaseri switched to localized search (e.g., speed decreased, distance traveled decreased, proportion of time spent moving decreased) after contact with then removal from host-associated cues (e.g., cuticle, feces). Localized search is thought to maximize the chance that a searcher will either remain in a potentially proWtable patch or reestablish contact with a host that was lost.…”

“…These behavioral mechanisms are consistent with the responses of a diverse range of cruise type foragers (Bell, 1991). Cruise foraging entomopathogenic nematode IJs move using relatively linear movement patterns that are typical of ranging search in the absence of host-associated cues (Lewis et al, 1992). Ranging movement is thought to maximize the area searched.…”

Movement of Heterorhabditis amazonensis and Steinernema arenarium in search of corn fall armyworm larvae in artificial conditions

“…These factors include soil characteristics (e.g., soil texture and moisture) (Kaya, 1990) and the infective juveniles search strategy ("ambush" versus "cruiser") (Lewis et al, 1992;Grewal et al, 1994). Accordingly, the objective of this study is to evaluate the movement of Heterorhabditis amazonensis RSC2 and Steinernema arenarium A11 in search of S. frugiperda.…”

Infectivity of Entomopathogenic Nematode, Steinernema carpocapsae, as Affected by the Emergence Time from the Host Cadaver

“…The present experiment also demonstrated the same morphological change; the later emergence from the cadavers of host insect, the more decreased in body length and width of the IJs. In addition to the above tendency, the decline of infective behaviors such as nictation (6,7,8,12), migration to host cue (7,11,13), penetration (connoted by mortality of host insects), or active dispersal movement (6,10) were accompanied by the delayed emergence. strategy (13).…”

“…In addition to the above tendency, the decline of infective behaviors such as nictation (6,7,8,12), migration to host cue (7,11,13), penetration (connoted by mortality of host insects), or active dispersal movement (6,10) were accompanied by the delayed emergence. strategy (13). As has been demonstrated, high nictation rates gave rise to high infectivity of the IJs (6, 12) through high migration and penetration rates (7 , 8).…”