Performance of races of Bombyx mori L. under conditions temperature limits

Abstract

Two Bombyx mori L. races of chinese origin (C209, C122-B) and two races of japanese origin (M19-2, M12-B) were reared, from the 3º ínstar, in two conditions temperature limits (lower limit: temp. average of 20,21 ± 1,08°C and UR of 87,88 ± 6,12% and upper limit: temp. average of 30,50 ± 2,30°C and UR of 82,63 ± 9,37%), being the biological (duration of ínstars, mortality and weight gain) and productive (weights glands sericígenas, cocoon, cocoon shell and chrysalides) performance evaluated. The experimental design was completely randomized, in factorial scheme 2 x 4 (two conditions temperature limits x four races), with six replications for treatment. Caterpillars reared under temperature upper limit present shorter duration of ínstars and imcresed mortality, mainly at the end of larval period. The races C122-B and M19-2, obtained, in general, better performance when reared on condition temperature lower limit. Regarding the capacity of adaptation, under the conditions limits, highlights-if the race M12-B with one of the best performance productive.