Developmental Studies of Maize-Infesting Picture-Winged Flies (Diptera: Ulidiidae)

Eleven species of picture-winged flies (Diptera: Ulidiidae) attack maize (Zea mays L.) in the Americas. Field and laboratory studies were used to determine developmental times on sweet corn ears for the three most common species attacking the crop in the United States, Chaetopsis massyla (Walker), Euxesta eluta Loew, and Euxesta stigmatias Loew. Egg plus larval stage developmental times were evaluated in early Spring and late Fall 2009, and late Spring 2010, by placing newly deposited eggs in protected ears in the field. Newly formed puparia were removed daily from cages and held in the laboratory to determine pupal developmental times. Developmental times were compared with flies reared on artificial diet in the laboratory. Ear- and diet-reared adults were held until their death to determine adult longevity. Developmental times, including for pupae from ear-reared larvae, were significantly affected by species and season. All three species required nearly twice as long to complete development in the late Fall compared to late Spring studies. Flies required 3-13 d longer to complete development on artificial diet than on ears. Euxesta eluta adults lived two to three times longer than the other species, and females of all species lived 10-15% longer than males. Species and seasonal developmental times are discussed in relation to ear developmental times and control strategies. It is estimated that 16-19 generations per year of all three fly species can develop in the field in the sweet corn production area of southern Florida.