Volatile extraction from soybean plants infested with several herbivores
The oral secretion of herbivores triggers chemical defenses in plants. When subjected to simultaneous or sequential attack by herbivores, plants emit volatile compounds of varying chemical nature, which can interfere with the attraction of natural enemies. This study investigates the profile of volatile compounds emitted by transgenic soybean (Bt M6210 IPRO) plants infested with Tetranychus urticae Koch (Acari: Tetranychidae) and Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae). To this end, we used a method without leaf maceration. For plant infestation, 100 T. urticae mites per plant were used for one day and, subsequently, 2 A. gemmatalis caterpillars for 36 hours. Volatile compounds produced after infestation were analyzed by gas chromatography coupled with mass spectrometry. Principal component analysis showed differences between groups of compounds and explained 77.5% of the variation in volatiles. There are chemical differences between the emission of compounds according to the type of herbivory. It is concluded that soybean plants infested in a single (T. urticae) or multiple (T. urticae followed by A. gemmatalis) way trigger the production of volatile compounds that can be used as chemical traces to direct the foraging of natural enemies. The possible functions of volatiles produced after herbivory are discussed.