Effect of humidity condition on lifespan of short lifespan in imago strain of the silkworm, Bombyx mori

Lifespan in imago of the silkworm, Bombyx mori, is usually 4-8 days. We have three mutant strains whose moths survive 2 to 4 days only. We have suggested that water participated as one of the factors to the lifespan of imago in past studies. Therefore we investigated the influence of humidity on the lifespan of moth. The longest lifespan, 12.95 days, was observed at the intermediate humidity condition (76% R.H.) in the control strain, N17, as compared with 8.84 days at low humidity condition (21% R.H.) and 7.50 days at high humidity condition (96% R.H.). On the other hand, 5.22days of the longest lifespan was observed at high humidity condition (96% R.H.) in the short lifespan strain, N25, as compared with 3.42 days at 74% R.H. and 2.71 days at low humidity condition (21% R.H.). Thus, it was cleared that the lifespan of the moths in the strain of short lifespan imagoes were extended by preservation at high humidity and were shortened at low humidity.