Flexibility in Host-search and Patch-use Strategies

Flexibility in Host-search and 3

Patch-use Strategies of Insect

Parasitoids

Louise E.M. Vet,

1, 2

Lia Hemerik,

3

Marcel E. Visser

1

and Felix L. Wäckers

1, 2

(^1) Netherlands Institute of Ecology, Centre of Terrestrial Ecology,
Heteren, The Netherlands;^2 Laboratory of Entomology, Wageningen
University, PO Box 8031, 6700 EH Wageningen, The Netherlands;
(^3) Biometris, Department of Mathematical and Statistical Methods,
Wageningen University, Wageningen, The Netherlands

Introduction

Parasitoids, typically parasitic wasps, deserve to be the subject of

a(nother) book, not a chapter. Anyone who has ever watched a searching,

egg-laying or feeding parasitoid has fallen in love with the beauty of these

elegant and often colourful insects. But, then again, some people may be

disturbed by their gruesome life history. After all, these lovely parasitoids

are insects that lay their eggs in or on other insects. The parasitoid larva

feeds on the body of the victim, euphemistically called the host insect,

which is eventually killed. A dying caterpillar with parasitic larvae crawl-

ing out of its body is perhaps too much hard-core biology for some people.

So we restrict ourselves to a chapter on insect parasitoids, with a

focus on flexibility in their host-search and patch-use strategies. For

extensive reviews on the ecology and life history of insect parasitoids, we

refer to the excellent books by Askew (1971) and especially Godfray

(1994) – a ‘must’ if you catch some of our enthusiasm for these fascinating

creatures.

The majority of parasitoids belong to the Hymenoptera and Diptera.

The parasitic habit has most probably evolved from the predatory lifestyle

of ancestral species that ate dead or living insects. Through their intimate

relationship with their hosts, evolution has led to explosive speciation

and adaptive radiation in the way parasitoids locate, parasitize and

develop in other insects. Their diversity in exquisite, often weird life-

styles and their adaptive behaviour are overwhelming and probably

unequalled in the animal world. In addition to being interesting objects

for fundamental biological study, parasitoids are economically and

ecologically very important insects. In agricultural systems they play a

CABInternational2002.The Behavioural Ecology of Parasites
(eds E.E. Lewis, J.F. Campbell and M.V.K. Sukhdeo) 39