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Does enemy-free space for eggs contribute to a leaf beetle's oviposition preference for a nutritionally inferior host plant?
Auteur(s)
Date de parution
2001
In
Functional Ecology, Wiley, 2001/15/3/318-324
Résumé
<b>1.</b> Natural enemies are likely to influence the interactions between herbivorous insects and their host plants. In particular, selection exerted by natural enemies could favour host-plant switches and cause, or maintain, oviposition preference for a host species that is nutritionally inferior to another acceptable host. <br> <b>2.</b> In a previous study, it was shown that larvae of the leaf beetle <i>Oreina elongata</i> perform better on <i>Adenostyles alliariae</i> (Asteraceae) than on <i>Cirsium spinosissimum</i> (Asteraceae). Moreover, <i>A. alliariae</i> provides larval and adult beetles with sequestrable chemical defences. However, in the field, egg densities are much higher on <i>C. spinosissimum</i> than on adjacent <i>A. alliariae</i>. <br> <b>3.</b> In this study, it was investigated whether this oviposition pattern could be maintained by <i>C. spinosissimum</i>, providing the eggs of <i>O. elongata</i> with better protection from natural enemies. In a field experiment, the survival of eggs was quantified on plants of each of the two species, with and without enemy exclusion. <br> <b>4.</b> Egg survival was equal for both host species when enemies were excluded from the plants, but it was higher on <i>C. spinosissimum</i> than on <i>A. alliariae</i> when enemies were allowed to the plants. It was also experimentally tested whether the higher egg densities observed in the field on <i>C. spinosissimum</i> are actually due to oviposition preference by the beetle. In a no-choice test, females laid more eggs on <i>C. spinosissimum</i> than on <i>A. alliariae</i>. <br> <b>5.</b> It can thus be confirmed that <i>C. spinosissimum</i> is really preferred for oviposition and it is concluded that this preference is likely to be maintained, at least partly, by a higher egg survival on <i>C. spinosissimum</i> due to enemy-free space provided by this host plant.
Identifiants
Type de publication
journal article
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