FEEDING-BEHAVIOR OF GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) LARVAE ON ARTIFICIAL DIET CONTAINING BACILLUS-THURINGIENSIS

The effects of Bacillus thuringiensis Berliner in artificial diet on t he feeding behavior of larvae of the gypsy moth, Lymantria dispar (L.) , were measured in both shortterm (1 d) and long-term (10 d) tests. In shelf-term tests, reduced rates of feeding, growth, and digestive eff iciency were caused by B. thuringiensis at concentrations that did not kill larvae within the duration of the tests. In long-term tests, lar vae given a choice between treated and untreated diets avoided diet co ntaining B. thuringiensis for the first 7 d. After 7 d, increased move ment by the larvae apparently obscured effects of B. thuringiensis on the distribution of the larvae. Effects of B. thuringiensis on the fee ding behavior of gypsy moth larvae may, therefore, be one reason why h igh rates of mortality of gypsy moth are difficult to obtain with B. t huringiensis under field conditions.