Abstract

Herbivorous insects face a dilemma when selecting suitable hosts in a complex environment, and their sensory capability may often reduce the female capacity for proper selection. As a consequence, eggs are often deposited on inferior hosts, affecting both insect and host plant fitness. We examined the attack rates of three cabbage herbivores in monocultures and biculture plots of different Brassica oleracea genotypes, with different spatial heterogeneity. The main goals of the study were to improve our understanding of the spatial scales involved in herbivore search processes and to examine the possibility of using spatial heterogeneity for manipulating pest attack rates in cabbage cropping systems. The results showed that the host selection behaviour of the small white butterfly (Pieris rapae) was strongly dependent on spatial heterogeneity. The difference in egg density between plant genotypes was larger when contrasting plants were growing in close proximity than in monoculture. This suggests that P. rapae is able to differentiate among genotypes from a small distance, while selection is compromised at larger spatial scales. The two other herbivores in the study (Mamestra brassicae and Delia radicum) did not respond to heterogeneity at any spatial scale, but showed a constant preference hierarchy. This suggests that host selection in these species occurs after direct plant contact. The difference in species' responses to spatial heterogeneity has consequences both for selection gradients in natural communities and for the potential to reduce pest attack in polyculture systems. (C) 2008 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

Keywords

Pieris rapae; Mamestra brassicae; Delia radicum; Searching behaviour; Brassica oleracea; Preference hierarchies; Cropping system; Herbivory

Published in

Basic and Applied Ecology
2009, Volume: 10, number: 3, pages: 228-236
Publisher: ELSEVIER GMBH, URBAN & FISCHER VERLAG

SLU Authors

• Rämert, Birgitta

  • Department of Plant Protection Biology, Swedish University of Agricultural Sciences
    

• Hopkins, Richard

  • Department of Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Horticulture
Environmental Sciences related to Agriculture and Land-use
Agricultural Science


Publication identifier

DOI: https://doi.org/10.1016/j.baae.2008.06.004

Permanent link to this page (URI)

https://res.slu.se/id/publ/49959