An experiment was carried out to observe the effects of temperature and humidity on the reproduction of the mite Dermatophagoides farinae on a culture medium composed of the mixture of the equal amount of dried yeast and fish meal. Approximately 900 mites were inoculated into each of 16 glass container (50ml beaker) containing 25g of the mite food, and were preserved separately in dessicators regulated at different levels of relative humidity by the use of saturated solution of 4 kinds of salts (75-77% with NaCl, 60-68% with NH_4NO_3,55-58% with NaHSO_4,and 39-41% with K_2CO_3). The containers were further kept in incubators regulated at the temperatures of 20℃, 25℃, 30℃, and 35℃, each 4 dessicators with different humidity levels in the same incubator. The population density of the mite was measured at weekly intervals by counting the number of mites recovered with the saturated saline floatation method from 0.5g of the culture media. As shown in Table 3 almost no growth of the mite population was observed in media kept at 20℃ and 35℃, while more or less remarkable reproduction was seen at the temperature of 25℃ and 30℃ so far as the relative humidity was adequate, i. e. at 60% or 57-58%. In general, the speed of reproduction was faster at 30℃ than at 25℃, but higher population density was reached at 25℃ than at 30℃ in relation to the elapse of time. The maximum mite count observed at 25℃ and 57% RH was 4,800 after 23 weeks, that at 25℃ and 60% RH was 4,460 after 13 weeks and 5,665 after 23 weeks, that at 30℃ and 60% RH was 2,445 after 11 weeks. Almost no increase in the population density was observed at the relative humidity of 75-77%. In general, it has been observed that the reproduction of Dermatophagoides farinae in the culture media is considered to be slower but persists longer than that of Tyrophagus putrescentiae, and that the former is adapted to breed at lower relative humidity than the latter.

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The author has previously discussed the method of sampling Culex pipiens fatigans in houses by hand collection with some aspects of resting behaviour of the mosquitoes in Ceylon (Kurihara, 1970). Following the previous report, the pattern of spatial distribution of the resting adults in daytime was analysed statistically. The data examined were of mosquito collections at nine sections or house groups, 60 houses per section, in Peliyagoda town, and 10 sections, 45 houses each, in Kelaniya town. As a result, the mean value of numbers collected per house in each section is always less than the variance. The frequency distribution of the mosquitoes is not random but over dispersion (Fig. 1). It fits well with the theoretical distribution of the negative binomial. According to the Bliss & Owen's (1958) method, a common k of the negative binomial distribution for all the section samples was calculated in the two towns respectively. Then the relationship between the mean number of mosquitoes per house (x^^^-) and the per cent of mosquito-free houses (P_0) was studied. Observed values were plotted on a graph (Fig. 3) following the formula P_0=(1+x^^^-/k)^<-k>. It is found that the mean number of mosquito of the towns can be estimated from the per cent of mosquito free houses.

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A joint study was conducted for a period over one year on the ecology of the guppy, Lebistes reticulatus Peters, which was discovered in the autumn of 1970 to be breeding in highly polluted water of Yoshikawa River running through the heart of Chiba City neighbouring Tokyo. Being a tropical fish of the family Poecilidae native of South America, the guppy is known widely as a popular aquarium fish, and also as an efficient natural enemy of mosquitoes that breed in sewage waters. Previous observations in Japan have shown that the fish cannot survive outdoors over the freezing temperature during the winter season, but has established as wild colonies in sewage ditches in several hotspring areas, where the water temperature is maintained above 15℃ throughout the year. Yoshikawa is a small river of about 8km in length and 0.2/1,000 in the average slope. The upstream takes sewage water of public housing areas built in the outskirt of the city, and on the spot just before the river flows into the city a large quantity of underground water pumped up from natural gas wells is discharged continuously into the river. The well water has the temperature of about 30℃, and keeps the water temperature of its downstream not lower than 20℃ even during the winter season. The guppies were found to be breeding along the full length of the river during the summer season from July to October, but their distribution became restricted during the winter season to only the downstream of the natural gas well, or in the range where the water temperature was higher than 17℃. Seasonal observations of the chemical, physical and biological characters of the river water were carried out at three stations, at least four times a year. At the Station 2 located about 100m downstream of the inflow of the well-water, and at the Station 1 located 1.5km further downwards and in the business area of the city, the water temperature remained above 20℃ throughout the year and other chemical and biological characters were kept almost constant in these observations. The chlorine contents of samples collected from these stations were always very high due to the mixture of about the same amount of the well water showing the salinity as high as the sea water, but excellent reproduction of the guppies were seen in this zone. At the Station 3 located upstream of the well, the water temperature varied from the lowest of 11.5℃ during the winter season to the highest of 26.6℃ in the summer, and the guppies were found in these upstream zones only when the temperature was above 17.5℃. Results of both chemical and biological analysis of the water samples have shown that the river water was highly polluted, with BOD values from 6.5 to 20.7ppm and with the biological system of either beta-polysaprobic or alpha-mesosaprobic. The biological character of Station 1 and 2 remained fairly constant throughout the year, being beta-polysaprobic in the former and alpha-mesosaprobic in the latter, but that of the upstream zone at Station 3 was alpha-mesosaprobic during the summer season and beta-polysaprobic in winter in connection with the scanty rainfall of this season. It is a biologically interesting fact that a South American tropical fish is breeding enormously in a sewage ditch running through a modern city of the temperate zone, highly adapted to pollution of the water. In connection with the recent discovery by a group of Japanese scientists that the guppies are useful in the biological control of some mosquitoes and in the treatment of sewage waters, the ample supply of the fish from this natual breeding place located near Tokyo has made subsequent studies on this line much easier than before.

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The morphological characteristics in the terminal part of abdomen of Periplaneta fuliginosa (Serville) were studied from the newly emerged first instar nymph through the whole developing stages until adults. Except the first instar nymphs which were obtained escaping from the oothecae the specimens used for the present observations were collected by the bait traps set in a building. The morphological changes which took places during the course of developing could be traced into two directions, that is, one to female adult and another to male adult. The presence and the developing of a notch at the middle of hind margin of the ninth abdominal sternite as well as the styli growing on the ninth sternite, and the striking development of the seventh sternite were noticed in the specimens developing to females. With the specimens growing to males no notch was observed at the margin of the ninth sternite and either the eighth, the ninth sternites or the styli remained unreduced while developing. These characteristic features enabled the sexing of cockroach through the whole developing stages.

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The powers of survival of 4 species of cockroaches under a low temperature of 5.5±0.5℃ were investigated. No any stage of Periplaneta americana and Blattella germanica could tolerate the chilling treatment of 40 days. Nymphs of older instars of P. fuliginosa survived for 90 days and some oothecae for more than 80 days under the chilling treatment, when given an exposure to 15±1℃ beforehand. Most of nymphs and adults of P. japonica tolerated the chilling treatment for more than 90 days with the preliminary exposure. These results suggest that P. americana and B. germanica hardly survive the coldest 3 months outdoors or in unheated buildings in Central Japan, whereas P. fuliginosa and P. japonica tolerate the winter under outdoor conditions.

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An Austro-oriental cockroach genus Megamareta was discussed based on available material which includes the type-species and a Japanese representative, as well as several examples of an associated genus Onychostylus.

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Four species of Simuliidae, Simulium (Simulium) japonicum Matsumura, S. (Eusimulium) aureohirtum Brunetti, S. (E.) morisonoi n. sp. and S. (Gomphostilbia) tokarense n. sp., were collected in the Tokara Islands located between Kyushu and the Amami Islands. Both adult and immature stages of the new species are described in this paper.

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The effects of feeding nematodes to the mite, Macrocheles muscaedomesticae were observed under the laboratory conditions on its predatory efficiency for house fly eggs and also on its reproduction rate. A free-living nematode, Rhabditis elongata originally isolated from a pig manure was used in the experiments. It was shown that the more feeding of nematodes on the mite caused the less destruction of fly eggs by the mite. However the reproduction rate of the mite was remarkably enhanced by the feeding of nematodes.

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Larvicidal effects of some organophosphorus insecticides against the larvae of the biting midge, Culicoides circumscriptus KIEFFER, were tested at the tideland of Lake Saroma, Hokkaido. The insecticides used in this test were ABATE 5% emulsifiable concentrate (EC) and 1% granule (GR), Dursban 5% EC and 3% GR and Dowco-214 10% EC and 3% GR. In this field test, Dowco-214 was the most effective. There were little larvae at 35 days after treatment of Dowco-214 EC and GR when applied at the rate of 50mg and 90mg of active ingredients per square meter respectively. Application of Dursban 5% EC was fairly effective. Effect of ABATE against the larvae of this species was insufficient. In spite of dosage as much as 120mg per m^2 applied, heavy infestation of the larvae was ovserved as before. In mid-summer, vertical distribution of the larvae in the mud was observed. The majority of the larvae was found from the mud close to the tideland surface, and there were little larvae below the depth of 2cm.

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Laboratory tests were carried out on several single dose and anticoagulant rodenticides as a tracking powder against white mice and rats. In order to examine an attachability of the powder to a body surface, five 100 mesh powders, such as rice powder, starch, soybean powder, talc and silica gel were tested. Among them, rice powder attached to mice best, following starch, soybean powder and talc. The average powder weight attached was 0.5-0.7g per mouse in 15 second exposure. The tendency of effectiveness among the different powders containing 0.05% scilliroside which was contacted to the mouse coincided fairly with the order of attachability to the body mentioned above. In the test to examine the effect of rodenticides in the rice powder, the chemicals which gave the complete mortality in a time as short as 15-60 second were 0.05% scillirocide and 5% ANTU. The other chemicals also showed comparatively high mortality with the exception of 1% thallium sulphate. When powders containing single dose rodenticide were treated on a short runway which was made of tin plate, the mortality of rats was lower than that of mice exposed to the same powder. On the other hand, coumatetraryl, an anticoagulant rodenticide, showed 100% mortality in 3 to 7 days when 2g of 0.25% powder was treated on the runway in the area of 15×15cm.

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Discriminant function was applied to the morphological differentiation of adult females of autogenous Culex pipiens molestus (Cpm) from anautogenous C. p. pallens (Cpp) in Nagoya City, central Japan. 1) Measurements (or counts) were made of various parts of female mosquitoes, and the ten quantitative characters listed below were tested for the discrimination efficiency : (1) Ommatidal number (2) HS value of the horse shoe (3) Rc/Mc ratio (4) WL/Rs ratio (5) P/D ratio (6) Rc/Rs ratio (7) WL/Rc ratio (8) r/m ratio (9) WL/WW ratio (10) Mc/Ms ratio (Fig. 1). 2) It was difficult to discriminate Cpm from Cpp by any one of these characters because distribution intervals between the rejection limits. (α=0.05) more or less overlapped each other (Fig. 2,Table 1). 3) In order to evaluate the discrimination efficiency of the ten characters, discrimination index (DI) was obtained as follows : DI=d/A_p+A_m where d signified the difference between mean values of the same characters in Cpm and Cpp, A_p and A_m denoted Av alues calculated as follows for Cpp and Cpm, respectively. [numerical formula] u^2 : unbiased estimate of variance N : number of samples inspected F^1_<N-1> (0.05) : F value at a 5% level of significance for degree of freedom n_1=1,n_2=N-1 When the index for a certain character is over unity, this character can be used for the discrimination between Cpm and Cpp; and the larger the index, the more effective the discrimination by the character. However, the discrimination indices calculated for the ten characters ranged from a maximum value of 0.8954 (ommatidial number) to a minimum of 0.0297 (Mc/Ms ratio), revealing that any one of these was not good enough by itself. 4) Various discriminant functions were obtained when different number of characters were used. The critical points of the discriminant values were so fixed that α should be equal to β, where αsignified the probability of committing type I error in which Cpp might be mistaken for Cpm and β signified that of type II error in which Cpm might be mistaken for Cpp. As a result, the probability α (=β) was calculated to be about 2% when three characters. were used; and it decreased to about 1% when six characters were employed (Fig. 3,Table 3). 5) In the case of Cpp, there existed significant linear correlations between each of the seven characters out of the ten and wing length, which varied considerably with the breeding month (Fig. 4,Table 4). 6) The extent of the seasonal variations in the ten characters of Cpp was found to range from about 1 to 12% of the annual mean values (Table 5). But no significant differences were seen among the monthly averages of the discriminant values derived from the six characters : ommatidal number, Rc/Mc ratio, WL/Rs ratio, P/D ratio, R_C/R_R ratio and HS value.

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1) Field control tests against the fly larvae applying organophosphorus emulsions and granules to the privies were carried out from July to September, 1970,in Saitama Prefecture. 2) Larvicidal treatments of NK-1202,at the rate of 2 liters of 0.0125% emulsion or 10g of 3% granule per square meter, gave satisfactory effect, but the larvae appeared again in 7 days after the application. Exterminatory effect of the insectidides was the following sequence : NK-1202-Diazinon-Fenthion. 3) The control effect with granules proved to be higher than that of emulsions.

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Ovicidal activity of synthetic juvenile hormone analogues was evaluated for human body lice. Among five compounds tested, p-ethyl phenyl epoxy geranyl ether (Compound No. 5) was most effective in blocking embryonic development when the adults were continuously contacted to cotton pads impregnated with the compound, showing that the LD_<50> was about 27μg/(cm)^2. Contrary to the general conception that the JH has no effect on the survival of adult insects, many of lice continuously exposed to the SJHA could not survive for longer period than the controls. Mortality of the lice treated with 0.016 μg/(cm)^2 of Compound No. 5 exceeded by 50% at day 10. The results are of special interest to control the human body lice which has become resistant to all conventional insecticides.

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This paper describes the characterization of the skin reactive substances from the horse-fly, Tabanus iyoensis. 1. Strongly skin reactive substances were extracted from the thorax and the abdomen of adult female bodies. Activities both from the thorax and the abdomen distributed similarly in the further fractionation process, i.e. the gel filtration by various types of Sephadex and the chromatography by ionexchange Sephadex. 2. The active substances seemed to be non-dialyzable proteins which, in respect to the molecular weight, were subdivided into 2 categories, one having the M. W. of more than 200,000 and the other the M. W. of 50,000 to 100,000. This, with the results of the ion-exchange chromatography, suggests that several substances rather than a single one, which are not very toxic themselves, are related to the human skin reaction. 3. The agar gel diffusion between the abdomen extracts and the corresponding rabbit antiserum (an active fraction after the G-25 gel filtration was used for immunization) revealed at least 2 lines, of which the main line located toward the antibody side seemed to be unrelated to the skin reaction. In the experiments with the absorbed antiserum, however, the other line disappeared when the skin reactivity (activity L) was present in the fraction used for the absorption, indicating that there may be a close connection between them. 4. Neither a hemolytic substance observed in the abdomen extracts nor a pink-colored substance in the thorax extracts having an absorption maximum at 410mμ was related to the skin reactivity.

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[in Japanese]

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