The distribution of the Norway rat, Rattus norvegicus, extends from the subarctic and subantarctic zones to the tropics yet is limited by several factors. I discuss the limiting factors based on surveys in the subarctic zone (Yururi-Moyururi, uninhabited islands in Hokkaido), the temperate zone (a business district in Yokohama and an uninhabited islet, Kaiho-2 in Tokyo Bay), the subtropics (the Hahajima Islands in the Ogasawara Archipelago), and the tropics (Bangkok and Chanthaburi, Thailand). In Yururi-Moyururi, the rats recruited in the group under snow cover and in the summer. In Yokohama, the recruitment peeks fluctuated from year to year. In Kaiho-2, rats stopped recruiting in the winter because of dehydration, and the overwintered group lost body mass as a result of body fat consumption. In Hahajima, rats lost body mass and preyed mainly on plant matter because of chronic dehydration. In cities in Thailand, rats likely thrived by preying on food sources in water systems. I conclude that protein-rich diets and water balance are basic factors in the distribution of the Norway rat, as shown in the results for Kaiho-2 and Hahajima.
Three human cases of tick bite were examined to investigate the occurrence of spotted fever group (SFG) rickettsia in Akita Prefecture. The first case was a 36-year-old male in 1995 with SFG rickettsiosis-like symptoms, such as fever, rash and eschar, who was strongly suspected of being bitten by an adult tick but the tick species was unidentified. Although the etiology remained undetermined at that time, spotted fever group rickettsia infection was definitely diagnosed based on serological diagnosis in 2015. The second case was a 69-year-old female in 2014, and the third one was a 75-year-old female in 2016. They were bitten by a single female tick of Ixodes monospinosus, with Rickettsia helvetica identified genetically. The ticks of both cases were removed early (within 2 days) after tick bite and the patients were administered minocycline prophylactically. They showed no SFG rickettsiosis-like symptoms. Since a patient of SFG rickettsiosis and two R. helvetica-gene positive ticks have been found in Akita Prefecture, the actual situation should be elucidated to take measures in the future.
In order to control adult blackflies in the upper reaches of the Ukawa River in Kashiwazaki City, Niigata Prefecture, the present study was conducted on the species composition and densities of adult female blackflies attracted to humans at a total of 22 sites in four areas in the upper reaches of the Ukawa River Basin from June to October in 2013. A total of 2,195 individual adult blackflies were captured from all sampling sites during the investigation periods. The average number of blackflies per site was 11.0 individuals/2 investigators·10 minutes. Noda was the highest capture area where we could collect 13.5 individuals/2 investigators·10 minutes, followed by the Joujou Area. The fewest captures were in the Ukawa Area (8.9 individuals/2 investigators·10 minutes). The dominant species was Simulium (Simulium) arakawae Matsumura, 1915 (397 total individuals, 99.5%), followed by Simulium (Simulium) oitanum (Shiraki, 1935) (2, 0.5%). The daily biting activity of female adult blackflies observed every two hours from 6:00 to 20:00 at four areas on August 10, 2013 peaked at 16:00–18:00 (range from 62.5 to 89.1%, average±S.D. 75.0±11.0%).
The collection of Sarcophagidae made by the first author during the surveys on flies of medical and forensic importance in Thailand from 2012 to 2016 is dealt with. A total 31 genera and 86 species of the flesh flies are listed. One new genus Komisca gen. nov. is established for Sarcophaga (s. lat.) nanensis Chaiwang, Sukontason & Sukontason, 2009. One little known species, Burmanomyia aureomarginata (Shinonaga & Tumrasvin, 1979) n. com., is redescribed and illustrated. Revised identification keys to the species of Thai Sarcophagidae are provided to include the new genus and three newly recorded species discovered after the last work (Kurahashi & Chaiwong, 2013). General morphology, terminology and definition are provided for keys and redescription.
We conducted a nationwide bedbug surveys in 2016–2017. A total of 101 specimens from 19 prefectures was collected in the investigations. Cimex hemipterus was recorded for the first time in Tokyo in 2016. The species was found in a highly air-tight building, with a constant elevated room temperature therefore, possibly providing an overwintering habitat. The results suggested that C. hemipterus abundance increased in various parts of Japan, with an increase of both Japanese and other tourists.