一、农作物害虫的严重性据西德的调查资料,全世界每年由于病害、虫害以及杂草所造成的农作物产量损失,平均约为30％,折合约为1,230亿美元。就地区而论,以亚洲损失最大,损失率为43％,非洲42％,南美33％,欧洲25％,因运输和保管损失15％。按各种作物来分,以水稻损失最大,损失率为46％,玉米34％,棉花34％,马铃薯32％,蔬菜28％,小麦24％。据全国植保工作会议资料,1973年我国11个省统计防治病虫害结果,即挽回粮食达120多亿斤,占11省粮食总产4％;挽回棉花300多万担,占总产的10％。 I. Severity of Crop Pests According to the survey data from West Germany, the annual crop losses due to diseases, pests and weeds in the world are about 30% on average, equivalent to about 123 billion U.S. dollars. In terms of the region, the loss is the largest in Asia, with a loss rate of 43%, 42% in Africa, 33% in South America, 25% in Europe and 15% in transport and custody. According to a variety of crops to rice loss the most, the loss rate of 46%, 34% of corn, cotton 34%, 32% of potatoes, 28% of vegetables, 24% of wheat. According to the information of the National Plant Protection Conference, in 1973, the statistics of pest and disease control in 11 provinces in China showed that over 120 billion jin of grain were recovered, accounting for 4% of the total grain output of 11 provinces. More than 3 million tons of cotton were recovered, accounting for 10% of the total output.