PRETREATMENT INDUCED THERMOTOLERANCE IN LIGHTBROWN APPLE MOTH (LEPIDOPTERA, TORTRICIDAE) AND ASSOCIATED INDUCTION OF HEAT-SHOCK PROTEIN-SYNTHESIS

The use of heat treatments for disinfestation purposes is becoming wid espread. The efficacy of such treatments may be influenced by exposure of insects to a range of temperatures in the environment before heat treatment disinfestation. We exposed 5th-instar light brown apple moth (Epiphyas postvittana Walker) to a range of temperatures and duration s in hot air before treatment, and examined the effects of these condi tions on mortality in a 43 degrees C hot-water treatment and on the in duction of heat Shock protein synthesis. Insect thermotolerance increa sed substantially with increased pretreatment temperature and duration ; the time until 99% mortality increased from 23.0 min with no pretrea tment, to 37.4 min after 8 h at 35 degrees C. Long periods at temperat ures before treatment as low as 28 degrees C increased thermotolerance , and periods as short as 15 min increased thermotolerance at higher t emperatures. Correlated with this increased thermotolerance was the de novo synthesis of several proteins observed by radiolabeling with [S- 35] methionine. Commercially available monoclonal antibodies of broad species cross reactivity to known heat shock proteins (HSP25, HSP60, H SP70, and HSP90) bound to constitutive forms of these proteins in West ern blots but were not induced as a result of heat pretreatment. A pro tein of M(r) 78 kDa was the predominant protein synthesized, which is in agreement with a recent report of a new class of heat shock protein s in the Lepidoptera. These data indicated that thermal conditions exp erienced by insects before disinfestation can greatly influence thermo tolerance.