Attraction, oviposition preferences, and olfactory responses of corn-infesting Ulidiidae (Diptera) to various host-based substrates

Authors: OWENS, DAVID - University Of Florida; NUESSLEY, G.S - University Of Florida; Kendra, Paul; COLQUHOUN, T. A. - University Of Florida; SEAL, D. R. - University Of Florida

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2017
Publication Date: 8/1/2017
Citation: Owens D., Nuessly, G.S., Kendra, P.E., Colquhoun, T.A., Seal, D.R. 2017. Attraction, oviposition preferences, and olfactory responses of corn-infesting Ulidiidae (Diptera) to various host-based substrates. Environ. Entomol. 46(4): 885-894.

Interpretive Summary: Several species of corn-silk fly (Diptera: Ulidiidae) are serious economic pests of sweet corn in Florida, a market valued at $155 million per year. Currently, no standard lure exists for monitoring these pests, and detection is accomplished by scouts that routinely inspect the fields for pest presence, which then prompts pesticide applications. Scientists from the University of Florida and the USDA Agricultural Research Service (Miami, FL) initiated research to identify the first attractants for these pests. Substrates evaluated included corn silk, corn tassel, corn pollen, and frass from the fall armyworm (another pest of corn) that was fed various tissues from corn plants. Of these substrates, the armyworm frass was shown to emit the strongest volatile attractants for silk flies, and it also resulted in the highest number of eggs laid. These results indicate that armyworm frass is an important resource in the chemical ecology of silk flies, and it is the most promising substrate for identification of chemical attractants that can be used to develop field lures for silk flies. Availability of an effective lure would provide early pest detection, and reduce the need for chemical insecticides.

Technical Abstract: Fresh market sweet corn produced in Florida is threatened by larval damage by Euxesta stigmatias Loew, E. eluta Loew, and Chaetopsis massyla Walker (Diptera: Ulidiidae) that renders ears unmarketable. No standard lure exists for monitoring these pests. Oviposition and attraction bioassays were designed to identify attractive substrates for further semiochemical investigation. The most promising substrates were then evaluated by electroantennography (EAG) to quantify olfactory responses. Frass from fall armyworm, Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), was more attractive than other ovipositional substrates tested for two fly species, and resulted in greater ovipositional output. Tassel-derived armyworm frass was more attractive than leaf-derived frass for oviposition. Frass also resulted in greater oviposition output by two species. In attraction bioassays, frass was generally preferred over the corresponding corn tissue, and only C. massyla demonstrated a preference for silk-frass over tassel-frass. Frass volatiles also elicited greater antennal responses than corn volatiles. With tassel-frass, greater amplitude EAG responses were recorded from immature E. eluta female antennae, but E. stigmatias exhibited greater responses from mature females. Equivalent antennal response to silk-frass was observed from E. eluta. Our results indicate that armyworm frass is an important resource in the chemical ecology of corn-infesting silk flies, and this substrate warrants further investigation for potential attractants that may facilitate development of novel management tools for these pests.