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Kehl, Alexandra ; Dötterl, Stefan ; Aas, Gregor ; Rambold, Gerhard:
Is flower scent influencing host plant selection of leaf-galling sawflies (Hymenoptera, Tenthredinidae) on willows?
In: Chemoecology.
Bd. 20
(2010)
Heft 3
.
- S. 215-221.
ISSN 1423-0445
DOI: https://doi.org/10.1007/s00049-010-0050-6
Abstract
Though it is known that flower scent not only attracts pollinators but also herbivores, little is known about the importance of flower scent on the distribution of leaf herbivores among individuals within a plant species. In this study we determined the distribution of galls induced by the sawfly Pontania proxima (Serville 1823) (Hymenoptera,Tenthredinidae, Nematinae) on flowering and nonflowering representatives of several clones belonging to Salix fragilis and S. 9 rubens (Salicaceae). Further, amounts and composition of scent of flowering and nonfloweringtwigs were compared (dynamic headspace-gaschromatography–mass spectrometry, DHS-GC–MS), and ascent sample collected from flowering twigs of S. fragilis was tested by coupled gas chromatography and electroantennographic detection (GC-EAD) on the antennae of P. proxima females. The results show that the presence off lower catkins on plants led to a higher degree of allocation with galls, but the number of galls differed not between flowering and non-flowering plants. The DHS-GC–MSanalyses revealed that the total amount of flower scentemitted per flowering twig is about 90 times higher than the scent emitted by a non-flowering twig. Further, several compounds were emitted only by flowering but not by nonfloweringtwigs. In the GC-EAD analyses, antennae consistently responded not only to green leaf volatiles, but alsoto compounds emitted only by the flowers (e.g. 1,4-dimethoxybenzene). These flower scent compounds are suggested to affect the host plant choice by attracting more sawflies from the distance to flowering plants compared to non-flowering plants. The EAD-active compounds emitted from vegetative plant parts are assumed to act as long distance signals especially when flowers are absent on hostplants, e.g. during the oviposition period of the second generation of P. proxima.