Ecology of mosquitos (Diptera: Culicidae) at a site endemic with Japanese encephalitis on Luzon, Republic of the Philippines.

A 2-year study of the ecology of mosquitos was conducted in a rice-growing area in the Philippines. Forty-four species in 8 genera were collected using 6 techniques, with Culex vishnui being most abundant. Of all the Anopheles collected, most species were exophagic, while most of the Culex species collected were endophagic. Anthropophilic or zoophilic feeding patterns were estimated using man-to-animal biting ratios. Peak periods of mosquito abundance occurred several months after the onset of both the rainy season and the rice irrigation period. Seasonal populations of the more abundant species revealed 3 distinct patterns: 1) populations are high during the rainy season and low during the irrigation period; 2) populations are equally strong during both periods; and 3) populations are highest during the irrigation period. Species' biting activity was grouped into 2 patterns: 1) those that feed primarily from 1800-0000; and 2) those that feed evenly throughout the night. Mosquito abundance and Japanese encephalitis virus activity were related to rainfall and rice-growing practices.