Effects of Thermal Conditioning and of Degree of Saturation of Dietary Lipids on Resistance of an Insect to a High Temperature

The resistance of larvae of Pseudosarcophaga affinis (Fall.) to a high temperature was increased by thermal conditioning and by dietary lipids. The time of exposure to 45 °C required to cause 50% mortality of larvae reared at 23 °C on pork liver was 130 minutes (5% confidence limits 127 and 132 minutes). Pre-conditioning for 2 hours at 39 °C increased this time to 200 minutes (183 and 218 minutes). The time of exposure to 45 °C required to cause 50% mortality of larvae reared on chemically defined diets was 177 minutes (159 and 196 minutes) for those on a fat mixture that contained unsaturated fatty acids, 184 minutes (164 and 206 minutes) for those reared on an intermediate mixture, and 218 minutes (198 and 240 minutes) for those reared on a diet that contained a high proportion of saturated fatty acids. The degree of saturation of body lipids was directly influenced by the degree of saturation of the dietary lipids.