Herbivore‐induced volatiles influence moth preference by increasing the β‐Ocimene emission of neighbouring tea plants

Herbivore‐induced plant volatiles prime neighbouring plants to respond more strongly to subsequent attacks. However, the key volatiles that trigger this state and their priming mechanisms remain largely unknown. The tea geometrid Ectropis obliqua is one of the most devastating leaf‐feeding pests of tea plants. Here, plant–plant communication experiments demonstrated that volatiles emitted from tea plants infested by E. obliqua larvae triggered neighbouring plants to release volatiles that repel E. obliqua adult, especially mated females. Volatile analyses revealed that the quantity of eight volatiles increased dramatically when plants were exposed to volatiles emitted by infested tea plants, including (Z)‐3‐hexenol, linalool, α‐farnesene, β‐Ocimene and (E)‐4,8‐dimethyl‐1,3,7‐nonatriene (DMNT). The results of behavioural bioassays demonstrated that β‐Ocimene strongly repelled mated E. obliqua females. Individual volatile compound exposure experiments revealed that (Z)‐3‐hexenol, linalool, α‐farnesene and DMNT triggered the emission of β‐Ocimene from tea plants. Chemical inhibition experiments demonstrated that the emission of β‐Ocimene induced by (Z)‐3‐hexenol, linalool, α‐farnesene and DMNT were dependent on Ca2+ and JA signalling. These findings help us to understand how E. obliqua moths respond to volatiles emitted from tea plants and provide new insight into volatile‐mediated plant–plant interactions. They have potential significance for the development of novel insect and pest control strategies in crops. Herbivore‐induced plant volatiles (HIPVs) play important ecological roles in defense against stresses and prime neighboring intact plants to respond more strongly to subsequent attacks. However, the key volatiles that trigger this primed state and their priming mechanisms remain largely unknown. Here, plant–plant communication experiments demonstrated that volatiles emitted from tea plants infested by Ectropis obliqua larvae triggered neighboring intact plants to release volatiles that repel E. obliqua mated females. The results of behavioral bioassays demonstrated that β‐Ocimene strongly repelled mated E. obliqua females. Here, we provide the first evidence for the HIPVs triggered the emission of β‐Ocimene from the primed plants. Chemical inhibition experiments demonstrated that the emission of β‐Ocimene induced by these volatiles was dependent on Ca2+ and JA signaling in primed plants. The knowledge will help us to understand how E. obliqua female m