Optimization of conditions and application effect analysis for prevention of diapause in silkworm eggs by hot water treatment

【Objective】The Box-Behnken response surface was used to optimize the treatment conditions of the hot water bath method for relieving silkworm egg diapause,and to test the hatching effect of silkworm eggs treated with wa-ter from different sources,so as to provide a scientific basis for the promotion of the hot water bath method in sericul-ture production,and to explore a safer,environmentally friendly and cost-effective method of artificial hatching for silk-worm eggs,which could be used instead of the traditional hydrochloric acid hatching method.【Method】The treatment conditions of relieving silkworm egg diapause by hot water bath were optimized by Box-Behnken response using Liang-guang No.2 as the test species,with egg age(A),treatment time(B) and treatment temperature(C) as the variables,and practical hatching rate(Y) as the response value;different sources of water such as tap water,pure water and mineral wa-ter were selected and four silkworm varieties such as Sanisi,932,Xianghui and Chun 5 were selected to test the effect of hot water bath method in relieving diapause by applying optimized conditions to silkworm eggs in hot water bath treat-ment respectively.【Result】The binomial fitting equation of silkworm egg practical hatching rate to the three variable factors was Y=91.03-2.01A-4.60B+22.89C+0.040AB+4.03AC+0.89BC-10.46A²+3.25B²-19.60C²,which was a good fit for the response surface design model.The effect of each factor on the practical hatching rate of eggs was ranked as treat-ment temperature(C)>treatment time(B)>egg age(A),in which the effects of treatment temperature were extremely significant (P<0.01),the effects of treatment time were significant (P<0.05,the same below),and the effects of egg age were insignificant (P>0.05,the same below);and the effects of the interaction between the two factors on practical hatching rate of silkworm eggs were ranked as AC>BC>AB.The optimum treatment conditions of the modified hot water bath method were:egg age 17.5 h,treatment time 13 s,and treatment temperature 50℃.The actual practical hatching rate of silkworm eggs was 97.94%,which was close to the theoretical predicted value (98.81%).The practical hatching rates of different sources of water for the hot water bath treatment of the orthogonal and inverse crosses of Liangguang No.2 were all above 95.00%,and only the practical hatching rates of Yangshan tap water and pure water1 in the hot water bath treat-ment of the orthogonal cross of Liangguang No.2 were significantly lower than those of the hydrochloric acid instant acid immersion method,but their practical hatching rate was still higher than 93.00%;there was no significant difference in the practical hatching rate of four silkworm varieties,including Sanisi,932,Xianghui and Chun 5,in the hot water bath method compared with the hydrochloric acid instant acid immersion method,indicating that the hot water bath method had a strong generalization.【Conclusion】Hot water bath method can effectively relieve the diapause of silkworm eggs,has strong generalization,and low cost,simple operation,can be used as a new method to replace traditional hydrochlo-ric acid incubation method in sericulture production.