The relationships between physico-chemical characters of water in rice fields and their suitability for breeding of the mosquito larvae, Anopheles sinensis were studied during the summer in 1974. The census fields (B-G) were located in the suburb of Urawa city 20km north of Tokyo. Census fields ranged 0.5-3.0 are containing about 1,600 hills of rice plants per are. The water sample was taken with the use of the quadrat device (25×25cm) which was pushed firmly into the bottom mud in rice field (Ikemoto, 1976). Temperature, quantity, pH, and concentration of DO and NH_4-N of the water sampled were determined with the instruments or by the chemical analysis. The collected immature mosquitoes were classified into larvae of successive instars and pupae. It was shown that there is a positive correlation between the number of larvae (pupae inclusive) and the concentration of NH_4-N in the water sampled within the field at the same time. Moreover, the relation of the mean number of immature mosquitoes and the mean concentration of NH_4-N in each field during the summer was shown to be positive in correlation, at least, within the range from 0.1 to 0.4ppm of concentration. However, the relations between the larval density and the other characters of the water were not clear. Some discussions were given on the relation between the spatial distribution patterns of immature stages of this mosquito (Ikemoto, 1978) and the heterogeneity of the habitat water conditions presented in this paper. Further studies are needed to prove the propriety of the assumption that the NH_4-N concentrations within a field or among the fields have some positive relations with the oviposition preference of adults, the abundance of immature stages and their survival rates.

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Experiments and analysis were made about the evaluation method of insecticidal efficacies against the German cockroach in the field. The data discussed in the present study were obtained by spraying a mixed emulsifiable concentrate (EC) of fenitrothion (5%) with phthalthrin (0.5%) and iodofenphos (10% EC) at ten stations comprising restaurants, snacks, and bars ih Nagoya City, Japan, infested with the German cockroach, Blattella germanica (L.). The reduction rate is given by the following formula; y=(x-z)/x×100 (1) where, y is the reduction rate, and x and z are the means of cockroaches trapped before and after treatment, respectively. It is considered that the mean of cockroaches decreased (numerator of the formula) varies depending on the mean of cockroaches trapped before treatment. The relation between them will be given by the following formula; D=mx+n (2) where, D is the mean of cockroaches decreased, and m and n are the regression coefficients; 0≦m≦1,n≦0. Substitution of (2) into (1) gives y=(m+n/x)×100 (3) Thus, the reduction rate can be shown by these parameters and the mean of cockroaches trapped before treatment. As the equation (3) is a fractional function of x, m represents asymptote parallel to x-axis as well as the limit of the reduction rate. Replacing 1/x in the equation (3) with X, it can be rewritten as follows; y=(m+nX)×100 (4) This indicates that the reduction rate can be shown by a linear equation. From the above equations, it can be expected that the reduction rate takes the high value when both m and x are large enough and n is relatively smaller. Since confidence intervals of both m and n can be calculated by regression analysis, insecticidal efficacies can be evaluated by these values. When the above method is introduced into the analysis of data in the present study, no significant difference in the reduction rates was shown between the two insecticides sprayed.

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Four new chiggers from bats in the northern part of Honshu, Japan were described; i.e., two external parasites, Ascoschoengastia narai n. sp. and A. mukoyamai n. sp. off Vespertilio orientalis and Nyctalus lasiopterus aviator; two intranasal species, Microtrombicula vespertilionis n. sp. and M. tenmai n. sp. off V. orientalis. Of the above, the genus Ascoschoengastia was newly found from the Japanese bats.

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In 1931 Shiraki described a new cockroach species "Phyllodromia kumamotonis" from Kumamoto, Kyushu, based on a single female specimen. Later Shiraki gave a brief description of it in Japanese (1950), but nothing has been added to the real taxonomic status of this insect. Recently this was listed in Princis' world Catalogue (1969) as belonging to the genus Margattea. Since 1952 I have accumulated my own material from South Japan, i.e., Kyushu and its annexed islands, Tsushima, Tanegashima, and from the area along the Pacific coast of Honshu up to Chiba Prefecture. From the islands of Amami, Okinawa, Yayeyama and Taiwan we found a rather pale coloured Margattea allied to kumamotonis. The other three cockroach forms were also added including one Taiwanese species. In 1973 I had an opportunity to check the type specimens of Taiwanese "Theganopteryx perspicillaris Karny" preserved in the Institut fur Pflanzenschutzforschung at Eberswalde, D. D. R. and foundthat it is one of the cockroaches now we are considering. This year (1978) Kumar and Princis established a new genus Theganosilpha recognizing "Theganopteryx perspicillaris" as type-species and emphasized the presense of serration on the tarsal claws as a generic character. From this procedure it became clear that the Taiwanese large-sized insect is Theganosilpha perspicillaris and the other two from South Japan are new Theganosilpha species closely allied to the first species.

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Seven species of the genus Spinturnix von Heyden, 1829 (Spinturnicidae), including a new species, were recorded from Japan with collection records. Spinturnix myoti (Kolenati, 1856) (sens Rudnick, 1960) was regarded as a species complex. The new species was Spinturnix maedai n. sp. parasitic on Murina leucogaster hilgendorfi and Murina aurata ussuriensis.

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A limited field trial was undertaken in Labuan Island Sabah to determine if larvicidal treatment of open containers of stored water could achieve effective control of Aedes aegypti, a vector of dengue fever and dengue haemorrhagic fever. The insecticide used was abate 1% sand granules and the method of evaluation was the single-larva-per-container method. The lethal effect on Ae. aegypti of each application of abate at a concentration of 1ppm lasted 3 to 3.5 months and was clearly reflected in the resurgence and reinfestation of the species. A higher proportion of the larvae collected from indoor containers were Ae. aegypti. Ae. albopictus larvae in outdoor water collections tended to increase markedly during the trial. The mean Breteau index of aegypti was reduced from 83.6 before larviciding to 24.7 four months after. The final Breteau index after 11 months was 10.5 and the mean premise index fell from 52.9% to 7.6%. Ae. aegypti comprized 64.8% of the larval collections, Ae. albopictus 28.3% and other species, principally Culex pipiens fatigans 6.9%. The single-larva-per-container technique provided a useful quantitative measure of the larval densities in the treated areas.

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Two new genera, Hosarcophaga and Kanomyia are established, and the following 10 new species of sarcophagid flies : Kanomyia bangkokensis, Parasarcophaga spinipenis, P. amplicercus, Sarcosolomonia aureomarginata, S. trifulcata, Phallosphaera kurahashii, Sarcorohdendorfia multivillosa, S. montana, Pierretia melania and Blaesoxipha thailandica are described from Thailand. Male genitalia are illustrated.

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Mesomermis japonicus n. sp. is described from larvae of Simulium japonicum collected in the Yataro River of the Kanagawa Prefecture in Japan. It can be distinguished from previously described Mesomermis species by the shape and size of the amphids and the character of the spicules and vagina. At 15℃, the postparasitic juveniles molted between 9 and 23 days after emergence, began ovipositing 6-23 days later and hatching occurred 34-41 days after oviposition. Females produced between 556 and 2936 eggs during their life time.

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To study the mode of utilization of a space in Periplaneta fuliginosa (S) sooted papers were set on the floor, wall and shelves in a bare room and the frequency of tracking by them was observed ('the tracking method'). Catching by butter traps was carried out in the same study and the following results were obtained. 1. The sooted papers set on the wall side of the floor were clearly clawed off, and the frequency of track printing showed evidently higher degree with a width of about 5cm along the wall side on the papers than the rest part of those. This fact indicates that the cockroach has tendency apt to crawl along vertical phase (ex. the wall). On the contrary, papers set at the central zone of the room were not clawed off so frequently and track was layed in various directions. It seems, therefore, that the cockroach did not move to central zone so frequently in such bare room. 2. The papers set on a wall had tracks along lintels and skirting board. The highest degree of tracking frequency could be observed on the papers set on the top board of shelves. 3. From these characteristic tracking results it was ascertained that the cockroaches mainly moved along the third dimension in the three dimentional phase in their habitat at where they could move freely. 4. A correlative concept was able to designed from the results obtained by butter trapping and tracking method whenever comparison was done with the same point in the field. It seems, therefore, that the butter trapping would roughly inform the mode of utilization of a space in this species as well as other information (s) if fairly many traps were employed. Besides, the tracking method using sooted paper seemed to be convenient for population census when density of the insect was seemed not so high.

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Ten species of horseflies, totally 2,000 individuals, were collected at 7 station in Toyama, Iwate or Aomori Prefecture, either by dry-ice trap or by sweeping. Their nectar-sucking behaviors were discussed after microscopic as well as chemical examinations on nectars ingested. 1. The overall nectar sucking rate in total individuals was 82%, among which, part of the large-sized horseflies, such as Tabanus chrysurus and T. katoi showing rather lower rate. The distribution of nectar-sucking degree was, fully-sucked 10%, and medium and few 36% each. 2. The largest quantity of nectars sucked was 41μl in T. chrysurus, 35μl in T. katoi, 20μl in T. rufidens and T. trigeminus, 14μl T. humilis and T. sapporoensis, and 13μl in T. iyoensis. 3. The sugar concentration of nectars sucked ranged from 16.6% to 77.5% and there seemed to exist a tendency that the smaller the size of the species, the higher the sugar concentration. 4. The distribution of nectars after ingestion was, in general, limited only in the diverticulum, while, in 24% of T. iyoensis, in 10% of T. sapporoensis and in 6% of T. rufidens, nectars were found also in the midgut. 5. Paper chromatographic analysis of nectars indicated that 88% of the individuals possessed fructose, glucose, sucrose and maltose, and 63% of then additionally possessed raffinose and/or melibiose. 6. Judging from the appearance rate of fully nectar-sucked individuals among those coming for blood sucking, the diurnal activity of nectar-sucking in T. iyoensis, T. sapporoensis, T. humilis and T. rufidens seemed to be parallel to the blood-sucking activity. 7. Comparison of nectar-sucking between the autogenic T. iyoensis and strongly blood-sucking (anautogenic) T. chrysurus revealed that there was little difference in the rate and degree of nectar-sucking as well as the composition and concentration of sugars. A significant difference was observed only in the distribution of nectars after ingestion, that is, in T. iyoensis nectars were detected also in the midgut. This seemed to be a distinctive character of the autogenic species, since the same distribution pattern was observed also in T. sapporoensis and T. rufidens, which belong to the same autogenic species group.

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Niclosamide (5,2'-dichloro-4-nitro-salicylicamide), B-2 (Sodium 2,5-dichloro-4-bromophenol) and Yurimin (3,5-dibromo-4-hydroxy-4'-nitroazobenzene) were tested for their toxicity against fish using juveniles of the guppy. The juveniles provided for this test were those of a yellow strain selected at National Institute for Environmental Studies, Tsukuba, Japan. The juveniles had been seperated into two groups soon after parturition, one with food and another without food and they had been kept until 18th day when high mortality occurred among the preserved population without food. Among the three chemicals tested, Yurimin and Niclosamide had high toxicity to the juveniles and B-2 was slightly lower in its toxicity. In the case of B-2,LC_<50> values between the batch with food and that without food did not differ till 2 days after parturition but thereafter differentiated with age. Namely, the batch with food increased gradually the tolerance against the chemical, whereas the starved batch did not change the susceptibility up to 10 days after parturition. On the contrary, the LC_<50> value decreased lineally with the age of juveniles, when Niclosamide was tested. The results would suggest the usefulness of the juveniles of the guppy as a standard fish in testing the toxicity of chemicals.

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The influence of temperature on the development of two housefly populations, organophosphorus insecticide-resistant Hokko colony and susceptible Takatsuki strain, was studied in the present experiments, using two kinds of culture medium with different initial water content (approximately 33 and 50% respectively). Two hundreds larvae were reared in one container receiving 150g of medium, and two or three containers were used in each experiment. The viability of Hokko colony was more than 90% at 20°-35℃ and a little lower at 15℃, but its mortality was very high at 40℃. Takatsuki strain showed the same tendency as Hokko colony except that viability was approximately 60% at 35℃ (Takatsuki was not reared at 15℃). The relation between mean medium temperature (t) and rate of development (ν) in Hokko colony could be expressed in, ν=0.0082t-0.0810,for egg-larval period, ν=0.0120t-0.1376,for pupal period, and ν=0.0049t-0.0522,for egg-pupal period. And Takatsuki strain showed the same tendency at 20°-35℃. The developmental zeros and thermal constants calculated from these equations were 9.9℃ and 122 day-degrees in egg-larval stage, 11.5℃ and 83 day-degrees in pupal stage, and 10.7℃ and 203 day-degrees in egg-pupal stage, respectively. The results in egg-pupal stage were compared with those obtained by other investigators and found to be suitable to them at temperatures below 30℃. The body weight of pupae was lighter when larvae were reared at higher temperature or in culture medium of lower initial water content. And pupae of Hokko colony were heavier than those of Takatsuki strain at 35℃. By comparing the present results to those of others, it is considered that the suitable temperature range for development of the housefly lies between 17°-35℃, and developmental zero and critical high temperature are approximately 10° and 40℃, respectively. The reason for lightening effect of lower initial water content on the body weight of pupae is considered that available food quantity was smaller at lower water content, where the greater part of medium was dried more quickly. In comparison between two populations, there were no distinct differences in duration of development. It may be, however, concluded that, Takatsuki strain, at least the present sub-strain, in immature stage is inferior in the adaptability to higher temperature of 35℃, for it shows lower viability and the body weight of its pupae is lighter than Hokko colony.

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A survey of the habitats of Aedes albopictus and Ae. riversi was carried out in selected locations in the southwestern part of Japan during the summer seasons of 1975 and 1976. It was observed that Ae. albopictus attacked human bait predominantly in open areas near densely populated regions while Ae. riversi preferred mostly at sparsely populated forested areas for feeding. The larvae of both species were found equally in both artifical breeding containers such as discarded cans and natural breeding containers such as tree holes, bamboo stumps. Therefore, differences of the habitat of each species seemed to be due to their flight places whether in open areas or in forested areas.

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A chironomid species breeding commonly in sewage ditches and urban streams in Japan had been called until recently by a Japanese name of 'sesuji-yusurika' or by a scientific name of Chironomus dorsalis Meigen, but was recently shown to be a new species, Chironomus yoshimatsui Martin and Sublette, 1972. In the present study commenced by the author and his colleagues in 1976,collections of all stages of chironomids in the fields as well as their laboratory rearings have been conducted, for taxonomic and biological investigations of this little known insect group. Among several species of the flaviplumus group found breeding in pools in Tsukuba and Tokyo, a species almost identical in the structure of male hypopygium and coloration to Chironomus dorsalis of Strenzke (1959) was named by Sasa (1978) as a new species, Chironomus strenzkei. However, it was eventually shown that this tribial name was preoccupied by another Amazonian species by Fittkau (1968), and thus a new name, Chironomus nippodorsalis, is proposed to replace C. strenzkei of Sasa (1978).

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[in Japanese]

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[in Japanese]

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The susceptibility of five common species of mosquitoes in Japan to the infective stage of mermithid nematode Romanomermis culicivorax was examined. The incidence of parasitism was highest in Culex pipiens molestus, followed by Cx. p. pallens, Aedes albopictus, Ae. togoi, Armigeres subalbatus. Effect of type of nematode introduction and host arrangement was studied. 2400 nematodes in infective stage were released in a 6.5×120cm stagnant water path, comparing two types of introduction. In the 1st type nematodes mixed well in overall water and in the 2nd type nematodes were introduced at an end of the path. Eight screened containers 30 larvae of Cx. p. molestus each were variously located. Parasitism was highest when nematodes were mixed in overall water and the larvae were held in 8 locations. No parasites were recovered when nematodes were introduced at an end and the larvae located 120cm away. When nematodes introduced at an end and the larvae were placed every 15cm from the point of introduction, the parasitism was highest at the nearest place from the released spot. Number of parasites recovered (N) is given as N=-48.4 log D+96,where D is distance from the released point. These findings indicate that the nematodes in infective stage may not disperse more than 100cm in stagnant water.

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The emergence time of two black-flies, Simulium (Simulium) arakawae and S. (Gnus) bidentatum, were observed in the laboratory by rearing field-caught pupae in Kagoshima, Japan. Under natural condition, most flies of both species were found to emerge during the daylight period with the peak of emergence between 6 : 00 and 12 : 00. There was no sexual difference in emergence time. When pupae were set under continuous light or reversed light-dark cycle conditions, they emerged during the period corresponding to daylight period of normal condition. These results indicate that the emergence pattern is probably controled by the rhythm which was established by the light-dark cycle during larval stage.

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