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Efficiency of the Dipper in Collecting Immature Stages of Culex tritaeniorhynchus summorosus


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Title: Efficiency of the Dipper in Collecting Immature Stages of Culex tritaeniorhynchus summorosus
Other Titles: 柄杓のコガタアカイエカ幼虫採集能率
Authors: Wada, Yoshito / Mogi, Motoyoshi
Authors (alternative): 和田, 義人 / 茂木, 幹義
Issue Date: 31-Mar-1974
Publisher: 長崎大学熱帯医学研究所 / Institute of Tropical Medicine, Nagasaki University
Citation: 熱帯医学 Tropical medicine 16(1). p35-40, 1974
Abstract: The efficiency of the dipper (15 cm diameter and 3 cm depth) in collecting immature stages of Culex tritaeniorhynchus summorosus was examined experimentally in July, 1971. In each of four water tanks (85×85 cm, water depth 10 cm) in which rice plants were growing, 100 each of first, second, third, and fourth instar larvae and pupae of tritaeniorhynchus were released, and four persons dipped the water at ten sites in each water tank by the dipper (therefore the number of dips was 160 in total); in each dip the collected larvae were counted by instar, and then returned to the same site as the dip was taken. Based on the figures obtained by the above experiment, the dipping efficiency, which was defined as the probability for one larva in 1m^2 to be collected by one dip, was established for each instar. By using this dipping efficiency it became possible to estimate the absolute density of tritaeniorhynchus larvae from the mean number per dip and the area of the rice field under study. / 20株の稲(高さ約65cm)が植えてあるコンクリート製水槽(85×85cm,水深10cm)4つの各々に,コガタアカイエカの1~4令幼虫及び蛹をそれぞれ100個体(合計500個体)ずつ放した.これらの水槽で,柄杓(直径15cm,深さ3cm)を用いてすくいとって令別個体教を記録した後,すくいとられた幼虫を水槽のもとの位置にもどした.これを各水槽において4人でそれぞれ10回ずつくり返した.このようにして4つの水槽で合計160回すくいとった結果597個体(1すくい平均3.73個体)の幼虫(蛹を含む)が得られた.最初に85×85cmの水槽に各令幼虫及び蛹併せて500個体放したので,1m^2当り500/0.85^2=692個体いた水槽からすくいとったことになる.即ち,1すくい当り平均3.73個体の幼虫が得られる時には,Im^2当りの幼虫密度は約692個体と推定される.また,1すくい当り平均1個体が得られたとすると,幼虫密度は1m^2当り692/3.73=186個体となる.この関係を用いれば,実際に水田ですくいとった柄杓当りの平均幼虫数から,1m^2当りの幼虫数を推定することができ,これに対象とした水田の面積を掛けることによって,そこに生息している幼虫の絶対数の推定値を得ることが可能となる.以上は各令幼虫及び蛹を合計した値を用いた結果であるが,各令別にも同様の計算をすることができる.
URI: http://hdl.handle.net/10069/4157
ISSN: 03855643
Type: Departmental Bulletin Paper
Appears in Collections:Volume 16, No. 1

Citable URI : http://hdl.handle.net/10069/4157

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