Time-resolved characterization of biotic stress emissions from Scots pines being fed upon by pine weevil by means of PTR-ToF-MS

Insect herbivory of plants leads to the increased emissions of highly reactive volatile organic compounds (VOCs). We measured above-ground VOC emissions of Scots pine (Pinus sylvestris) saplings in the laboratory using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) before, during and after a 48-hour exposure to bark-feeding pine weevils. This study provides an in-depth investigation of the whole-plant VOC emission profile and its changes due to pine weevil feeding with a high time resolution. Monoterpenes dominated the emissions during and after herbivore feeding. The average monoterpene emission rate increase due to pine weevil feeding was 90 times and maximum monoterpene emission response was linearly proportional to the damaged bark area, demonstrating a dose-dependent response. Overall, the emission rates of more than ten VOC groups were increased due to herbivore feeding. These results increase knowledge about the effect of bark-feeding herbivores on VOC emissions from conifer forests and shed light on the important influence of herbivore ecosystem disturbance on atmospheric chemistry.