Epsilon Archive for Student Projects

Abstract

Aphid-plant interaction are complex processes where much still remains to be explored. This
project tested the capacity of aphid-infested barley, Hordeum vulgare (L.), to induce defencelike
responses in neighbouring plants via chemical signals, making them less acceptable to the
bird cherry-oat aphid Rhopalosiphum padi (L.). Chemicals released into the air or the
rhizospshere from infested plants can potentially act as defence-inducing signals in
neighbouring plants. Results showed that both volatiles and rhizospshere extracts from
infested plants can make receiving plants less acceptable to R. padi. Despite a range of
experiments, the decisive factors behind the rhizospshere interaction could not be identified;
however a hypothesis for future study is that soil micro-organisms play a role. Feeding by a
different aphid species, Myzus persicae (Sulzer), made barley plants more acceptable to R.
padi in settling tests. Aphids were attracted to the odour of M. persicae-infested plants and
settled more often on plants that had been exposed to M. persicae-infested plants. This
between-species interaction in aphids has not been previously reported. Further research is
needed to gain a deeper understanding of the importance of plant-plant chemical signalling in
aphid ecology, for example responses at the molecular level and effects on trophic
interactions. This project has however provided the first step for these investigations in this
study system.