A Study on Seasonal Prevalence of the Populations of the Mosquito Larvae and Other Aquatic Invertebrates in Rice Fields in Korea

水畓棲息 모기 幼蟲 및 其他 無脊椎動物 個體群密度에 關한 調査

The field studies on the seasonal population prevalences of the vector mosquito larvae and other aquatic invertebrates were weekly carried out in the rice fields located in front of a village of Kwangtan-samri, Byeogje-myeon, Goyang-gun, Gyeonggido throughout mosquito breeding season (June-September) in 1980, and the results are as follows. The population of C. tritaeniorhynchus larvae increased soon after heavy rainfall, and decreased to some extent during the period of the insecticide application. The seasonal prevalence of A. sinensis was rather stable, not being affected by insecticide pressure at all. The population densities of other aquatic invertebrates in rice fields were seriously suppressed by the pesticide application, and their recovery was not as same as the previous level or not at all: (1) The populations of Odonata and Ephemeroptera nymphs were drastically decreased by the first application of insecticides and never recovered through out season. (2) Coleoptera seemed very susceptible to the insecticide application, as densities were markedly decreased whenever the insecticides were applied. (3) The high density of Hemiptera shown in early June were decreased sharply after the first application of pesticides, and thereasfter, some degree of recovery was shown, but suppressed by successive each application of pesticides. (4) A native species of planaria was exceptionally not influenced by the insecticide pressure, and two peaks of the density were appeared during the heavy rainfall.

水畓棲息의 主要 모기 幼蟲과 기타 昆蟲의 個體群密度를 調査하기 위하여 京畿道 高揚郡 條里面 廣탄 3里의 一個 自然部落을 調査地域으로 選定하여 1980年 6月부터 9月末까지 週別로 채집을 實施하였다. 1. Culex tritaeniorhynchus 幼蟲 個體群密度의 계절적 변동은 다량의 降雨후에 급격한 증가 형상을 보였고 살충제 살포에 대해서 어느정도의 감소 영향을 받았다. 2. Anopheles sinensis 幼蟲의 個體群密度는 계절적으로 안정되어 있어 큰 변동을 나타내지 않았으며 강수량과 살충제 살포에 영향을 받지 않았다. 3. Odonata와 Ephemeroptera의 경우는 살충제 살포가 결정적인 억제 요인으로 작용하여 Odonata는 6월 중순의 첫 살포후에, Ephemeroptera는 7월 중순의 두 번째 살포후 각각 완전히 자취를 감추었고 그 후 個體群密度의 회복은 불가능 하였다. 4. Coleoptera의 個體群密度는 週別 변동이 심하였으며 이는 主로 살충제 살포에 의한 결과로 해석된다. 살충제 살포 前週와의 비교에 의한 감소율을 보면 Coleoptera는 69.5% (幼蟲 75%, 成蟲 58.3%)였고, Hemiptera의 경우는 75.5%였다. 5. 水畓에 棲息하는 planaria 1種의 個體群密度는 강수량에 영향을 받으며 살충제 살포에 對한 억제효과는 없는 것으로 나타났다.