Critical examinations were directed towards the basic study of arbovirus infection of mosquitoes to provide a much sounder scientific basis. Firstly, several sets of samples of Culex tritaeniorhynchus Giles were obtained by means of simultaneous light-trap catch, hand catch and CO_2-baited trap catch, and the infection rates of Japanese encephalitis virus were compared among the samples. As the results, it was found that the infection rates were generally higher in the hand-catch samples than in the light-trap samples. Secondly, blood-engorged females of Anopheles hyrcanus complex were collected at a pig shed when Japanese encephalitis epizootic was prevalent among swine, and repeated attempts were made to verify the possibility of isolation of Japanese encephalitis virus from ingested blood rather than tissues in those mosquitoes. Ultimately, the attempts yielded two isolates of the virus which conceivably came not from the infected mosquito tissues but from the ingested blood.

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Extensive surveys were undertaken in Western Samoa during the period 1969 to 1971 on breeding habits of the confirmed and suspected vectors of subperiodic Wuchereria banorofti and of Aedes (Stegomyia) aegypti, the vector of dengue fever. Ae. (S.) aegypti breeds predominantly in artificial water containers around houses. A negligible number was found breeding in tree holes. This mosquito occurs throughout the country, even in the remote and inland areas. Ae. (S.) polynesiensis breeds in a wide range of both artificial and natural containers, but seems to prefer the latter, and is the only species breeding in crab holes. Since the above two species are often found breeding together, the single-larva-per-container survey method tends to underestimate the population of either one. Ae. (S.) upolensis is a forest mosquito, and its larvae were collected only once in a tree hole. The only species found breeding in the leaf axils of Freycinetia is Ae. (Finlaya) samoanus; and in taro (Colocasia sp.) and pineapples, Ae. (F.) oceanicus. Both species can also breed in the Pandanus axils. This plant serves the only breeding habitat for Ae. (F.) tutuilae.

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The studies were made on the mode of breeding and of hypopus formation of Lardoglyphus konoi (Sasa and Asanuma, 1951) in various kinds of diet. Two groups of diet prepared are as follows : Diet group A was based on the mixture of same weight of fish powder and yeast powder (control diet) with additional process. Some of them were added with 5% weight of soy bean oil. Diet group B was the mixture of yeast powder and one of the various kinds substances. Approximately 1,300 mites were inoculated on 20g of the diet and they were kept at 25℃ and 85% R.H. (regulated with KCl saturated solution). Number of mites in 0.5g of diet and number of mites escaped from the container were counted every week. The appearance rate of hypopus in the diet and in the escaped population were observed. The period of observations was separated into following 3 stages : 1st stage was from 1st to 3rd week, 2nd stage from 4th to 7th week, and 3rd stage from 8th to 10th week. Number of mites in Table 2 is the mean number per week in every stage. 1) The mode of breeding of L. konoi in A group diet. When soy bean oil was added in the diet at 5%, number of mites in these diets and of escaped mites rose up in the beginning of the experiment. Considering the nutritional contents of the diets may be classified in three types as follows : (1) fat abundant type; When the fat and other nutriments were contained enough in the diet, the mites counts were high even in the 1st stage and the peak of number of the mites was revealed in the 6th week and later population density of the mites decreased rapidly. This was the type that increasing speed of the mites population was high in initial period (for example, diet (1), (2), (4), (8) and (10)). (2) fat deficient type; when the fat was deficient but other nutriments were abundant in the diet, population density of the mites was low in the 1st stage. It ascended rapidly in the 2nd stage and was slowly down in the 3rd stage. This type was that the increasing speed of the mites population density was slow in the 1st stage (for example, diet (3) and (7)). (3) nutrient deficient type; when the nutriments were deficient in the diet, number of the mites was the highest in the 1st stage and decreased thereafter (for example, diet (5), (6), (11) and (12)). It was noticed that hypopus rates were higher in the nutrient deficient diets than in other diet of A group. In fish powder diet hypopus rate was the minimum in this study. 2) The mode of breeding and hypopus rate of L. konoi in the diet of B group. The maximum count of the mites was observed in the diet that whale meat extract was added to yeast powder at 5%. But in this diet, hypopus rate was low as well as in control. In the mixture of yeast powder and soy bean powder, milk casein, geratin or egg alubumin, population densities of the mites were lower than in yeast powder only. This fact may indicate that the various kinds of protein, added in yeast powder, were worse than yeast powder as a nutriment for the mites. The hypopus rate in these diets were higher than it in control diet or yeast powder. By the fact that increase of mite number was low in these diet, hypopus rate possibly increase due to deficiency of protein or unfit protein as a diet. Paticularly the mite density in soy bean powder was low, while the ratio of hypopus in that population was the highest.

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Miyatrombicula kumadai n. sp. is described from the Japanese dormouse, Glirulus japonicus, in the northern part of Honshu, Japan. The new species resembles M. tokyoensis and M. jonesae, but is distinguished from them by the different characters of palpal, scutal and body setae, and host relationships.

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Gnus fulvipes n. sp. is described based on the specimens taken from the several streams in the Oshima Peninsula, Southern Hokkaido. This new species seems to be assinged to the malyshevi group of the genus Gnus and is closely related to Gnus daisense (TAKAHASHI, 1950). However, the broad ventral plate of the male and arrangement of pupal gill filaments easily separate this species from the other included species of this group.

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In 1975 and 1976,a brief mosquito survey was carried out in Ishigakijima, the southern Ryukyus. Human- and dry ice-baited net-traps, unbaited net-trap and larval dipping were employed as collecting methods. The results were as follows : 1. Ten 5-hour nocturnal and six 2-hour daytime human-baited net catches were made during April, July and August 1976 and a total of 549 females consisting of 22 species was taken. In an urban area, Arakawa, the predominant species in the nocturnal catches were Cx. p. fatigans and Ar. subalbatus, together making up 91% of the total catch. In a mountain village, Hoshino C, Cx. p. fatigans was also predominant, forming 49% of the total catch. Ae. vexans nipponii and Cx. bitaeniorhynchus were the other common mosquitoes. In a forest area, Hoshino A and Noromizu, the species collected by nocturnal catches in considerable numbers were Ma. uniformis, Cx. bitaeniorhynchus, Cx. tritaeniorhynchus, Cx. pseudovishnui, Cq. crassipes and Ar. subalbatus. The predominant species in the daytime catches were Ae. riversi and Tr. bambusa. 2. One 5-hour nocturnal dry ice- and cowbaited net-trap catches were made at Hoshino A on April and July 1976,and a total of 113 and 950 female mosquitoes was collected respectively. The major mosquitoes were Cx. tritaeniorhynchus, Ma. uniformis, Cx. pseudovishnui, Ae. v. nipponii, Cq. crassipes, Mi. luzonensis and Cx. bitaeniorhynchus. 3. Seven 12-hour nocturnal unbaited net-trap catches were also tried at Hoshino A, on July and August. A total of 30 mosquitoes consisting of 10 species of 5 genera were found in the traps. They were small numbers of Ae. riversi, Ur. ohamai, Ur. macfarlanei, Cx. bitaeniorhynchus, Cx. tritaeniorhynchus, Cx. pseudovishnui, Cx. tuberis, Cx. fuscocephala, Cq. crassipes and Mi. elegans. 4. From April 1975 to August 1976,85 light-trap collections were made at four different areas and a total of 2,185 mosquitoes representing 20 species of 7 genera was taken. There was a marked difference between predominant mosquito species taken in the urban area, Misaki, and the forest and irrigated areas, Noromizu, Kabira and Nagura. On the urban area, 90% of the total catch was Cx. p. fatigans, while on the forest and irrigated areas, Cx. tritaeniorhynchus (29% of the total catch in the areas), Cx. pseudovishnui (29%), Ma. uniformis (10%), Ae. v. nipponii (6.0%) and Mi. luzonensis (6.0%) were predominant species.

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A new species of parasitic mite, Ewingia potamona n. sp., collected from a Japanese fresh-water crab, Potamon dehaani (White), is described and illustrated. Ewingid mites have not been found in any part of the world since Ewingiacenobitae Pearse, was described in 1929. The new species, therefore, constitutes the second member of this family.

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A number of S-alkyl O-alkyl O-aryl phosphorothiolothionates and thiolates were examined for their toxicities to mice, and organophosphorus insecticide resistant and susceptible strains of house flies. These new asymmetrical phosphorothiolothionates and thiolates having S-n-propyl showed exceptionally higher activity against both susceptible and resistant house flies than the corresponding analogues having other alkyl moieties. Usually low mammalian toxicity was demonstrated by the O-ethyl S-n-propyl O-substituted phenyl phosphoro-thiolothionates. Considering mammalian toxicity and insecticidal activity, prothiophos and its oxygen analogue are the preferred compounds as novel hygienic insecticides in the series.

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Male Culex pipiens fatigans were sterilized with thiotepa and released at a rate of 150,000-300,000 per day for five-and-a-half months into a village near Delhi around which a zone, 3km wide, was maintained free of adult C.p. fatigans production by the application of larvicides. The mosquitos for release were marked and the ratio of marked (sterile) to unmarked (wild) males was always greater than 24 : 1. In view of the known level of mating competitiveness of the sterile males a very high proportion of the matings in the village were expected to be by sterile males. Data from egg rafts collected from captured unmarked (wild) females proved that a high level of sterility was introduced into the wild population, for a period of about three weeks, but in the preceding and succeeding months the level of sterility was low. Evidence from several sources indicated that, despite the surrounding breeding-free zone, fertile inseminated females were infiltrating into the experimental village. Comparison of the density of the wild population in the experimental village with two untreated villages suggested that the period of high sterility might have caused some degree of temporary population reduction, but the evidence was not conclusive.

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The seeds of 14 species, belonging to Cruciferae family, which are commonly available in Japan, were observed for the exudation of mucilage in water and for the ability of trapping and killing Aedes albopictus larvae. The seeds of two cultured Cruciferae, Brassica campestris rapifera L. cv. Yorii-kabu in Japanese, and B. c. oleifera L. cv. Natane, as well as seeds of uncultured Cardamine scutata Thund. and Capsella bursa-pastoris (L.) were proved to produce the mucilaginous layer and to trap and kill the larvae. Thirty-two heat-killed seeds of the above four species were soaked in the water together with mosquito larvae. The percentage of larvae attached in 24 hours were 39,47,70 and 49%, respectively. The mortality of these larvae in three days were 70,60,77 and 65%, respectively. Various numbers of seeds of C. scutata were soaked together with 100 larvae for three days. It has been shown that the mortality increased as the number of seeds soaked were increased.

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Three new species of the genera Morellia R.-D. and Pyrellia R.-D., namely M. pseudonigrisquama, P. suchariti and P. ponti, are found in Thailand and described and illustrated in this paper.

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In order to maintain securely many laboratory strains of mosquitoes, a simple mosquito rearing cage "Connection cage, " in which all the required manipulations could be carried out without ever opening the cage, was designed. The connection cage (25×31×28cm) consists of 3 main parts, the upper cage for rearing of adults, the lower vessel for rearing of larvae and the connection frame connecting the upper cage and the lower vessel. In our laboratory, the cage has been successfully used for over a year in maintaining colonies of Aedes albopictus (Skuse), Aedes flavopictus Yamada, Aedes riversi Bohart and Ingram, Aedes togoi (Theobald), Aedes aureostriatus okinawanus Bohart, Culex pipiens fatigans Wiedemann, Culex infantulus Edwards and Tripteroides bambusa (Yamada).

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An epidemiological survey by questionnaire was made on arachnidism caused by the spider, Chiracanthium japonicum, in Japan. Among 42 arachnologists and 79 medical doctors, who are interested in arachnidism, 90 researchers submitted clinical records of bite cases in response to the questionnaire. A total of 28 patients of arachnidism was reported from different prefectures including Hokkaido, Aomori, Fukushima, Iwate, Miyagi, Gumma, Kanagawa, Yamanashi, Aichi, Wakayama, Mie, Nagasaki and Saga. Analysis of these 28 cases was made in which the sex of causative spiders, seasonal frequency, age and sex distribution of patients, location bitten, site of bites, severity and duration of time suffered were examined. From this epidemiological analysis, arachnidism caused by Chiracanthium japonicum was summarized as follows : A) The arachnidism occurred very commonly in Japan during a period of four months from May to August, with a peak in June. B) During the mating season the male spiders searching for mates accidentally infest human hibitats and inflict their bites most commonly during the midnight hour while the humans are sleeping. C) The site of bites was most frequently observed in the upper extremities. D) A drastic difference is observed in arachnidism caused by male versus female spiders. Male spiders produce sharp pain at the bite while the female causes intensive itching. However, both sexes produce redness over the skin lesion.

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Anisogammarus sp. collected from a mountain stream had been kept in respective conditions of different temperature from 5℃ to 20℃ over a period of 24 hours for the acclimatization. Toxicity test of Temephos was conducted at 5,10,15℃ and 20℃. In each beaker of 200ml containing 100ml of water, individuals of adult Anisogammarus sp. were placed. Temephos which was diluted with alcohol was added to become 1,5ppm and 10ppm respectively. Exposure period to the chemical was 10,30,60 minutes and 180 minutes. After respective exposure period, animals were transferred into clean water and mortality was observed 24 hours later in the rooms of the respective conditions of temperature. Three replicates were taken for each experimental condition. Toxicity of Temephos depended on the water temperature. In the case of 1ppm, the mortality of Anisogammarus sp. changed two times or more in accordance with the change of temperature from 10℃ to 20℃. Mortality of the animals also depended on the exposure period of the chemical. The relationship between the logexposure period and the mortality was linear in general in each concentration. The slope of the regression changed according to the temperature in the case of 5ppm, whereas the regression lines converged in the case of 10ppm. It was thought from the results that Anisogammarus sp. would not be damaged in the field if the concentration of Temephos was 1ppm and the exposure period was less than one hour.

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[in Japanese]

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The field tests for control of Culex pipiens pallens bred in the drainage ditches by methoprene were conducted in Neyagawa City, Osaka Prefecture. Two trials were carried out. The first trial was in June, where it was rainy season, and there was continuous water flow in the drains. When sand granule form of methoprene was applied at 1ppm to such drainage ditches, the adult emergence of C. pipiens pallens was completely inhibited for the first 5 days, thereafter, the partial inhibition (more than 50% inhibition) of adult emergence lasted for 53 days. The second trial was carried out in August. At this time, the rainy season was over, and the water in the drainage ditches was in the stational condition. The inhibitory effect of sand granule form at the same dose lasted longer, up to 72 days after treatment. Whereas, one treatment with briquet form of methoprene, when applied at 1ppm, gave virtually almost complete inhibition of adult emergence for 30 days.

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