徳島市の防蚊活動について

The city of Tokushima, standing at the mouth of the river Yoshino in Shikoku Island, islowland barely at the sea level. The city has long been the site of massive occurrence ofmosquitoes (Aedes dorsalis, Culex tritaenorhynchus, Pipiens molestus, Aedes albopictus, and Culexpipiens pallens Coquillett) and the epidemic of Japanese encephalitis was prevalent. Some 30years ago, Tokushima City Medical Association established Insect Pest Research Institute(Shinya Okubo, M. D., Director) to combat mosquitoes.Three measures have been employed against the occurrence of mosquitoes.１）Mosquito fish (topminnow, Gambusia affinis)Upon the suggestion of Professor Manabu Sassa (Medical Science Research Institute,The University of Tokyo), mosquito fish was brought from Tokyo and discharged intorivers, paddy fields and ditches of Tokushima area. Mosquito fish, preying upon wiggler,has very effectively reduced the occurrence of mosquitoes. Since the fish is rather frailto low temperature and has many natural enemies, annual discharges are necessary.２）Juvenile hormone (methoprene Altosid 10F, Earth Biochemical-Otsuka)Some ditches are not suitable for mosquito fish discharge because of low oxygen concentrationin polluted water. Application of juvenile hormone (methoprene) is a veryeffective means to inhibit transformation of wigglers into mosquitoes.３）Mosquitocidal liquid (Earth Biochemical-Otsuka)For the control of imaginal mosquitoes, a newly developed mosquitocidal liquid is beingapplied.With the application of these measures, either individually or in combinations, for thepast 30 years, we have succeeded in controlling mosquitoes in Tokushima area. Togetherwith other public health activities, our mosquito control program has significantly contributedtoward the virtual eradication of Japanese encephalitis in the area.