Project: 2002-05. Report - Identification of the pheromone of the defoliator Pseudocoremia suavis (Lepidoptera: Geometridae)
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Date: 2004 Author: A.R. Gibb, D.M. Suckling, A. M. El-Sayed, B. Bunn, Publication: Report Project reference: 2002-05 Full report is available from: |
Executive summary:
This report summarises work undertaken in 2002–2004, for the New Zealand Forest Health Research Collaborative, to identify the sex pheromone of the common forest looper, Pseudocoremia suavis (Lepidoptera: Geometridae). Pseudocoremia suavis is a polyphagous native moth whose larvae also eat the leaves of Pinus radiata. In the past P. suavis has been responsible for major deforestation in P. radiata plantations notably at Eyrewell Forest, North Canterbury and in Kaingaroa Forest, Bay of Plenty.During 2002–2003 we identified four electrophysiologically active compounds in sex pheromone gland extracts of P. suavis, using coupled gas chromatography–electroantennogram detection (GC–EAD). Among these four antennally active compounds, two compounds consistently elicited a strong antennal response. However, preliminary analysis in 2002–2003, by coupled gas chromatography–mass spectrometry (GC–MS) to determine their chemical structure, indicated that the active compounds were present in relatively small amounts and therefore large numbers of moths would be required to obtain useful quantities, for any further qualitative analysis.
In December of 2003, when enough moths became available from a colony established at Forest Research, we analysed the pheromone gland extract by GC–MS. From mass spectral data obtained for three of the four active compounds, we established that the active compounds were most likely to be the unsaturated epoxides, (Z)–6–9,10–epoxynonadecene (active 1), (Z,Z)–3,6–9,10–epoxynonadecadiene (active 2) and (Z,Z)–3,6–9,10–epoxyheneicosadiene (active 4). Epoxides are known to be pheromones in the geometrid family and within the subfamily Ennominae, to which P. suavis belongs, nineteen carbon compounds are the most frequently occurring.
In 2004 the racemic form of (Z)–6–9,10–epoxynonadecene was synthesied by HortResearch chemists and a subsequent comparison of mass spectral data, has confirmed this compound as active 1. Similarly comparison of the mass spectra of active 4 with a racemic standard has established this active to be (Z,Z)–3,6–9,10–epoxyheneicosadiene. It is likely but not guaranteed that a synthetic blend of the two compounds eliciting the strongest antennal response (actives 1 and 2), will be enough for attraction of P. suavis males in the field. However, these types of compounds (epoxides) have chiral centres and therefore will have enantiomeric isomers, which may or may not be important to achieve an attractive blend capable of trapping male P. suavis on sticky bases, in delta pheromone traps within P. radiata plantations.
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It is expected that completion of this project will realistically require another 1–2 years and so further work will be undertaken as part of our FRST funded activity in the Biosecurity of New Zealand Forests programme.
Full report is available from:
HortResearch
Ruakura research Center
Private bag 3123
Hamilton
New Zealand
