Epsilon Open Archive

Abstract

There is extensive knowledge on the effects of insect herbivory on volatile emission from vegetative tissue, but little is
known about its impact on floral volatiles. We show that herbivory by phloem-feeding aphids inhibits floral volatile emission
in white mustard Sinapis alba measured by gas chromatographic analysis of headspace volatiles. The effect of the Brassica
specialist aphid Lipaphis erysimi was stronger than the generalist aphid Myzus persicae and feeding by chewing larvae of the
moth Plutella xylostella caused no reduction in floral volatile emission. Field observations showed no effect of L. erysimimediated
floral volatile emission on the total number of flower visits by pollinators. Olfactory bioassays suggested that
although two aphid natural enemies could detect aphid inhibition of floral volatiles, their olfactory orientation to infested
plants was not disrupted. This is the first demonstration that phloem-feeding herbivory can affect floral volatile emission,
and that the outcome of interaction between herbivory and floral chemistry may differ depending on the herbivore’s
feeding mode and degree of specialisation. The findings provide new insights into interactions between insect herbivores
and plant chemistry.