Atcharaporn Somparn

Using Zooplankton, Moina Micrura Kurz to Evaluate the Ecotoxicology of Pesticides Used in Paddy Fields of Thailand

Thailand is an agricultural country where agriculture is a very important part of the economy. Thailand expanded exports of agricultural products and also imports fertilizers and pesticides intensively. Pesticides are used widely in agriculture and trade of agricultural products to increase agricultural yield and to protect plant from diseases, weeds and insect damage (Department of Agricultural, 2010). Since pesticides were first imported into Thailand under the “Green Revolution Policy” as part of the 1st National Economic and Social Development Plan in 1966, the total amount of imported pesticides has dramatically increased year by year. Most pesticides used in the country are imported (Department of Pollution Control, 2005), and the quantities of imported agricultural pesticides have increased 3 times from 1994 to 2005, reaching more than 80 thousand tonnes in 2004. Pesticides are applied in the highest quantity in vegetable and fruit farming, where market pressure for appearance is higher. In 2000, organophosphates contributed the majority of imported pesticides followed by carbonates and organochlorines; most were herbicides, followed by insecticides, disease control agents and plant growth regulators (Department of Pollution Control, 2002). The result from increasing pesticides uses has resulted in significant increased crop contamination and human health hazard (Office of Epidemiological, 2009). The risk of pesticide contamination in fruits and vegetables in Thai market often occurs. Rice is the major crop and food source for most Asian countries including Thailand. Rice production from paddy fields faces variety of pests that require a range of pesticides and herbicides to manage the presence of insects and weeds, as well as fungal and bacterial pathogens. Indeed, losses of the total world rice crop due to insects have been estimated to occur at a rate of 28% per annum, which is four times greater than the average for other world cereal crops. More than 90% of the global end-user market in pesticides for rice production is applied in Asia (Abdullah, 1995). In Thailand, pesticides play an important part and widely use on rice production because its benefits in pest control and increased rice production. Therefore, pesticide contamination in draining water from paddy field has been one of non-point source pollution in aquatic ecosystem (Sanchez et al., 2006).