Variation in electrophysiological responses of Bracon cephi to the position of plant volatile collections from wheat plants infested with wheat stem sawfly, Cephus cinctus (Cephidae)
Oscar G. Pérez, email@example.com, David K. Weaver, firstname.lastname@example.org, Perry R. Miller, email@example.com, and Wendell L. Morrill, firstname.lastname@example.org. Montana State University, Land Resources and Environmental Sciences, Leon Johnson Hall. PO Box 173120, Bozeman, MT
Bracon cephi (Hymenoptera: Braconidae) is an effective parasitoid of wheat stem sawfly (Hymenoptera: Cephidae) larvae located cryptically within the stem of growing wheat plants. In an effort to better understand, and possibly enhance the ability of this parasitoid in detecting and suppressing this pest, studies were conducted on the variation of electrophysiological responses of B. cephi to chemical compounds produced by wheat plants infested with wheat stem sawfly. Experimental results suggest there are differences in the concentration of volatile compounds produced at different plant heights and that this parasitoid responds differently to these concentrations. Experiments were conducted under greenhouse conditions using ‘McNeal’ wheat plants. Wheat plants were infested by adult wheat stem sawflies and volatiles were collected from infested and control plants using a portable volatile collecting system. Volatiles were collected at three specific heights adjacent to the plants and were eluted and injected into a coupled gas chromatography - electroantennographic detection system to be analyzed by comparison to an internal standard. Individual compounds found in the collected blend of plant volatiles were also analyzed using an electroantennographic system. The electrophysiological responses of the parasitoids to the volatiles were scrutinized to assess if there is any variation in the response to compound concentration and compound type from each collection point. The results of these experiments will elucidate whether foraging parasitoids are more attracted to specific concentrations or type of compounds or to specific parts of the infested plant during host seeking, which may help in the enhancement of their performance as biocontrol agents.
Species 1: Hymenoptera Braconidae Braconcephi Species 2: Hymenoptera Cephidae Cephuscinctus (wheat stem sawfly)