Comparison of volatile emissions from undamaged and mechanically damaged almonds

BACKGROUND: The navel orangeworm (NOW) Amyelois transitella (Walker) is a major insect pest of almonds causing considerable monetary setbacks for both growers and processors, and thus control of NOW is one of the top priorities for the almond industry. Field observations purport that NOW is attracted to previously injured almonds. Accordingly, in this study the volatile output of damaged almonds was investigated in an effort to identify potential attractants for further studies into the control and/or monitoring of NOW. Mature almonds from the Monterey variety were evaluated for their volatile composition after mechanical damage and compared with the volatile composition of undamaged almonds. RESULTS: Volatile organic compounds (VOCs) were collected on Tenax, desorbed and identified via gas chromatography/mass spectrometry analysis. VOCs unique to the damaged tree nuts included trace amounts of 3-pentanol and isomers of the spiroketal chalcogran. VOCs that increased in relative amounts after damage include the spiroketal conophthorin and numerous four-carbon ester and ketone as well as alcohol derivatives, in addition to two eight-carbon chain compounds. CONCLUSION: Several VOCs, both unique and in increased amounts, were identified from damaged almonds. Their presence in damaged almonds warrants further investigation into their role in NOW response to damaged almonds, which may lead to insights into the control and/or monitoring of NOW. Published in 2008 by John Wiley & Sons, Ltd.