The chironomid faunae in slow sand filter beds of filtration plants were investigated and compared between southwestern Japan, i.e., the Sakishima Islands (Ishigaki and Miyako Islands), and a plateau area, i.e., Honshu Island (Nagano Prefecture). As a result, the midge fauna was found to be dominated by two species (in order of abundance), Polypedilum nubifer (Skuse) and Cricotopus trifasciatus (Panzer) at Someya filtration plant in Nagano Prefecture. On the other hand, in the Ishigaki filtration plant, the most abundant species was Hanochironomus tumerestylus Ree, followed by P. nubifer which was also collected at Nagano Prefecture. Moreover, in Sodeyama filtration plant located in Miyako Island, the most abundant species was Cryptochironomus javae Kieffer, followed by Polypedilum nodosum (Johannsen). P. nubifer, Cricotopus bicinctus (Meigen) and Ablabesmyia moniliformis Fittkau were common species in all plants. The most important factor influencing the abundance of chironomid fauna supposedly is the water temperature in the slow sand filter beds.

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The authors discussed the effect of bait formulation containing coumatetralyl of 0.025% and 0.0375% on warfarin-resistant and susceptible roof rats, Rattus rattus, and wild roof rats caught in Shinjuku Ward, Tokyo, Japan.

When 0.025% and 0.0375% toxic baits of coumatetralyl were given respectively to the warfarin-resistant roof rat, there was a significant difference (P<0.05) in mortality and bait intake between the two test groups. With an increase in coumatetralyl concentration, the effect was substantial even to the warfarin-resistant group. It was evident that coumatetralyl exceed efficacy than warfarin at the same concentration.

When 0.025% and 0.0375% toxic baits of coumatetralyl were given to the warfarin-susceptible group, there was no significant difference in mortality and bait intake. It was not essential to increase the coumatetralyl concentration in case of the warfarin-susceptible roof rat and coumatetralyl was effective at the low concentration. When 0.025% toxic bait of coumatetralyl was given to the wild rats caught in Shinjuku Ward, Tokyo, the results were similar to that of the 0.025% test group of warfarin-resistant rat in lethal feeding period and bait intake. It was proved that those rats exhibited high resistance to warfarin.

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Attractiveness of a high-pressure sodium lamp to photo-positive flying insects in comparison with a mercury lamp was investigated in a factory yard. The ultra-violet emission from the high-pressure sodium lamp was about 1/60 to as much as that of the mercury lamp. The lamps were mounted on the tips of 4 pillars of 5.7m height and located more than 28m away from each other. The difference of attractiveness was measured by the number of captured insects on the sticky traps set closely near and 5m below to the lamps. The high-pressure sodium lamp was about 50% less attractive than the mercury lamp. The number of insects around the entrances of the factory buildings was also determined by sticky traps under illumination of the mercury or high-pressure sodium lamps. The trap catches of insects decreased when illumination was changed from the mercury to high-pressure sodium lamp. No competition in attractiveness to insects among the lamps was observed even when the two kinds of lamps were used at the same time. The effect of the change of the lamps was different among insect groups. The trap catches of Lepidoptera, Hymenoptera, Hemiptera and Coleoptera insects more remarkably decreased than those of Diptera insects when mercury lamps were replaced to high-pressure sodium ones.

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Mosquitoes were collected in 20 parks in Yokohama to elucidate the seasonal and local distribution, as a part of research to survey the invasion of West Nile virus into Yokohama. CDC light traps combined dry ice were settled to gather adult mosquitoes in each 18 parks of 18 wards, and two parks in the harbor area during the period from July to November, 2003. The total number of mosquitoes was 2,242, and they were divided into 7 genera, 12 species. The dominant species captured were Culex pipiens complex (68.6%), followed by Aedes albopictus (24.3%). Culex pipiens complex was observed in each of 20 parks throughout the research period, but number of individuals exceeded in harbor area.

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Mixed-Cayenne-Pepper (Shichimitokarashi), a dried and powdered spice mixture containing chili pepper that is used to flavor Japanese cuisine, is often infested by Plodia interpunctella (Hübner). The purpose of this study was to investigate the growth and developmental period of P. interpunctella when reared on rice bran, Mixed-Cayenne-Pepper and in each of seven ingredients that comprise Mixed-Cayenne-Pepper (chili pepper, black sesame seed, orange peel, Japanese pepper, hemp seed, poppy seed and seaweed). Different densities (5, 10 and 50) of newly emerged first-instar larvae of P. interpunctella were placed in plastic containers (11cm in diameter, 6.5cm deep) containing 30g of each material. The containers were kept at 25℃, 70% r.h. and 16L8D. The first-instar larvae developed into adults in rice bran, Mixed-Cayenne-Pepper, black sesame seed, orange peel, hemp seed, and poppy seed, but none developed in chili pepper, Japanese pepper or seaweed. The survival rate was highest in rice bran, and the larvae developed into adults 2-3 weeks earlier than in the other materials. These results indicate that P. interpunctella larvae develop in Mixed-Cayenne-Pepper by selectively eating those ingredients which, although not ideal, are harmless for their growth and development.

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