Effects of pesticide use in rice fields on birds

Abstract

Waterbird use of agricultural wetlands has increased as natural wetlands have declined. Use of rice (Oryza sativa) habitats by some waterbird species is considered essential to sustaining populations. Although use of rice habitats by waterbirds has been documented throughout the world, little information is available on potential risks as a result of chemicals used in rice cultivation. The current review summarizes understanding of the use and consequences to birds of pesticide applications in rice habitats. Historically, organochlorine pesticides known to be applied for pest management in rice cultivation included dichlorodiphenyltrichloroethane (DDT), aldrin, dieldrin, endrin, heptachlor, technical hexachlorocyclohexane (HCH), toxaphene, endosulfan and sodium pentachlorophenate. Endosulfan and purified HCH (the gamma isomer lindane) are still in use. Cholinesterase-inhibiting insecticides currently used in rice include carbofuran, monocrotophos, phorate, diazinon, fenthion, phosphamidon, methyl parathion and azinphos-methylmany products known to cause acute poisoning in birds. In addition, herbicides, fungicides, molluscicides and other pesticide types are used in rice cultivation. Some of the chemicals are highly toxic to birds and associated with mortality; several have the potential of causing adverse reproductive effects. Because of the large area under rice cultivation worldwide, the volume of pesticides applied to rice fields is significant. Innovations within the past few decades in rice production have increased pesticide use resulting in biodiversity losses in production areas and pollution of water resources. Management practices that address adverse effects of pesticide use in rice fields include increased adoption of Integrated Pest Management principles and less toxic products.