Ozone alters the feeding behavior of the leaf beetle Agelastica coerulea (Coleoptera: Chrysomelidae) into leaves of Japanese white birch (Betula platyphylla var. japonica)

Abstract

High mixing ratios of ground-level O₃ threaten trophic interactions. In the present study, we conducted laboratory assays, where insect larvae and adults were not directly exposed to O₃, to test the feeding behavior and attraction of the coleopteran leaf beetle Agelastica coerulea to early and late leaves of Japanese white birch (Betula platyphylla var. japonica) treated with ambient or elevated O₃ levels. We found that overwintered adults were not deterred from grazing elevated O₃-treated leaves, but rather preferred them than ambient O₃-treated ones. We also found that the feeding behavior of 2nd instar larvae fed on early or late leaves was not influenced by the O₃ treatment of the leaves when larvae could choose leaves. These observations of the adults and larvae feeding preferences contradict prior observations in the field conditions where the insects avoided leaves in O₃-enriched atmosphere. Since adults preferred elevated O₃-exposed leaves in the present laboratory assays, it is worthy of further investigations whether adults change their grazing preference so as to ensure the leaf palatability as a feeding source for their larvae. Hence, new direction towards detailed ovipositional behavior surveys under field conditions is encouraged.

Keywords: Adult; Feeding; Herbivory; Insect grazing; Larva; Phytophagous insect; Trophic interaction; Tropospheric O3.