Pan Jia-Yun, Zheng Xiang, Qian Hui-Lin, Liu Chao-Fan, Guo Chuan-Kun, Jiang Miao-Gen, Chen Huan-Lu, Gu Zheng-Cheng
National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Center of Malaria, Schistosomiasis and Filariasis, Shanghai 200025, China.
Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi. 2012 Jun 30;30(3):218-23.
To investigate the impact of the application of chemical pesticides on the distribution of Anopheles anthropophagus in rice fields and the malaria incidence.
Twenty-four villages from 16 counties in the provinces of Zhejiang, Sichuan and Guangxi were chosen for the surveys in the period of 1983-1987. For the survey of An. anthropophagus, indoor human bait trapping until midnight and catching the mosquitoes in all the nets in early morning were carried out to get the density and population ratio of the mosquitoes. Historical data on Anopheles spp., malaria incidence, acreage of the single or double season cropping of rice and on the quantity of chemical pesticide used in rice fields were collected from the study areas.
In Hang-jia-hu region of Zhejiang Province, double season rice cropping was performed at that time, the quantity of pesticides used in 1973 was 45 kg/hm2, which was as high as 50 times than that in the 1950s. The density of An. anthropophagus decreased yearly, no An. anthropophagus could be found at 11 survey points in late 1980s. The malaria incidence dropped to less than 1 per 10000. In Leshan and Yibin areas of Sichuan Province, the major cultivation was single cropping, pesticides were applied in paddy fields since 1960s, and the average quantity of pesticides used was 8.6 kg/hm2 during 1970s-1980s. No significant difference on the density of An. anthropophagus was revealed between 1980s (86.2%) and 1960s (82.2%) (chi2=0.63, P>0.05). After mid-1980s, pesticide use gradually increased, and reached to 18.18 kg/hm2 in average in the years after 2000. The density of An. anthropophagus decreased, no An. anthropophagus was found in 2010 in the area surveyed and no malaria cases were reported as well. With double season cropping in Huanjiang County of Guangxi, the pesticide amount consumed was 1.79kg/hm2, 25.13 kg/hm2 and 7.68 kg/hm2 in paddy fields in 1960s, 1970s, and 1980s, respectively. The proportion of An. anthropophagus in anophelines was 52%(1 747/3 392) in the beginning of the 1980s. After the year 2000, the average pesticide use increased to 20.38 kg/hm2 in paddy fields. It was difficult to find An. anthropophagus in human dwellings after 2008. The average annual malaria incidence dropped to 0.14 per 10 000.
Change of farming activities and especially use of chemical pesticides in high quantity at the rice fields undermine the breeding environments of An. anthropophagus, greatly reduce the mosquito population and therefore the malaria incidence.
探讨化学农药的施用对稻田嗜人按蚊分布及疟疾发病率的影响。
1983 - 1987年期间，选取浙江、四川和广西三省16个县的24个村庄进行调查。针对嗜人按蚊的调查，采用室内通宵人饵诱捕法，并于清晨收集所有蚊帐内捕获的蚊虫，以获取蚊虫密度及种群比例。收集研究区域内按蚊种类、疟疾发病率、单季或双季水稻种植面积以及稻田化学农药使用量的历史数据。
浙江省杭嘉湖地区当时种植双季稻，1973年农药使用量为45千克/公顷，是20世纪50年代的50倍之多。嗜人按蚊密度逐年下降，20世纪80年代末11个调查点未发现嗜人按蚊。疟疾发病率降至万分之一以下。四川省乐山和宜宾地区主要种植单季稻，自20世纪60年代起在稻田施用农药，20世纪70 - 80年代农药平均使用量为8.6千克/公顷。20世纪80年代（86.2%）与20世纪60年代（82.2%）嗜人按蚊密度无显著差异（χ2 = 0.63，P > 0.05）。20世纪80年代中期后，农药使用量逐渐增加，2000年后平均达到18.
