Influence of Different Precipitation Periods on Dendrolimus superans Occurrence:A biostatistical Analysis

Precipitation is one of the most important abiotic factors that affect Dendrolimus superans occurrence.In this study,a grey slope-correlation model was used,and a simplified grey slope-correlation model was constructed to uncover the most crucial periods of precipitation that pest occurrence.Results revealed that the two models are very similar;however,the simplified grey slope-correlation model required less calculative steps and was easier to operate.The calculation results revealed that the most crucial period occurred during the first 10 days of July(γ13 = 0.67,γ`13 = 0.69).The other precipitation periods associated with pest occurrence included the first 10 days of August(γ16 = 0.62,γ`16 = 0.61),the third 10 days of May(γ09 = 0.59,γ`09 = 0.62),the second 10 days of May(γ08 = 0.58,γ`08 = 0.60),and the third 10 days of August(γ18 = 0.58,γ`18 = 0.60).The less associated precipitation periods included the first 10 days of March(γ01 = 0.54,γ`01 = 0.47),the second 10 days of March(γ02 = 0.50,γ`02 = 0.49),the third 10 days of April(γ06 = 0.47,γ`06 = 0.48),the second 10 days of June(γ11 = 0.51,γ`11 = 0.48),and the third 10 days of June(γ12 = 0.51,γ`12 = 0.51).Precipitation in May(γ07 + γ08 + γ09 = 1.74,γ`07 + γ`08 + γ`09 = 1.79)and July(γ13 + γ14 + γ15 = 1.74,γ`13 + γ`14 + γ`15 = 1.79)was mostly associated with D.superans occurrence.The findings of this study provided a simple operative model for determining the most crucial precipitation periods of pest occurrence,and these analyticalmethods can serve as a theoretical reference for pest forecasting and early warning,which is contribute to ecological protection.