Experimental Studies on the Role of the House Mosquito, Culex pipiens pallens in the Transmission of Bancroftian Filariasis : 4. Development and longevity in days of filariae in mosquitoes kept at a series of constant temperatures

This report deals with the results of experiments investigating the following points: (A) The development and longevity of filariae in mosquitoes exposed to a series of constant temperatures just after the feeding on the microfilarial carrier, (B) the relation between the velocity of development, or the reciprocal of developmental days to reach maturity and the rearing temperature, and (C) the maximum longevity of infective larvae in mosquitoes kept at the various constant temperatures

Experimental Studies on the Role of the House Mosquito, Culex pipiens pallens in the Transmission of Bancroftian Filariasis : 5. On the distribution of infective larvae in mosquito and the effect of parasitism of filariae upon the host insect

This is the fifth report of the theis and deals with the effect of parasitism of immature filariae on the host animal; the movement, distribution, and migrating and penetrating habits of infective larvae; the effect of parasitism of infective larvae upo

On the Familial Infection of Bancroftian Filariasis due to the House Mosquitoes

In Japan and Ryukyus where bancroftian filariasis is being transmitted respectively by Culex pipiens pallens and C. p. fatigans which are very domestic in breeding, resting, and feeding habits, the transmission of the disease is characterized by a from o

蚊によるバンクロフト糸状虫症伝搬の危険性に影響する要因について

The transmissibility of bancroftian filariasis by a vector mosquito, in other words, the epidemiological danger of filariasis infection due to the mosquito to persons in a community is very important to understand the dynamic states of the disease. It may be expressed by the product of three factors the effective microfilarial prevalence corrected considering the microfilarial density, the effective period of transmission, and the abundance of mosquitoes during the effective period. The epidemiological danger was estimated by using the data obtained in field experiments carried out from 1961 to 1967 at Nagate and Okubo Villages, Nagasaki Prefecture, Japan, under the changing conditions in microfilarial prevalence and density due to the control of vector mosquitoes or the treatment of positive persons by drugs.ある部落におけるバンクロフト糸状虫症の蚊による伝搬性,即ち人間に対するフィラリア症感染の疫学的危険性は本病の動的様相を理解する上で極めて重要である.これは次の3つの要因の積として表わし得る:(1)仔虫数によって修正した有効仔虫保有率,(2)有効伝搬期間,(3)有効伝搬期間中の蚊の多少.これら3つの要因について,伝搬蚊の駆除あるいは患者に対する投薬によって仔虫保有率が変化しつつある長手及び大久保部落で得られた値を用い,疫学的危険性を吟味した

日本脳炎伝搬蚊,特にコガタアカイエカの生態 : 4.コガタアカイエカの未成熟期の発育と特に春と秋における温度との関係

Eggs of Culex tritaeniorhynchus summorosus laid by wild-caught and laboratorycolonized females were reared to adults under outdoor natural conditions particularly in spring and autumn, and the relation of the developmental period of immature stages of the mosquito to the extrinsic temperature was given. The results indicated that the developmental speed of immature stages given as the reciprocal of period decreases clearly with the drop of temperature and the development hardly occurs at the temperature below about 16℃.野外で採集した,または実験室で累代飼育中のコガタアカイエカ雌成虫が産んだ卵を,屋外飼育室の自然条件下で特に春及び秋に成虫にでま飼育して,温度と未成熟期の発育期間との関係を求めた.その結果,発育日数の逆数として求めた発育速度は,温度の低下と共に顕著におそくなり,約16℃以下では殆んど発育しないことがわかった

種々の量の血液を摂取したコガタアカイエカの濾胞の発育及びその後の吸血,産卵活動

The follicular development of Culex tritaeniorhynchus summorosus females after taking various amounts of blood was observed, and the following facts were demonstrated. Even in the females which have taken merely a trace amount of blood insufficient for filling up the midgut, many follicles do initiate the development, but none of them mature. When the uptake amount of blood increases, some follicles develope to mature eggs, and generally the more amount of blood is taken, the more mature eggs are produced; those follicles which have initiated the development but have failed to mature are degenerated. The females which have smaller number of mature eggs than the normal will lay a small egg raft or will take a second blood meal, depending on which is given the oviposition place or the blood source.種々の量の血液を摂取したコガタアカイエカ雌成虫の濾胞の発育について調べた結果次の点が明らかとなった.中腸を満たすに足りないほど少量しか吸血しなかった雌でも,多くの濾胞が発育を始めるが,成熟卵にまで発育する濾胞はない。吸血量が増えると成熟卵まで発育する濾胞が出現し,その数は.吸血量が増えるほど多くなる.その場合に,成熟卵にならない濾胞は発育途中から退化する.少数の卵しか持たない雌は,産卵場所を与えると,きわめて小さな卵塊を産卵するが,産卵場所を与えずに吸血源のみを与えると抱卵したまま再吸血する

日本に於けるバンクロフト糸状虫症の伝搬蚊に対する駆除作業の効果

The most important vector of bancroftian filariasis in Japan is C. p. pallens and the secondary but only a little important one is Ae. togoi. Against the former species larvicide application once a week is practicable and very effective, but against the latter it is difficult. Residual spray by organophosphorous imagicide is very effective for the adults of both species, reducing almost perfectly the population density for a month and suppressing the transmission of the disease for about two months. Experimental eradication of filariasis by only vector control has been carried out in a village since 1962 under the cooperation of villagers in practice of timely applications of larvicide and imagicide. The success seems probably achievable by about the end of 1969.日本での最も重要なバンクロフト糸状虫症の伝搬蚊はアカイエカで,あまり重要ではないが第二番目の伝搬蚊はトウゴウヤブカである.前者に対しては週1回の幼虫駆除が実行可能であり極めて有効である.然し,後者に対しては幼虫駆除は困難である.成虫に対する有機燐剤による残留噴霧は両種の伝搬蚊に対して極めて有効であって的1ケ月間は成虫の生息密度を殆んど完全に抑圧し,約2ケ月間は蚊による感染を防止し得る.伝搬蚊を駆除する事のみによる糸状虫症の撲滅を計画し1962年以来某部落で,村民の協力を得て,幼虫駆除及び残留噴霧を適正に実施しているが,1969年の末頃迄にはその撲滅は可能であると思われる

日本脳炎ウイルスの生態学的研究.1968年の調査成績

A serial survey on the ecology of Japanese encephalitis (JE) virus was made in 1968. Virus isolation was negative from 848 hibernated females of Culex tritaeniorhynchus collected in March to early May. In mid May, when newly emerged females appeared, and thereafter, attempts to isolate the virus were continued, but it was July 23 that the first isolation was made. A strain of JE virus was isolated each from C. pseudovishnui in early August and from Aedes vexans nipponii in late July. Eight other species of mosquitoes were negative for JE virus throughout the year. The pigs susceptible to JE virus were exposed in nature to mosquitoes including hibernated females of C. tritaeniorhynchus in spring without detecting the rise in hemagglutination inhibition (HI) antibody in their sera. Continuing the exposure to mosquitoes, the HI antibody was detected only after early August. The number of human cases was smaller than in any of the previous three years. One of the reasons is considered to be that the number of vector mosquitoes was smaller at the time of the epizootic in pigs.前年までに引き続き,1968年に日本脳炎ウイルスの生態学的調査を行なった.3月-5月上旬に採集したコガタアカイエカ越冬雌成虫848個体からはウイルスは分離されなかった.新生雌成虫が出現し始めた5月中旬及びそれ以後も分離を試みたが,始めて日本脳炎ウイルスが分離できたのは7月23日であった.シロハシイエカからは8月上旬に,キンイロヤプカからは7月下旬に,各々1株の日本脳炎ウイルスが分離された.感受性の豚を各々1頭ずつ2月下旬に3部落の豚舎に配って,自然に蚊から吸血されるままにして飼育し続けて,HI抗体が出現する時期を調べたが,抗体が検出されたのは8月上旬以降であった.発生患者数は,過去3年の何れにおけるよりも少なかった.その理由の1つは,豚で日本脳炎の流行が起っている時期のコガタアカイエカの数が少なかったことであると考えられる

日本脳炎伝搬蚊、特にコガタアカイエカの生態 : 2.終夜採集法による夜間吸血活動性と吸血嗜好性

All-night-catches of mosquitoes were made four times at human huts, by human-baited-traps, at animal sheds, and by dry-ice-traps, two times in June and once in September, 1965 and once in August, 1966. The hourly distributions of the collected females of Culex tritaeniorhynchus usually had a high post-sunset peak, and occasionally a low peak before or around sunrise. It was also shown that the order of mosquito species in the appearance of the post-sunset peak, early to late, is as follows: Aedes vexans nipponii, and Armigeres subalbatus>Anopheles sinensis, Culex neovishnui, and C. tritaeniorhynchus>C. pipiens pallens. As for the host preference of mosquitoes, it was shown from the percentage compositions of mosquitoes collected by various methods that C. tritaeniorhynchus, An. sinensis, Ae. vexans nipponii, and Ar. subalbatus are zoophilic; C, neovishnui is ornithophilic and zoophilic; and C. pipiens pallens is ornithophilic and anthropophilic.1965年6月と9月及び1966年8月に,人またはドライアイスを用いたトラップにより,あるいは豚舎,牛舎または鶏舎において,計4回の蚊の終夜採集を行なった.コガタアカイエカ雌成虫の採集数の時刻的消長には,多くの場合には日没後にピークが見られ,ある場合には日出前後にも小さなピークが見られる.日没後のピーク出現の時刻は蚊の種類により違っていて,次の順序である:キンイロヤブカ,オオクロヤブカ>シナハマダラカ,シロハシイエカ,コガタアカイエカ>アカイエカ.種々の方法で採集した蚊の種類構成から,吸血嗜好性を判断すれば,次の通りである:コガタアカイエカ,シナハマダラカ,キンイロヤブカ,オオクロヤブカは大動物嗜好性;シロハシイエカは鳥類嗜好性及び大動物嗜好性;アカイエカは鳥類嗜好性及び人類嗜好性

日本脳炎伝搬蚊,特にコガタアカイエカの生態5.コガタアカイエカとシナハマダラカの越冬

The time of awakening from winter diapause in Culex tritaeniorhynchus summorosus and Anopheles sinensis was examined from the data of mosquito catches in winter and early spring from 1965 to 1971 in the Nagasaki area. The results indicated that at least until the end of February most females of G. t. summorosus are still in a diapausing state, i. e., they do not feed on animals even on a warm day, while many of An. sinensis females are in such a physiological state already in January that they can feed on animals if the temperature is high enough for their flight activity. From the observations in the field and the experiments in the laboratory, it was implied that the main overwintering place of C. t. summorosus, and probably An. sinensis too, is the underground small space of stone walls, banks and the likes which are common in the terraced rice field area.コガタアカイエカとシナハマダラカの雌成虫が冬期の休眠から覚醒する時期を,長崎地方で1965-1971年の冬及び早春に採集した蚊の資料を用いて吟味して,次の結果を得た.コガタアカイエカの大多数の雌成虫は少なくとも2月の末までは休眠状態にあり,暖い日であっても吸血に来ることは殆んどない.これに反してシナハマダラカの雌成虫の多くは1月には既に休眠から覚醒していて,気温が飛翔活動に充分なほど高くさえあれば,多数の吸血蚊が観察される.野外及び実験室での観察から,コガタアカイエカが(そしておそらくシナハマダラカも)越冬するのは,階段状の水田が多くある地方の石垣や土手などの中の小さなすき間であるように思われる