Effect Of Organic Rice Farming On The Seasonal Occurrence Of Aquatic Animals And Predation Efficacy Of The Muddy Laoch Against Mosquitoes In Rice Field

Culex tritaeniorhynchus Dyar and Anopheles sinensis Wiedemann are distributed widely in Korea and are vectors of JE and of both malaria and inland filariasis, respectively. These mosquitoes are particularly abundant in riceland agroecosystems, where they breed in irrigated rice fields and associated lowland areas. Anopheles sinensis and Cx. tritaeniorhynchus are the predominant bloodseeking mosquitoes in July and August, respectively (Shim et al. 1987, 1990, 1997) and, when present in large numbers, these species present a serious threat to human and animal health through annoyance and as vectors of disease. Because of the threat that An. sinensis and Cx. tritaeniorhynchus pose to human and animal health, there is a need to develop management programs that will serve to continually keep populations of these species at acceptably low levels. The development and implementation of such programs require a detailed study of the relationship between environmental factors, including natural enemies and various abiotic factors in ecosystems, and the ecology of these mosquitoes. Traditional mosquito control strategies in conventionally-farmed rice fields used mainly adulticides which include fogging, aerosol sprays and larval control from agro-pesticides in Korea (Ree et al. 1981, Shim et al. 1995a and b). Each of these methods involves the application of relatively large amounts of insecticides into the environment of the rice ecosystems. These methods also may deposit insecticidal residues in rice that can be taken inadvertently by consumers as well as farmers. Therefore, environmental concerns have stimulated other farming methods to reduce the use of insecticides for controlling pests in rice fields. One approach that has recently gained popularity is organic farming. In Korea, 0.08% of farmers cultivate several crops using organic farming, which utilizes organic fertilizers instead of chemical fertilizers and which does not use pesticides (Paek 1992).