GYPSY-MOTH (LYMANTRIA-DISPAR) LARVAL DEVELOPMENT AND SURVIVAL TO PUPATION ON DIET PLUS EXTRACTABLES FROM GREEN ASH FOLIAGE

Gypsy moth, Lymantria dispar L., rate of larval development, molting, pupal weight and survival were studied on an artificial diet containin g different concentrations of green ash ethyl acetate extractables (Et OAc Errs). Insects were reared on experimental diets from egg to pupa. Addition of EtOAc Exts to artificial diet significantly prolonged lar val development and reduced their survival compared to larvae reared o n control diet. Weights of pupae were significantly reduced when larva e were reared on diet containing the lowest dosage of EtOAc Exts (i.e. , 0.01%) versus on control diet. EtOAc Exts in diet (e.g., 0.01, 0.06 and 0.24%) frequently caused incomplete ecdysis which invariably resul ted in larval death. Impaired feeding, locomotion and excretion are li kely causes of death. The combination of these results with our earlie r findings of repellents and feeding deterrents against gypsy moth lar vae (GML) in green ash foliage shows that the non-host status of green ash to the highly polyphagous GML involves three orders of chemical d efense: repellents, feeding deterrents and inhibitors of nutritional a nd developmental physiology. As the insect becomes sequentially expose d to these orders of defense, it incurs higher costs because the adver se effects become less reversible.