Host finding behaviour as a predictor of foraging strategy in entomopathogenic nematodes

Abstract

SUMMARYForaging strategies of eight species of entomopathogenic nematodes were predicted from their response to host volatile cues and dispersal behaviour on 2-dimensional substrates. Positive directional response to chemical cues and similar distances travelled on smooth (agar) or nictation substrates (agar overlaid with sand grains) by Heterorhabditis bacterio-phora, Heterorhabditis megidis, Steinernema anomali, and Steinernema glaseri suggest their cruising approach to finding hosts. The absence of directional response and less distance travelled on nictation substrate, than on smooth agar by Steinernema carpocapsae and Steinernema 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 smooth agar; the two species also did not nictate. The cruiser species located hosts more effectively in the sand columns, whereas the ambushers were more effective at finding hosts on filter paper. Steinernema feltiae and Steinernema sp. performed equally on filter paper and in the sand column. We conclude that H. bacteriophora, H. megidis, S. anomali and S. glaseri cruise to find hosts, whereas S. carpocapsae and S. scapterisci ambush hosts. Steinernema feltiae and Steinernema sp. are intermediary in the search continuum sharing some characteristics of both ambush and cruise foragers.

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.…”

Simulated roots and host feeding enhance infection of subterranean insects by the entomopathogenic nematode Steinernema carpocapsae

“…The behavioural strategies employed by EPN species have been classified as being along a continuum from sedentary ambushers to more active cruising strategists (Campbell and Gaugler, 1997). Steinernema carpocapsae is classed as an ambush strategist, for which volatiles are unimportant in host-finding at a distance (Grewal et al, 1994;Lewis et al, 1995); most IJs remain near the soil surface (Georgis and Poinar, 1983) where they lift their body into the air in order to attach to a passing host (Campbell and Gaugler, 1993). Ambush strategists are considered to be more successful at infecting mobile, surface dwelling hosts; while cruisers are expected to infect less mobile hosts underground .…”

Serine Protease-mediated Host Invasion by the Parasitic Nematode Steinernema carpocapsae

“…The nematode infective juvenile (IJ) 6 is a resistant third juvenile that is free in the soil and seeks a suitable host in response to several cues, such as insect chemical and thermal signals (6). IJs enter the host through natural openings, mostly the mouth and anus, and cross the midgut to become established in the hemocoelium.…”