Feeding Behavior of Gypsy Moth (Lepidoptera: Lymantriidae) Larvae on Artificial Diet Containing Bacillus thuringiensis

The effects of Bacillus thuringiensis Berliner in artificial diet on the feeding behavior of lalvae of the gypsy moth, Lymontria dispar (L.), were measured in both short-term (1 d) and long-term (10 d) tests. In short-term tests, reduced rates of feeding, growth, and digestive efficiency were caused by B. thuringiensis at concentrations that did not kill larvae within the duration of the tests. In long-term tests, larvae given a choice between treated and untreated diets avoided diet containing B. thuringiensis for the first 7 d. After 7 d, increased movement by the larvae apparently obscured effects of B. thuringiensis on the distribution of the larvae. Effects of B. thuringiensis on the feeding behavior of gypsy moth larvae may, therefore, be one reason why high rates of mortality of gypsy moth are difficult to obtain with B. thuringiensis under field conditions.