Spectral sensitivity and color discrimination of Euxesta eluta and Chaetopsis massyla Diptera:Ulidiidae)

Authors: Allan, Sandra

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2026
Publication Date: 4/3/2026
Citation: Allan, S.A. 2026. Spectral sensitivity and color discrimination of Euxesta eluta and Chaetopsis massyla Diptera:Ulidiidae). PLOS ONE. https://doi.org/10.1371/journal.pone.0346423.
DOI: https://doi.org/10.1371/journal.pone.0346423

Interpretive Summary: Fresh market sweet corn production in Florida is threatened by larval infestations of the corn silk flies, Euxesta eluta and Chaetopsis massyla (Diptera: Ulidiidae). Control of these flies is primarily by insecticide application, however standardized surveillance methods are lacking and the lack of information about the vision of these flies limits development of visual traps. In this study, a scientist with the USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, electrophysiologically examined visual responses of the two fly species. Visual sensitivity could be explained by the presence of ultraviolet, blue, green and yellow photopigments. In a field trial, responses were greatest to yellow and yellow-green traps and these studies provide the basis for development of a visually-based surveillance method for these flies.

Technical Abstract: Fresh market sweet corn production in Florida is threatened by the corn silk flies, Euxesta eluta Loew and Chaetopsis massyla Walker (Diptera: Ulidiidae). Using electroretinograms, the spectral sensitivity curves for both species revealed broad curves with a peak in the UV (350 nm) and the green region (500-550 nm) of the spectrum. Curves for males and females of each species were relatively similar in shape. Using pigment templates, the measured curve for E. eluta was matched by pigment combinations with maximum sensitivity at 350, 430, 500 and 560 nm in a ratio of 25:21:25:29. Similarly, the curve for C. massyla was best matched by pigments with maximum sensitivity at 350, 430, 500 and 560 nm in a 28:18:27:27 ratio. In a field study in north central Florida, trap collection consisted primarily of C. massyla (98.11%) with relatively few E. eluta (1.89%) collected. The collections of C. massyla were highest to traps that were yellow, yellow green and orange, followed by green, white, and then blue and black. Too few E. eluta were collected to make color comparisons.