Identification of the sex pheromone of the tree infesting Cossid Moth Coryphodema tristis (Lepidoptera: Cossidae)

Marc Clement Bouwer; Bernard Slippers; Dawit Degefu; Michael John Wingfield; Simon Lawson; Egmont Richard Rohwer

doi:10.1371/journal.pone.0118575

Identification of the sex pheromone of the tree infesting Cossid Moth Coryphodema tristis (Lepidoptera: Cossidae)

PLoS One. 2015 Mar 31;10(3):e0118575. doi: 10.1371/journal.pone.0118575. eCollection 2015.

Authors

Marc Clement Bouwer¹, Bernard Slippers², Dawit Degefu², Michael John Wingfield², Simon Lawson³, Egmont Richard Rohwer⁴

Affiliations

¹ Department of Chemistry/Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, Gauteng, South Africa.
² Department of Genetics/Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, Gauteng, South Africa.
³ Department of Agriculture, Fisheries and Forestry/Ecosciences Precinct, University of the Sunshine Coast, Brisbane, QLD 4001, Australia.
⁴ Department of Chemistry/Center for Chromatography, University of Pretoria, Pretoria 0002, Gauteng, South Africa.

Abstract

The cossid moth (Coryphodema tristis) has a broad range of native tree hosts in South Africa. The moth recently moved into non-native Eucalyptus plantations in South Africa, on which it now causes significant damage. Here we investigate the chemicals involved in pheromone communication between the sexes of this moth in order to better understand its ecology, and with a view to potentially develop management tools for it. In particular, we characterize female gland extracts and headspace samples through coupled gas chromatography electro-antennographic detection (GC-EAD) and two dimensional gas chromatography mass spectrometry (GCxGC-MS). Tentative identities of the potential pheromone compounds were confirmed by comparing both retention time and mass spectra with authentic standards. Two electrophysiologically active pheromone compounds, tetradecyl acetate (14:OAc) and Z9-tetradecenyl acetate (Z9-14:OAc) were identified from pheromone gland extracts, and an additional compound (Z9-14:OH) from headspace samples. We further determined dose response curves for the identified compounds and six other structurally similar compounds that are common to the order Cossidae. Male antennae showed superior sensitivity toward Z9-14:OAc, Z7-tetradecenyl acetate (Z7-14:OAc), E9-tetradecenyl acetate (E9-14:OAc), Z9-tetradecenol (Z9-14:OH) and Z9-tetradecenal (Z9-14:Ald) when compared to female antennae. While we could show electrophysiological responses to single pheromone compounds, behavioral attraction of males was dependent on the synergistic effect of at least two of these compounds. Signal specificity is shown to be gained through pheromone blends. A field trial showed that a significant number of males were caught only in traps baited with a combination of Z9-14:OAc (circa 95% of the ratio) and Z9-14:OH. Addition of 14:OAc to this mixture also improved the number of males caught, although not significantly. This study represents a major step towards developing a useful attractant to be used in management tools for C. tristis and contributes to the understanding of chemical communication and biology of this group of insects.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Ectoparasitic Infestations*
Moths*
Sex Attractants*
Trees / parasitology*

Substances

Sex Attractants

Grants and funding

Members of the Tree Protection Co-operative Program (TPCP), the THRIP initiative of the Department of Trade and Industry and the DST/NRF Centre of Excellence in Tree Health Biotechnology (CTHB) are acknowledged for financial support. Grant 65891, National Research Foundation, http://www.nrf.ac.za/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.