1·The output of some export crops, notably cashews, cotton, and pyrethrum, fell drastically.
有几种出口农作物，特别是腰果、棉花和除虫菊的产量大幅度下降。
2·The pyrethrins are mainly synthesized in pyrethrum flowers and the content is more than 95%. The content in the dried flowers is about 1.2-2.0%.
除虫菊素主要在除虫菊花中合成，其含量占整个植株的95%以上，而干花中除虫菊素含量在1.2 - 2.0%。
3·Improving the content of pyrethrins in pyrethrum through genetic engineering technology is restricted, for little is known about pyrethrins-related genes.
但国内外对于天然除虫菊素合成相关基因的研究很少，从而制约了利用基因工程技术提高除虫菊花中除虫菊素的含量。
4·To evaluate the immune toxicity of natural pyrethrum.
目的检测天然除虫菊酯的免疫毒性。
5·Pyrethrum impregnated bed nets were effective for control of malaria and it is an important measure for management of floating population.
用除虫菊酯浸泡蚊帐防治疟疾及传疟媒介获得良好效果，可作处理流动人口疟疾疫点的重要措施。