Mosquito fauna in water-holding containers with emphasis on dengue vectors (Diptera: Culicidae) in Chungho, Taipei County, Taiwan

A survey was conducted to characterize the mosquito fauna in water-holding containers in residential and open areas with emphasis on Aedes albopictus Skuse, and to determine the prevalence of mosquito-positive containers to obtain background information for a source reduction program. Seven container-inhabiting mosquito species were collected in residential areas, including Ae. albopictus, Culex quinquefasciatus Say, C. pallidothorax Theobald, C. neomimulus Lien, C. bicornutus Theobald, C. fuscanus Wiedemann, and Tripteroides aranoides Theobald. Ae. albopictus was the most abundant species and was collected in 18.49% of the containers examined. Other mosquito species were found in 0.02-0.16% of the total numbers of water containers checked. Of the positive water containers, 97.33% contained Ae. albopictus larvae. Sixteen species were collected in open areas away from residential sites. Ae. albopictus was most abundant and was present in 24.50% of the total number of containers examined. C. bicornutus, C. quinquefasciatus, and C. pallidothorax were present in 2.17, 1.48, and 1.08%, respectively. Ae. albopictus larvae were found in 74.78% of the mosquito-positive water containers. The mean Breteau index (+/-SE) in 1997 (17.22 +/- 1.59 mosquito-positive containers per 100 premises) per village in residential areas was not significantly higher than the index in 1996 (16.86 +/- 1.33). The frequency of occurrence of Ae. albopictus in different containers is presented. A greater preference for containers in outdoor habitats was found. The ratio of the total number of containers indoors and outdoors per premises was 1.15:1.00, whereas the ratio of mosquito-positive containers indoors and outdoors was 1.00:1.83. Most indoor breeding containers (86.11%) in residential areas were used for planting purposes and for recreation (12.50%). The number of breeding containers in residential areas that were classified as trash increased from 0.35% indoor to 39.03% outdoor, whereas the number used for planting reduced to 34.95%. Most breeding containers (63.02%) in open areas were trash; natural containers (11.86%) were the 2nd most common breeding site followed by temporarily unused (8.84%), watering (6.98%), and planting containers (5.81%).