Relationships between Volatile Organic Compounds Released by Wheat Plants Following Artificial Stress and Their Potential Influence on Natural Pest Management

Abstract

There is an urgent need to establish new agro-technical practices that require the delivery of effective, natural, ecological, and verified solutions. The evaluation of possible applications in the field of cropping and farming in recent years has resulted in numerous products and approaches, which may potentially reduce our dependence on artificial pesticides. A major requirement to help establish these new agro-technical practices is to determine their efficiency. Here we present a study that investigates the relationship between volatile organic compounds (VOCs) released by Triticum sp. plants under two artificial stress conditions. We discuss their effectiveness in natural pest management and for use in monitoring crop health. Two varieties of spring wheat, “Kandela” and “Serenada”, were exposed to either mechanical (deliberate) wounding, to imitate the stress caused by insect attack, or exposure to methyl jasmonate, a defence volatile used by plants. Both stress factors caused an increased release of green leaf volatiles (C6 aldehydes and alcohols) and other volatile compounds, such as (E)-β-ocimene, linalool, β-caryophyllene, and (E)-β-farnesene. VOC emission rates are reported at three time points (24, 48, and 72 h) following a stress factor. Correlation coefficients between the emitted plant’s VOCs indicate the potential of monitoring just one single compound from the combination of volatiles emitted by plants to predict the overall condition of a crop. This has major implications for the development of a chemically specific and fieldable analytical sensor that could be used to provide an array of volatile monitoring stations delivering information continuously and in real-time. Finally, we demonstrate the effectiveness of the volatiles released by damaged spring wheat for pest management by exposing a shield bug (Bishop’s Mitre (Aelia acuminata L.), Hemiptera: Pentatomidae), to them.