Over 5 years surveys on the food habits of 'Habu', poisonous snake, in nature in the Amami Islands were carried out since September of 1959 and the results were summarized as follows : 1. 927 cases were examined and these animals as food of Habu in nature belong in 43 species, 38 genera and 27 families of whole classes of Vertebrata, i. e. 85.9% of them belonged in Mammal, 6.6% of birds, 4.9% of Reptile, 2.5% of Amphibia and 0.2% of Pisces. 2. 17 species of animals were newly found as the food of Habu. 3. House rats and water rats occupied of 82.5% of whole cases examined and the author believes that the house rat is very important one as the food of Habu. 4. Main food of young snake was cold-blooded animals as Reptile and that of adult was warm-blooded animals, especially house-rats. 5. Rats occupy majority of food all year round but the rate of bird becomes higher in autumn. 6. Territory of Habu varies in wide range from field to around residence area and Habu likes house rats so much that residence area must be dangerous zone of chance of Habu attack. 7. Nocturnal activity of Habu and its activity of climbing tree and invasion to residence were proved by its food habits. 8. Sizes of food vary by size of snake and sometimes its takes same size of food as its own body length. 9. Foods are swallowed from head and also digested from there. 10. New knowledges on taxonomy and ecology of food animals were obtained from these series of surveys.

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[in Japanese]

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Three species of Rhadinopsylla from Hokkaido and their hosts are reported. They are Rhadinopsylla (Actenophthalmus) japonica from Pteromys volans orii, Rhadinopsylla (Actenophthalmus) ohnoi and Rhadinopsylla (Actenophthalmus) alphabetica taken mainly from Clethrionomys rufocanus bedfordiae. The occurrence of R. ohnoi in Hokkaido is recorded here for the first time.

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Recently, a grain itch caused by mites in autumn became a serious problem in barley storehouses in the central part of Japan. The authors investigated some storehouses in the district of Mito where the most severe itch patients were observed from 1960 to 1965. The mite species found are Pyemotes ventricosus (Newport), Cheletomorpha lepidoptorum (Shaw), Cunaxa sp. and Leiodinychus sp. Among them, P. ventricosus and C. lepidoptorum were the most abundant species on the surface of straw-bags containing barley grain and undoubtedly responsible for the itch. Not only the porters carrying strawbag on their shoulders but also incidental passengers walking through the storehouses were attacked by mites. The symtoms are very similar to that described by Booth & Jones (1952) for a grain itch which burst at Indiana in 1950-1951. The only difference is the shorter incubation time before the appearance of symtoms (6〜8 hours). The main hosts and preys of the two mite species seem to be Lepinotus reticulatus Enderlein, Liposcelis sp., Sitophilus oryzae Linne and some free-living Acari (Leiodinychus sp. etc.). It is interest to note that ungorged females of P. ventricosus occasionally form a mass on the surface of straw-bag, though the meaning of this habit is quite uncertain. This assemblage is observed in the form of an orangecolored spot of 7〜8cm in diameter. Each spot may consist of more than 300, 000 individuals of pyemotids. In the case that the color of the spot is pale-pink, more than a half of mites involved are dead. Is it impossible that the phenomenon is due to their cannibalism?

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Cross-breeding experiments between molestus (autogenous) and pallens (anautogenous) strains of Culex pipiens sensu latu were carried out by using genetic markers Gr (green larva) or Or (orange larva) in colonies established from naturally occurring mutants as the weaus for investigating their copulation habits. 1. In the crosses between Or-females and Ormales plus Gr-males, 13% of the egg rafts produced larvae showing mixture of the two different colour characteristics of Or and Mix, which indicated that their mothers were inseminated by at least two males with different genetic markers. This fact suggests that females of Culex pipiens s. l. can copulate with two or more males and their offspring from the same egg raft may have different fathers. 2. In the crosses of pallens-females with Gr-males plus pallens-males in the same cages or of Gr-females with Gr-males and pallens-males, it was also demonstrated through hatchability of egg rafts and by larval colour characters that pallens or Gr females sometimes copulate with both pallens and Gr males, and can produce mixed larval colonies with different fathers. 3. In the mixed crosses of Gr-females plus pallens-females and Gr-males plus pallens-males, 6.3% of egg rafts deposited by pallens-females were composed of a mixture of eggs inseminated by both pallens and Gr males. 4. In the mixed crossing experiments between males and females or different forms belonging to the same age groups, selection in copulation between the same forms were observed. However, in the mixed crosses of same and different forms copulated with males of different ages, i. e. those emerged one and eight days before, the females were found to more frequently copulate with younger males, irrespective of the form to which this belonged.

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Experiments were carried out to determine the influence of rearing conditions of larva on the development, body size, and autogeny of the autogenous mosquitoes, Culex pipiens molestus. The following quantities of food were available for larvae : 2.5mg 5.0mg, 10.0mg, 20.0mg, and 40.0mg, per larva. Developmental rate of the larvae increased with larger amounts of food. The mean developmental times from first inster larvae to pupae were 13.9 days with 2.5mg food per larva, and 7.4 days with 40.0mg per larva (Fig.1). The pupation rate and emergence rate of mosquitoes showed their maximum percentages at 10.0mg of food per larva (Fig.4). The autogeny rate of each group of the mosquito was recorded by the number of females with fully developed eggs (stage IV) in their ovaries per total number of females dissected. The autogenous character in this strain of the mosquito was found to be more strongly influenced by the genetical background rather than the nutritional conditions. The autogeny rates of series fed 40.0mg and 20.0mg per larva were 100%. These rates of series fed 10.0mg and 5.0mg per larva did not drop below 80%. Only three females emerged among those larva fed the minimum amount of food (2.5mg/larva), but all were autogenous females. Wing length of the adults emerged from the lots reared under different nutritional conditions was measured as an indication of the size of the mosquitoes. The wing lengths of mosquitoes increased in the following order : males<anautogenous femles<autogenous females. In each group, the wing length increased progressively when greater amounts of food were available (Fig.5).

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The authors confirmed that a aquarium fish of South America, guppy (Lebistes reticulatus Peters) has been acclimatized in the sewages of hot spring water of Rendaiji (N34°42′, E138°12′), Asama (N36°15′, E138°00′), Togura-Kamiyamada (N36°29′, E138°05′) and Uchigo (N37°02′, E140°51′) from several years ago. Regular surveys of the guppy populations and the enviromental factors of habitats were mainly made in Togura-Kamiyamada and Rendaiji. Water temperature of the habitats of guppies was maintained about 20℃ even in winter season. These guppies were not cold-resistant. They begin to disperse to irrigation streams, rice fields and shallows of rivers in summer. In one of the winter habitats population density of guppy attained to extreme high level until end of winter, but it remarcably decreased in summer as dispersion of fish proceeded. The guppies showed so rapid growth and so great fecundity that they could fill the summer habitats in shorter time. It can be supposed that guppy is suitable to be used as a predator of mosquito larvae which emerge in rice fields and other smaller water bodies by the reason of its euryphagy and rapid increase in number. In the rice fields of Rendaiji and Togura-Kamiyamada, very little larvae of Anopheles sinensis and Culex tritaeniorhynchus were discovered.

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Investigations were made to find out the cause of inactivation of some organophosphorous insecticides after mixed with polluted water. Fourth instar larvae of the mosquito, Culex pipiens pallens, DK strain, were used for test of the effectiveness of the insecticides. Results of experiments to expose the larvae at 28℃ for 24 hours to buffer solutions with various pH values have shown that 50% levels were 11.8 and 2.4 and no deaths were seen between pH 3 and pH 10. Further tests were made on the residual effects of insecticides mixed in buffer solutions with varying pH values from 3 to 10. At the observations made after 16 days, no considerable reduction in the effectiveness was seen for dieldrin, lindane, p-p' DDT, fenthion (Baytex), fenitrothion (Sumithion), parathion and methyl-parathion, while remarkable reductions in effectiveness were seen at all pH levels for ronnel, at alcaline solutions over 7 for dichlorovos (DDVP) and malathion, and at acid solutions below 4 for diazinon. The loss of activity of some insecticides when mixed with polluted water discussed below is therefore considered not due to the direct effect of hydrogen ion concentrations. Experiments were carried out to see the effects of bacterial growth in media containing insecticides. The insecticidal activity of parathion, methylparathion and fenitothion was found to be remerkably reduced or almost completely lost within 4 days when these were mixed into polluted water prepared with a animal food from natural environments or into unsterilized bacterial culture media such as 1.0% peptone solution. The media containing pure culture of Bacillus subtilis was found to cause the same inactivating effects on the insecticides, while the insecticidal activity was kept unchanged when these were mixed after the media had been sterilized. Both fenthion and diazinon were stable under the same condition and no reduction in the effectiveness was seen for a period of 16 days. The above inactivation of some insecticides in polluted waters was found to be due to bacterial decomposition of substances non-toxic or less toxic to the insects. For example, Bacillus subtilis was demonstrated to decompose parathion to amino-parathion, and fenitrothion to amino-fenitrothon or to methylparathion and further to aminomethylparathion. LC 50 levels against C. p. pallens larvae of amino-parathion, amino-methylparathion and amino-fenitrothion were estimated to be 5.37, 60.3 and 115 ppm., respectively. The chemical structures of amino-parathion, amino-methylparathion and amino-fenitrothion are O, O-diethyl O-para-aminophenyl phosphorothioate, and O, O-dimethyl O-(3-methyl-4-aminophenyl) phosphorothioate, respectively.

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A screening method of cockroach repellents was described. A filter paper (Toyo No.2., 10×9.6cm) impregnated with repellent at one prescribed concentration was set into a paper tube (10cm long by 3.0cm in diameter). The paper tubes were placed in a plastic cage (30×23×6cm), and then 50 adults of the German cockroach, Blattela germanica L., were released. Repellency was evaluated from number of the roaches in tube after 24 hours as follows; Repellency (%)={(Number of roaches in untreated tube)-(Number of roaches in treated tube)}×100/(Number of roaches in untreated tube).

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During a period of June and July, 1965, there was a great outbreak of housefly in the dump site, Yumenoshima Island, Tokyo. An enormous number of these flies supposingly moved to shopping districts and became a great annoyance. On topical application, these flies taken from "Yumenoshima" proved to be highly resistant not only to DDT and γ-BHC, but also to organophosphorus insecticides such as malathion and diazinon. On the other hand, they showed only slight crossresistance against the other organophosphorus insecticides, DDVP, Baytex (fenthion) and Sumithion (fenitrothion). The larvae of the same colony were also resistant to malathion, but still susceptible to Baytex, Sumithion and DDVP.

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In order to know the contact toxicity of several insecticides against common millepede, Orthomorpha (K.) gracilis C. L. Koch, a seris of tests were carried out under laboratory conditions. Seven emulsions of insecticides, DDT, lindane, dieldrin, diazinon, DDVP, Baytex and Sumithion were tested through residue contact method using impregnated filter papers in various concentrations. As a result of the experiments, it was confirmed by LC-50 values after 24 hours of treatment that lindane is the most effective restult showing LC-50 value 2.3ppm and the others are successively effective in the following order : DDVP, diazinon, Baytex, Sumithion, dieldrin and DDT. LC-50 value of DDT was 1, 740 times of lindane emulsion.

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Effects of fenitrothion, malathion, lindane, dieldrin, diazinon, fenthion, chlordane and dichlorvos were evaluated by exposing Millipedes, Oxidus gracilis (Koch) to the residues of toxicants for 15 min., 1 hours or 7 days. The toxicants were applied with acetone solution containing 5% of the insecticides on filter paper at a ratio of 50ml per square meter. In these experiments the most effective insecticide was dichlorvos with the following in descending order : fenitrothion, diazinon, malathion and fenthion. Chlordane, lindane, malathion and dieldrin were found to be ineffective for the control of this pest.

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