A multiple-choice bioassay approach for rapid screening of key attractants from complex mixtures of fermentation volatiles

Authors: Cha, Dong; LOEB, GREGORY - Cornell University; Landolt, Peter; LINN, C - Cornell University; HESLER, STEVE - Cornell University

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2018
Publication Date: 4/13/2018
Citation: Cha, D.H., Loeb, G.M., Landolt, P.J., Linn, C.E., Hesler, S.P. 2018. A multiple-choice bioassay approach for rapid screening of key attractants from complex mixtures of fermentation volatiles. Environmental Entomology. 47(4):946-950. https://doi.org/10.1093/ee/nvy054.
DOI: https://doi.org/10.1093/ee/nvy054

Interpretive Summary: Volatiles produced by microbes attract a wide variety of insect pests and it is essential to identify key chemical attractants to develop efficient detection and mass trapping tools for integrated pest management. However, identification of actual chemicals responsible for the attraction has been traditionally challenging, and even daunting, as the development process is generally long and the outcome is often uncertain. Researchers at the USDA-ARS laboratory in Hilo,HI and Cornell University in Geneva,NY are developing a new laboratory bioassay approach that may expedite the process of the identification of a field-worthy attractant. By using a multiple-comparison bioassay approach, the authors could identify the two key attractants for spotted wing drosophila (acetoin and methionol) in one week, whereas it took two years of laboratory and field experiments to identify the two same attractants in previous studies. This novel bioassay approach provides new avenues of research to rapidly identify “field-worthy” behaviorally bioactive chemicals.

Technical Abstract: Fermentation volatiles are known to attract a wide variety of insects and thus useful for implementing integrated pest management programs. However, identification of the key behavior modifying chemicals has often been challenging due to the time consuming nature of thorough behavioral tests and, more severely, unexpected discrepancies between laboratory results and field trials. In this study, we report on a multiple-choice bioassay approach that may expedite the process of identification of a field-worthy attractant in the laboratory. Using the four-component key chemical blend (acetic acid, ethanol, acetoin and methionol) as the model, which was developed over 2-years in laboratory and field for Drosophila suzukii using wine and vinegar chemicals, we compared co-attractiveness of all of the 12 individual antennally active volatiles to a mixture of acetic acid and ethanol, known as the basal attractant for D.suzukii. In our laboratory test, only two compounds, acetoin and methionol, were co-attractive to a mixture of acetic acid and ethanol. The same result was also achieved when the 12 compounds were tested as two randomly selected groups. Comparison with previous published results revealed that the co-attractiveness of some of the 12 individual compounds including a key attractant, methionol, was different when they were tested using two- or multiple-choice assays, suggesting a role for background odor in the co-attractiveness of individual compounds. Our finding provides a potentially useful approach to identify behaviorally bioactive fermentation chemicals.