Communication Between Undamaged Plants by Volatiles: the Role of Allelobiosis - Communication in Plants: Neuronal Aspects of Plant Life - page 432

suitable as a host. Aphids are well known for their capacity to detect and
use chemical indicators of plant condition, and can detect barley plants
that are engaged in allelobiosis with neighbouring plants, via volatile cues
before contacting the exposed plant itself. Owing to their sophisticated host
selection behaviour and mechanism of feeding, aphids represent an excel-
lent indicator of allelobiosis effects in plants, and future work will focus on
identifying the changes that occur in exposed plants, and their importance
for the herbivore as well as the plant itself. Ladybirds are polyphagous
predators, representing the third trophic level in the barley crop system.
The experimental results indicate that they respond positively to volatiles
released by barley exposed to allelobiosis from other plant species. This
supports the idea that the habitat-searching behaviour of adult ladybirds
is influenced by indicators of plant status, and contributes to understand-
ing of the mechanisms behind the effects of habitat diversity on natural
enemies of pests in managed systems.
Ecological and evolutionary understanding of allelobiosis is still at a very
early stage, and further knowledge of the potential benefits and costs to both
emitting and responding plants is necessary to understand the importance
of plant interactions of this type in natural and managed habitats. Deeper
understanding of how plants receive and translate volatile signals will lend
a fascinating perspective to research on the signalling systems involved.
The most exciting question will be to what extent allelobiosis represents
a source of information to the listening plant.
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