Air curtains have frequently been used in various food-processing plants to prevent insect invasion from outdoor environments. This study was conducted to evaluate the inhibitory effect of three types of air curtains against flying insects or wandering arthropods in field tests. Very few small flies such as Chironomidae or Sciaridae passed indoors through the air curtains during the daytime or nighttime. For large insects, however, Sarcophagidae and Calliphoridae passed through the air curtains in the daytime, and Lepidoptera and Coleoptera passed through the air curtains in the nighttime. There were relatively fewer wandering arthropods such as Orthoptera, Formicidae or Porcellio scaber than flying insects, and the air curtains' effect against wandering arthropods seemed to be lower than against flying insects. The cross-wise air curtain was more effective than the cross-wise circulating air curtain or the down flowing air curtain, especially against flying insects during the nighttime.

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Culex pipiens complex mosquitoes were collected to clarify their geographical distributions and seasonal abundance in urban Yokohama. Dry-ice light traps were set to collect adult mosquitoes in three residential districts from March 2006 to January 2008. Culex pipiens complex was classified into two subspecies, C.p. pallens and C.p. molestus by counting the number of individual eyes in the fifth line of the adult female compound eyes and measuring the D/V ratio of the adult male genitalia. In Naka ward, 72.5% of the adult female C.p. complex was determined to be C.p. molestus in 2006, whereas 65.3% (417/639) was determined to be so in 2007. However, the ratios of C.p. molestus among the male C.p. complex captured in Naka ward were 12.3% in 2006 and 9.3% in 2007. In Minami ward, the number of captured males was so small that the identification of the two subspecies was obtained only for the females; the result indicated that the ratio of C.p. molestus was 32.2% in 2006 and 25.7% in 2007. In the Institute of Health (Isogo ward), where insects were collected in the yard, 23.8% of the females and 5.9% of the males were C.p. molestus in 2006, whereas 13.5% of the females and 2.4% of the males were C.p. molestus in 2007. This suggested that the distribution of the adult females should also be identified for precise monitoring, since there appeared to be too few adult males in some districts.

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We electrically shocked chironomid larvae and pupae under laboratory conditions and calculated the mortality in order to establish a method of physically controlling them. Larval mortalities increased in proportion to the number of times 180V direct current electricity (DC) was turned on. Mortalities were low with an alternating current (AC) of the same voltage. However, applying 260V AC increased mortalities proportionally to the number of times the AC was switched on or off. Applying 260V AC for 15 seconds produced approximately 50% mortalities, but frequencies of 20 through 190Hz had no influence. In these studies, no significant differences in mortalities were observed between larvae and pupae.

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Petri dishes with humidified vermiculite containing Japanese subterranean termites, Reticulitermes speratus, or dark brown ants, Lasius japonicus, were kept at room conditions without heating for four winter months in Sapporo City, and mortalities of both species were monitored. Accumulated mortalities of the ants increased by 50.4% followed by 37.6% for termites with food and 26.2% for termites without food by the end of experiment (mixed conditions: non-aggregated and aggregated). The mortality in the aggregated conditions of termites without food was only 3.7%, and none of the ants died (0 mortality; all survived). In contrast, 37.6% of termites with food died as did 84% of the ants in the non-aggregated conditions. Aggregation thus seems to be an important behavior for both species in cold seasons.

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A semi-field test and field tests were conducted in supposition of vector control using two insecticides against mosquitoes. Spraying with chlorpyrifos-methyl 10% EC diluted 500:1 in water was effective against Culex pipiens pallens Coquillett and Armigeres subalbatus (Coquillett) up to 250ml per square meter in the semi-field test. phenothrin 10% EC diluted 4:1 was also effective against both pest species in ULV treatment at 2l/m². Outdoor treatments with chlorpyrifos-methyl EC and phenothrin EC against four species of mosquito including C. pipiens and A. subalbatus were effective in the same dosage as in the semi-field tests. Leafy plants such as Epipremnum aureum Bunt and Spathiphyllum wallisii Regel were damaged by chlorpyrifos-methy EC diluted 10 through 200 times. However, the plants were not influenced by phenothrin EC diluted 4:1 in ULV treatment. Labor time and cost were also checked in the field tests for the two chemicals; phenothrin was found to be much more expensive than chlorpyrifos-methyl EC.

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[in Japanese]

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