Entomopathogenic Nematode Host-search Strategies

Entomopathogenic Nematode 2

Host-search Strategies

J.F. Campbell

1

and E.E. Lewis

2

(^1) Grain Marketing and Production Research Center, USDA-ARS,
1515 College Avenue, Manhattan, KS 66502, USA;^2 Department
of Entomology, Virginia Polytechnic Institute and State University,
Blacksburg, VA 24061, USA

Introduction

An organism’s foraging behaviour is a critical component of its life history

because acquisition of resources is closely linked with fitness, and

foraging mode can be correlated with a suite of ecological, behavioural,

physiological and morphological traits. The study of foraging behaviour

from both theoretical and empirical perspectives has been central to the

development of modern behavioural ecology (Stephens and Krebs, 1986;

Perry and Pianka, 1997). For most parasites, foraging for resources occurs

during two distinct phases: (i) the search for sites within a host by

parasitic stages; and (ii) the search for potential hosts by infective stages.

Parasitic stages of many species need to find suitable locations within a

host to feed, avoid host defences, locate mates or facilitate transmission

(Sukhdeoet al., Chapter 11, this volume). Parasites also need a mecha-

nism to bridge the gap between hosts. For many species, this mechanism

involves production of a free-living infective stage. Host finding by

infective stages may be passive (e.g. the infective stage is an egg) or active.

For those species with active free-living infective stages, proximate and

ultimate questions about their foraging behaviour can be addressed. In

this chapter, we focus on the diversity and sophistication of infective

juvenile host-search strategies of insect-parasitic nematodes.

Foraging Strategies

A number of conceptual models for the processes by which searchers

locate resources have been developed. Two broad categories of concep-

tual models are: (i) those that are based on the behavioural responses to

sequentially presented stimuli that vary in the quality of the information

CABInternational2002.The Behavioural Ecology of Parasites
(eds E.E. Lewis, J.F. Campbell and M.V.K. Sukhdeo) 13