Effects of diflubenzuron on Pseudoplusia includens (Lepidoptera : Noctuidae) and its parasitoid Copidosoma floridanum (Hymenoptera : Encyrtidae)

The insect growth regulator (IGR), diflubenzuron (Dimilin 2L), was evaluate d for its effect on development of Copiclosoma floridanum (Ashmead) and its host, Pseudoplusia includens (Walker), whet) applied at 0.035 kg ai/ha to soybean, Glycine max (L.), a rate used in preventive programs for control o f velvetbean caterpillar, Anticarsia gemmatalis Hubner. Parasitized and non parasitized soybean looper larvae were fed either diflubenzuron-treated of, nontreated foliage. The feeding period of parasitized larvae was 1.7 and 1 .8 d longer oil diflubenzitron-treated and nontreated foliage, respectively ,, than that of nonparasitized larvae. Pupation period of C, floridanum and soybean looper was not significantly influenced by diflubenzuron. Although parasitized soybean looper fed both foliage treatments experienced 100% mo rtality, nonparasitized soybean looper fed nontreated foliage was 23.2% and nonparasitized soybean looper fed diflubenzuron-treated foliage was 12.2%. Parasitized soybean looper fed nontreated foliage consumed 19.2% more leaf area than nonparasitized larvae fed nontreated foliage, whereas parasitize d soybean looper fed diflubenzuron-treated foliage consumed 21.2% more leaf area than nonparasitized larvae on the same foliage. There was no signific ant difference in number of parasitoids emerging from host mummies among tr eatments; however, there was a positive correlation between leaf area const rained and adult parasitoids per mummy. Diflubenzuron does not appear to pr oduce deleterious effects in C. floridanum of its host, soybean looper, at the current rate used for management of other lepidopteran pests.