Volatile Compounds from the Bark Bugs Phloea subquadrata and Phloeophana longirostris (Heteroptera: Phloeidae)

Abstract

Phloea subquadrata and Phloeophana longirostris are subsocial species that differ from each other in their host plants and degrees of aggregation. Until recently, only ten low-molecular weight compounds, a sesquiterpene, and dimers of (E)-4-oxo-2-hexenal had been reported from the contents of P. subquadrata glands. Here, the main goal was to distinguish the volatile compounds released by adult males, adult females and nymphs of the two species. The analyses revealed 103 compounds, of which 44 were exclusive to Phloeophana longirostris and 15 were exclusive to Phloea subquadrata. The data were analyzed by chemometric methods, which discriminated the phloeid species by developmental stage and sex. (E)-2-Hexenal, (E)-4-oxo-2-hexenal and (E)-2-octenal were found in both species. Adult individuals were characterized by the presence of methyl 2-methylbutanoate, (E)-2-hexenyl acetate and 2-hexenyl butanoate, and nymphs were characterized by 5-ethyl-2(3H)-furanone and (E)-2-octenal. There was chemical distinction between volatiles of adults and nymphs of the two species studied.