Identification of the Sex Pheromone of the Tree Infesting Cossid Moth Coryphodema tristis (Lepidoptera: Cossidae)

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.

[1]  T. Nakanishi,et al.  Female Sex Pheromone of a Carpenter Moth, Cossus insularis (Lepidoptera: Cossidae) , 2006, Journal of Chemical Ecology.

[2]  M. Konstantopoulou,et al.  Efficient Mass-Trapping Method As an Alternative Tactic for Suppressing Populations of Leopard Moth (Lepidoptera: Cossidae) , 2009 .

[3]  J. Millar,et al.  Kováts Retention Indexes of Monounsaturated C12, C14, and C16 Alcohols, Acetates and Aldehydes Commonly Found in Lepidopteran Pheromone Blends. , 2000 .

[4]  B. Hansson,et al.  Comparison of male and female olfactory cell response to pheromone compounds and plant volatiles in the turnip moth, Agrotis segetum , 1989 .

[5]  D. H. Slone,et al.  An Automated Approach to Detecting Signals in Electroantennogram Data , 2007, Journal of Chemical Ecology.

[6]  S. Schulz,et al.  Autodetection and chemistry of female and male pheromone in both sexes of the tiger moth Panaxia quadripunctaria , 1998, Journal of Comparative Physiology A.

[7]  Responses of three antennal specialist neurons of male Trichoplusia ni (Hübner) to sex pheromone components at and above naturally emitted levels , 1993 .

[8]  S. Ramaswamy,et al.  Biology and ultrastructure of sex pheromone-producing tissue , 2003 .

[9]  R. Vogt,et al.  Insect pheromone biochemistry and molecular biology : the biosynthesis and detection of pheromones and plant volatiles , 2003 .

[10]  D. Schneider.  Elektrophysiologische Untersuchungen von Chemo- und Mechanorezeptoren der Antenne des Seidenspinners Bombyx mori L. , 2004, Zeitschrift für vergleichende Physiologie.

[11]  D. Struble,et al.  Combined Gas Chromatography and Electroantennogram Recording of Insect Olfactory Responses , 1984 .

[12]  Michael J. Wingfield,et al.  A new lepidopteran insect pest discovered on commercially grown Eucalyptus nitens in South Africa , 2005 .

[13]  SEX PHEROMONE COMPONENTS OF THE SANDTHORN CARPENTERWORM, Holcocerus hippophaecolus , 2005, Journal of Chemical Ecology.

[14]  H. Buser,et al.  Determination of double bond position in mono-unsaturated acetates by mass spectrometry of dimethyl disulfide adducts , 1983 .

[15]  G. Guglielmetti,et al.  Sex pheromone components of the European goat moth,Cossus cossus , 1983, Journal of Chemical Ecology.

[16]  A. J. Meyer.  A histological study of the alimentary canal and associated structures in the larva of Coryphodema tristis Drury (Lepidoptera) , 1965 .

[17]  R. Jurenka.  Biochemistry of female moth sex pheromones , 2003 .

[18]  R. Mankin,et al.  Quantitation of the insect electroantennogram: Measurement of sensillar contributions, elimination of background potentials, and relationship to olfactory sensation , 1984 .

[19]  Ring T. Cardé,et al.  CONTROL OF MOTH PESTS BY MATING DISRUPTION: Successes and Constraints , 1995 .