Effects of soil water content and straw substrate on reproductive performance of Whitmania pigra

ObjectiveThis experiment was conducted to determine the effects of soil water content and straw sub-strate on reproductive performance of Whitmania pigra to provide reference for scale artificial reproduction of it.MethodSexually mature parental W. pigra(2nd instar)with clitellum were cultivated in culture tanks with soil water content of 30%,40%,50%,60%,70%,and straw substrate moisture of 40%,and then survival rate of larval W. pigra,cocoon number,cocoon size,cocoon hatching rate and hatching number were observed during the experiment.ResultThe 30-day artificial breeding experiment showed significant differences in survival rate of parental W. pigra,cocoon number and cocoon rate among different soil water contents(P<0.05,the same below)but no significant difference in cocoon size(P>0.05,the same below). The maximum survival rates of parental W. pigra cocoon number and cocoon rate occurred when the soil water content was 60%,while the minimum occurred when the soil water content was 30%. According to fitted re-gression equation,cocoon hatching rate reached the maximum(95.56%)under 58.80%soil water content,and the maxi-mum hatching number was 27.59 ind under 57.61%soil water content. Survival rate of larval W. pigra,cocoon number and cocoon rate under straw substrate moisture of 40%were significantly lower than those under the same soil substrate moisture. There were no significant differences in hatching rate and hatching number of W. pigra under the two substrats. The hatching rates were both higher than 90.00%and hatching numbers were 20.67-22.00 ind.ConclusionSoil water content has significant influence on the reproductive performance of W. pigra and cocoon hatching effect,but has no sig-nificant influence on cocoon size. The experiment indicates that the optimal soil water content should be maintained at 60%.