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. erysimi-mediated 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.
Highlights
Volatile organic compounds emitted from plants mediate an array of ecological interactions
The compounds most associated with P. xylostella damage were benzyl alcohol, benzyl acetate and vanillin, whereas the compound most associated with M. persicae damage was panisaldehyde
We found that (i) herbivory by aphids inhibits the production of floral volatiles in S. alba, (ii) the inhibition was not caused by a chewing herbivore and was more pronounced in a specialist aphid than in a generalist, (iii) inhibition of floral volatile production did not have a major disruptive effect on pollinator visitation or on olfactory orientation of the aphids’ natural enemies
Summary
Volatile organic compounds emitted from plants mediate an array of ecological interactions. They play important roles in plant defence as herbivore deterrents [1,2,3] and in the attraction of predators and parasitoids to herbivore damaged plants [for reviews see 4,5]. Volatiles emitted from flowers play a vital role in mediating the mutualism between plants and their pollinators [6]. For many years pollination ecology and plant defence were studied separately [7], as adaptations to distinct and independent selective pressures. Floral volatiles have the potential to mediate interactions of plants with pollinators, but a series of direct and indirect interactions with other organisms such as herbivores, predators and microorganisms [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
