Effects of different rearing temperature on sex ratio and eclosion of Diadegma semiclausum Hellén
Author of the article:LI XY，YING YQ，ZHAO XQ，CHEN AD
Author's Workplace：Institute of Agricultural Environment and Resource，Yunnan Academy of Agricultural Sciences.
Key Words：Temperature，Diadegma semiclausum Hellén，sex ratio， eclosion percentage
Abstract：Experiments on the effect of temperature on sex ratio and eclosion characteristics of Diadegma semiclausum were conducted under two different rearing temperature conditions in the laboratory. All experiments were given conditions of 22 ℃and 25℃ at 60-70% RH with L:D//14:10 light period. Four experiments designated A, B, C and D, were carried out. In A, pupation and eclosion were done at 25℃. In B, pupation was at 25℃ while eclosion was at 22℃. In C, pupation was at 22℃ while eclosion was at 25℃. In D, both pupation and eclosion were conducted at 22℃. In treatment A, the eclosion period of female and male was 4 days, from 4th to 7th day after pupation with the eclosion peak on the 5th day. The emergence for female and male was (11.5% and 12.5%) respectively. In B, the eclosion period of female and male was 5 days, from 5th to 9th day after pupation with the eclosion peak on the 7th day, the emergence was (11.5% and 10.5%) respectively. In C, the eclosion period of female and male was 3 days, from 7th to 9th day after pupation with the eclosion peak of female on the 7th -8th day and an emergence of 9.2%, the eclosion peak time for male was on the 8th day, after pupation, with emergence was 11.4%. In D, the eclosion period of female and male was 4 days, from 9th to 12th day after pupation with the eclosion peak time on the 10th day. The emergence was 13.5% and 13.9%, respectively. The sex ratios (♀/total) in A, B, C and D were 0.41,0.39,0.82,0.76, respectively. The sex ratio of pupation at 22℃ was higher than that of 25℃ and thus showed a significant difference at 0.05 level (P<0.05). There was no observed significant difference under the same pupation temperature of 22 0C and 25℃ at 0.05 level (P>0.05) in the emergence of the insects. The sex ratios were 0.40 ± 0.07, 0.79 ± 0.05 for 25℃ and 22℃pupation temperatures respectively and a significant difference was observed at 0.05 and 0.01 level (P<0.05, P<0.01).For eclosion at 25℃ and 22℃ the sex ratios were 0.59 ± 0.11, 0.56 ± 0.07, respectively. Multiple regression analysis indicated that the linear relation equation of variables: sex ratio (Y), pupation temperature (X1) and eclosion temperature (X2) was Y=3.324 - 0.128X1 + 0.012X2(R2=0.753*, F=9.975, P<0.01). Our research results concluded that 22℃ was the optimal rearing temperature of D. semiclausum than 25 0C in the laboratory.