Economic-Injury Level and Economic Threshold of Cephus fumipennis(Hymenoptera:Cephidae)
Limin Zhao · Xibei nongye xuebao · 2008
A total of 12 varieties of spring wheat(Triticum astivum) was tested in field-plot experiments in the Valley of Huangshui River,Qinghai Province,China,and the impacts of Cephus fumipennis Eversmann(Hymenoptera: Cephidae) on the varieties were determined.The price-related wheat loss was calculated based on the average of kernel weight reductions caused by the insect's larvae,the cost of management against the insect,and the market value of wheat grains.The economic-injury level(EIL) concept was applied to evaluate both the mean EIL of the insect in terms of larval population density and the economic threshold(ET).The results indicated that: ①the price-related wheat loss averaged 0.53 g/larva;②the mean EIL for larvae was 18.9 individuals/m2,or equivalent infestation in wheat,3.2%~6.3%;③the mean ET was 1.2 individuals/m2 for adults in summer,and 9.2 for larvae in autumn.Presented herein results may be useful in working out an IPM program of the insect.The ET may be adjustable for different varieties and applicable in different wheat production regions.