Habitat size: a factor determining the opportunity for encounters between mosquito larvae and aquatic predators

Occurrence patterns of mosquito immatures and insect predators in containers of various sizes were surveyed in summer (June-July) and autumn (September) of 1998 in a rural area of Saga, southwestern Japan. Mosquitoes were categorized into three types in relation to habitat size. First, Aedes (Stegomyia) spp. and Tripteroides bambusa occurred mostly in small containers of < 0.1 m2. Second, Ae. japonicus and Culex kyotoensis occurred in larger container sizes, compared with the first group. Third, Cx. tritaeniorhynchus and Anopheles sinensis occurred in rice fields in summer and in large containers in the autumn. Predators such as Notonectidae, Anisoptera nymphs, and Chaoborus sp. and a predaceous mosquito Cx. halifaxii occurred mainly in large (> or = 0.1 m2) containers. The mosquitoes of the third group showed similarities with predators in the occurrence of each habitat type, and they frequently co-occurred with predators. The mosquitoes of the first group showed less similarity with predators in habitat type preference, and they rarely co-occurred with predators. The second group mosquitoes showed intermediate patterns of the first and the third groups.