BEHAVIORAL-RESPONSES OF LIGHTBROWN APPLE MOTH NEONATE LARVAE ON DIETSCONTAINING BACILLUS-THURINGIENSIS FORMULATIONS OR ENDOTOXINS

Behavioral responses of individual lightbrown apple moth, Epiphyas pos tvittana (Walker), neonate larvae to Dipel or the Bacillus thuringiens is delta endotoxins CryIAc and CryIBa incorporated into artificial die ts were measured in choice and no-choice treatments. Frass production and the spinning of silken shelters were delayed when larvae were give n diets containing Dipel or Bt endotoxins. In choice treatments larvae did not exhibit an initial preference for control diets over diets wi th Dipel or Bt endotoxins but accumulated on control diets over a peri od of days, apparently because larvae that first settled on Dipel or e ndotoxin diets abandoned diets while larvae that fed on control diets remained on diets throughout the experiment. Abandonment of diets cont aining Dipel or endotoxins was also apparent in no-choice treatments. Larvae exposed to such diets were more likely to be observed walking o r at different sites from one observation to the next, and produced fr ass and silken feeding shelters at multiple sites rather than a single site. The implications of these findings for the use of B. thuringien sis as a commercial spray or for the use of B. thuringiensis endotoxin genes as resistance factors to be expressed in transgenic apples are discussed.