Permalink : http://hdl.handle.net/2115/84959

JaLCDOI : 10.14943/EJFR.22.63

KEYWORDS : atmospheric lifetime;biogenic volatile organic compounds (BVOCs);herbivorous insects;olfactory response;ozone

Elevated ground-level ozone (O3) reduced C-based defense chemicals; however, severe grazing damages were found in leaves grown in the low O3 condition of a free air O3-concentration enrichment system. To explain this phenomenon, this study investigates the role of BVOCs (Biogenic Volatile Organic Compounds) as signaling compounds for insect herbivores. BVOCs act as scents for herbivore insects to locate host plants, while some BVOCs show high reactivity to O3, inducing changes in the composition of BVOCs in atmospheres with elevated O3. In this study, profiles of BVOCs emitted from birch (Betula platyphylla var. japonica) leaves were analyzed, and Y-tube insect preference tests were conducted to study the insect olfactory response. The assays were conducted in June and August or September, according to the life cycle of the adult alder leaf beetle Agelastica coerulea. The Y-tube tests revealed that the leaf beetles were attracted to BVOCs, and O3 per se had neither an attractant nor a repellent effect. BVOCs became less attractant when mixed with highly concentrated O3 (>80 ppb). About 20% of the total BVOCs emissions were highly O3-reactive compounds, such as β-ocimene. The results suggest that BVOCs emitted from the birch leaves can be altered by elevated O3, and, thus, potentially reducing the attractiveness of leaves to herbivorous insects searching for food.