Substrate and moisture affect pupation depth of the corn silk flies Chaetopsis massyla and Euxesta eluta (Diptera: Ulidiidae)

Authors: Allan, Sandra - Sandy

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2023
Publication Date: 10/28/2023
Citation: Allan, S.A. 2023. Substrate and moisture affect pupation depth of the corn silk flies Chaetopsis massyla and Euxesta eluta (Diptera: Ulidiidae). Insects. 14(11). Article number 838. https://doi.org/10.3990/insects14110838.
DOI: https://doi.org/10.3990/insects14110838

Interpretive Summary: One of the major pests of fresh market sweet corn production in tropical and semi-tropical regions are corn silk flies. These have been reported as particularly impactful in Argentina and southern and central Florida. Insecticides are used heavily to protect crops, however lapses in treatment or resistance can result in sufficient dam-age to render the cobs unmarketable. To provide better insight into development of alternative management strategies, research was conducted to better understand the pupation behavior of two major species of corn silk flies. In this study, a scientist at the USDA-ARS in Gainesville, Florida examined the effect of three soil types across six different levels of moisture to evaluate pupation behavior of the flies. Both soil and moisture levels impacted pupation depths and these factors are important for optimizing use of management strategies such as tilling or use of parasitoids as biological control agents

Technical Abstract: Corn silk flies or picture-winged flies (Diptera: Ulidiidae) are severe pests of fresh market sweet corn in commercial production areas in south Florida. Issues with pest management relating to insecticide resistance, problems in insecticide application and alternate crop population sources constitute a significant challenge for protection of developing corn ears. Developed larvae leave cobs and pupate in the soil, however relatively little is known about these behaviors. In this study, two soil types, collected from fields were compared to sand under 5 different moisture levels in the laboratory to determine pupation depths of the larvae. Comparisons were made with Chaetopsis massyla and Euxesta eluta and, two of the major pest species in Florida. Both soil type (muck, loamy sand and sand) and moisture levels (0, 10, 25, 50, 75, 100% field holding capacity) significantly affected pupation depth with shallow pupation under dry or saturated wet conditions. Addition of structure such as pipe cleaners simulating corn roots resulted in deeper pupation under most conditions.