Ecological fitting: Chemical profiles of plant hosts provide insights on selection cues and preferences for a major buprestid pest

Abstract

Specific cues used by emerald ash borer (EAB, Agrilus planipennis) to select hosts are largely unknown. Attractants are likely general and the use of novel host plants provides an opportunity to investigate the commonality of these cues. We examined volatile profiles emitted by five plants that can host EAB and estimated their importance in explaining known oviposition preferences.Foliage volatiles were collected from potted black ash (Fraxinus nigra), Manchurian ash (F. mandshurica), blue ash (F. quadrangulata), white fringetree (Chionanthus virginicus), and olive (Olea europaea) and analyzed using GC-MS.Fifty-nine compounds were detected including eight green leaf volatiles (GLV), 12 monoterpenes, and 21 sesquiterpenes. Ordination plots show separation of species by full foliage profiles, monoterpenes, sesquiterpenes, and known antennally active compounds, but GLVs were similar across hosts. Random Forest (RF) analysis revealed eight compounds that separated plant species with an error rate of ~19%, consisting mostly of sesquiterpenes.Similarity of GLV profiles among known hosts suggests they serve as general cues for host selection. Manchurian ash, a resistant host, produced the highest quantities and variety of sesquiterpenes indicating that some of these chemicals may be antixenotic. All compounds identified by RF have been implicated as deterrents or attractants to woodborers in other studies and should be investigated for adult antennal activity and attraction.