Effects of diet ingredient source and preparation method on larval development of laboratory-reared gypsy moth (Lepidoptera: Lymantriidae)

We compared diet ingredient source (vendor or batch) and preparation methods used at 2 gypsy moth, Lymantria dispar L., rearing facilities in 2 rearing environments to identify the dietary variable that results in unpredictable periods of slow, asynchronous larval development. The mean instar at 10 d was used to assess the larval development in these experiments. Wesson salt mixture (mineral supplement) from 1 of the 2 vendors used was found to cause slow, asynchronous development. The particular batch of wheat germ, casein, and vitamin mixture used was found to influence the rate of larval development. The method of diet production interacted with the diet ingredients to influence the rate of larval development, but the source of the diet ingredients methyl parahydroxybenzoate, sorbic acid, and agar had no effect. How mineral components of the diet can affect larval development, and the importance of quality control in artificial diet, are discussed.