Location: Tropical Crop and Commodity Protection ResearchTitle: Evaluating Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) response to methyl eugenol: Comparison of three common bioassay methods
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2022
Publication Date: 3/17/2022
Citation: Sim, S.B., Curbelo, K.M., Manoukis, N., Cha, D.H. 2022. Evaluating Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) response to methyl eugenol: Comparison of three common bioassay methods. Journal of Economic Entomology. 115(2):556–564. https://doi.org/10.1093/jee/toac018.
Interpretive Summary: Methods for measuring insect behavior have been developed and are widely used. A common method for investigating insect response to a chemical attraction are lab-based olfactometers which can be controlled and executed with relative ease though are not as informative as field-based methods which can provide a more realistic view of insect behavior. Using the known behavior response of the Oriental fruit fly to the chemical attractant methyl eugenol (ME), we evaluated the effectiveness of three bioassay types, a rotating-carousel field cage, a small cage arena, and a Y-tube olfactometer to measure the attraction behavior of the Oriental fruit fly to ME and the effect of colony of origin and ME-feeding on attraction. These results have implications for olfactometer bioassay selection in entomological studies as well as impacts on pest management of the Oriental fruit fly.
Technical Abstract: 1. Behavior response of insects to olfactory stimuli is notoriously difficult to quantify. Though many types of laboratory assays exist to explore attraction, non-response, and repellence, their accuracy relative to each other and field experiments are usually not evaluated. 2. Using the Oriental fruit fly, Bactrocera dorsalis, its established attraction methyl eugenol (ME), and loss of attraction from ME feeding as a model, we compared the effectiveness of three commonly used bioassay methods that were used to measure lure response in Bactrocera flies under controlled conditions (choice assays using Y-tube [Y], small-cage arena [SC], and rotating carousel field-cage [RC]) to determine which bioassay method is the most efficient approach for reliable laboratory screening of ME non-responsiveness. 3. A series of bioassays comparing ME-fed and ME-naive wild-type and genetic sexing strain (GSS) males showed that the RC and SC bioassay methods were effective at both observing attraction to ME and detecting a significant reduction in ME response from ME exposed males. However, the male attraction to ME and a significant decrease in response to ME after ME feeding was not observed in our Y-tube assays. 4. Our results together suggest that RC and SC may be more viable bioassay options than Y-tube to evaluate ME non-responsiveness in GSS males. We further discuss practicality of administering different bioassays for this purpose as well as the implications of these results in the context of pest management.