Occurrence and Damage Regularity of Spodoptera litura in Broccoli

摘要

[Objective] The paper was to explore the occurrence and damage regularity of Spodoptera litura in broccoli,and to reveal the annual movement regularity and seasonal fluctuation regularity of S.litura population.[Method] The monitoring data of sexual attractants at fixed points for 11 consecutive years were summarized and analyzed.[Result] The large occurrence frequency of S.litura in Taizhou was 36.4%;the annual movement showed a downward-opening parabolic form,and the movement trajectory was N =-18.416 t^(2)+182.51 t +179.71,t ={1,2,3,…,n}(n =11;r =0.691 7*).The seasonal fluctuation showed a trend of peak oscillation attenuation curve,and the total moth quantity gradually decreased from sowing to heading stage.The functional model of average daily quantity was m=0.000 2 d^(2)-0.067 5 d+6.797 3,d={1,2,3,…,n}(n =186,r=0.955 2**).Air temperature was the main external factor affecting the seasonal variation of quantity,and there was a significant correlation be-tween the number of ten-day moth trapping quantity and ten-day average temperature:M =0.243 T^(2)-6.935 1 T +46.681(n =108,r =0.560 2**)or M=2.734 4 T-35.446(n=108,r=0.500 3**).Therefore,the moth quantity in the field increased with the increase of ten-day average temperature,and the period from July to September with high temperature and less rainfall was the peak occurrence period of S.litura.[Conclusion] These models can be used to improve the prediction and early warning levels of S.litura in broccoli,and has good guiding significance for decision-making and prevention.