Relationship between Thermotolerance and Heat-stable Esterase in the Silkworm, Bombyx mori(Lepidoptera:Bombycidae)

Abstract

Thermotolerance of the silkworm, Bombyx mori L., varied with strains when reared at 28°C and 34°C, 70-85% RH for 12 h. The thermotolerance was positively relative to the activity of a hear-stable esterase (Hs EST) analyzed in larval body or midgut. This enzyme activity could be adopted as an indicator for the silkworm thermotolerance. Zymograms showed that an E5 band in midgut preparations is predominant and is thus related to thermotolerance. The activity of Hs EST, especially E5, increased with hear selection for 7 generations, indicating that this enzyme seems to be induced by rearing the silkworms under high temperatures.