Evaluation of Lures for Monitoring Silk Flies (Diptera: Ulidiidae) in Sweet Corn.

Several morphologically similar species of picture-winged flies (the silk fly complex, Diptera: Ulidiidae) are severe primary pests of sweet corn ( Zea mays L.; Poaceae) in Florida. Monitoring traps for these pests may aid threshold development and species complex determination in the field. This study evaluated floral lures, some previously used to monitor pest Lepidoptera, and liquid protein baits, used for other pest Diptera, for efficacy in attraction of silk flies. Baited universal moth traps were deployed for several weeks and placed in a summer fallow field (field trial 1), a fall sweet corn field (field trial 2), and a spring sweet corn field (field trial 3). Flies were removed weekly during each experiment. In field trial 1, traps baited with 1,4-dimethoxybenzene captured the most flies. The majority of flies captured were Chaetopsis massyla Walker. In field trial 2, aged torula yeast-baited traps captured more flies than other treatments, (1,4-dimethoxybenzene, geraniol, phenylacetaldehyde, and fresh torula yeast). The majority of captured flies were Euxesta stigmatias Loew. In field trial 3, the aged torula yeast treatment resulted in greater fly capture than all other treatments (1,4-dimethoxybenzene, acetoin, anisole, and benzaldehyde). Euxesta eluta Loew was the dominant species captured in the spring. More females than males were captured from all 3 experiments and all treatments. These experiments demonstrate that all 3 silk fly species can be captured in traps currently used for pest monitoring. Torula yeast was the best attractant evaluated, and further semiochemical investigations of torula yeast are warranted. [ABSTRACT FROM AUTHOR]