ẢNH HƯỞNG CỦA NHIỆT ĐỘ, ẨM ĐỘ ĐẾN MỘT SỐ GIỐNG TẰM ĐA HỆ Ở THỜI KỲ TẰM LỚN

In the hot-humid (to>33oC, RH>90%), hot-dry (to>33o , RH90%) and colddry (to<20oC, RH <70%) conditions, silkworm was weak and infested by diseases. The yield and quality of cocoons and eggs also were reduced significantly. The resistance of silkworm to unfavorable conditions was dependence on race of silkworm and rearing conditions. The results indicated that when silkworm was reared in hot-humid and hot-dry conditions, the cocoon yields were decreased from 6 - 21 and 22 - 40%; and the percentage of clutch were reduced from 33 - 56 and 100%, respectively. In the cold-wet and cold-dry conditions, the cocoon yields were reduced from 3 - 7 and 32 - 51%, respectively. The ratios of standard eggs were reduced from 3 - 5 and 93 - 100% compared with that of the control. In both of hot-dry and cold-dry conditions, the rate of immerged cocoons and eggs were very low with inferior adhesion, unfertilized eggs. Among the tested 6 races of silkworm, TM, RVHT and VDK races had high resistant to hot and humid conditions of the summer.