This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.
Electroantennogram Responses of Six Bactrocera and Zeugodacus spp. to Raspberry Ketone Analogs
The Queensland fruit fly (Bactrocera tryoni, Q-fly) is a major horticultural pest in eastern Australia. The deployment of male lures comprises an important component of several detection and control strategies for this pest. A novel fluorinated analog of raspberry ketone (RK), raspberry ketone trifluoroacetate (RKTA), has been developed with the aim of further improving Q-fly control. RKTA elicited strong electroantennogram (EAG) responses from Q-flies while cuelure (CL) and melolure (ML) responses were not significantly greater than a negative control. Further experimentation showed that RKTA also elicited EAG response from five other fruit fly spp., included flies known to be strongly attracted to CL (B. neohumeralis, B. kraussi, and B. frauenfeldi), weakly attracted to CL (B. jarvisi), or nonresponsive to CL (Zeugodacus cucumis), while seven other compounds, RK, CL, ML, raspberry ketone difluoroacetate, raspberry ketone monofluoroacetate, anisyl acetone, and trimethylsilyl raspberry ketone, elicited only weak responses comparable to a negative control. However, fly EAG responses to RKTA are likely due at least in part to trifluoroacetic acid, which is a hydrolysis product of RKTA and elicited strong EAG responses from all six spp. when tested alone. Furthermore, while acetic acid, formic acid, and trifluoroacetic acid all elicited strong EAG responses in Q-flies, the only corresponding RK ester to elicit an EAG response was RKTA, suggesting that RKTA hydrolyses quickly, while CL and ML do not. This is in contrast to the idea that CL readily hydrolyses on contact with atmospheric moisture, an assertion that has been stated in the literature repeatedly.
EN17091 Accepted 06 July 2017
© CSIRO 2017