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The role of pesticides in the SE Asian rice IPM: A view from the Mekong Delta

| July 11, 2016

Abstract:

Pesticide application remains an important component of rice pest management in Viêt Nam and responsible use should be integrated back into a strategy of good agricultural practices.

Three examples of important natural enemies: (left) a ‘generalist’ lynx spider predator, Oxyopes sp.; (centre) a parasitoid of the rice leaf-folder, Braconidae; (right) a pathogen, Metarhizium infected BPH. (Photo courtesy Trịnh Thị Xuân, Cần Thơ University)

Three examples of important natural enemies: (left) a ‘generalist’ lynx spider predator, Oxyopes sp.; (centre) a parasitoid of the rice leaf-folder, Braconidae; (right) a pathogen, Metarhizium infected BPH. (Photo courtesy Trịnh Thị Xuân, Cần Thơ University)

Crucial skills that need to be fostered include: better product selection with safe and efficient application; the role of action thresholds must also be re-considered. Rice is arguably the world’s most important crop by consumption: especially in SE Asia, where 618 million people (11.7%) currently live in 3.3% of the World’s land area. According to the Food and Agriculture Organisation (FAO) of the United Nations, it is the third most important crop in terms of agricultural commodity trade (after sugar and maize). Viêt Nam is currently the world’s fifth largest producer (after China, India, Bangladesh and Indonesia) but is usually one of the top two rice exporting countries. Threats to rice production include losses due to pests (insects, diseases, weeds and rodents). It has been estimated that losses due to pests in tropical Asia are approximately 37% – equivalent to 120–200 million tonnes.

In those days as now, the key insect pest was the brown plant-hopper (BPH), Nilaparvata lugens and diseases – rice blast, Magnaporthe grisea, especially in the spring crop and sheath blight, Rhizoctonia solani in the summer season. Methyl parathion and lindane were widely available insecticides, but effective controls of fungus diseases were in their infancy. The phenomenon of insecticide-induced resurgence of insects such as BPH was understood only by a few scientists in Vietnam, and had only been identified in the west for less than a decade. The roles of our team included providing for crop protection supplies (with specific instructions to ‘avoid toxic pesticides’, which I interpreted as no products in WHO class 1), carrying-out field trials to identify appropriate alternatives and encouraging the Government to adopt pesticide registration and quality control schemes. Crop protection activities were carried out on a commune basis, especially in the north and operationally, application with motorised mistblowers was considered most appropriate.

By the end of the 1980s, it had become widely understood that successful insect control was best achieved in the context of integrated pest management (IPM) and over the following decade this strategy, scientifically based on conserving NE (predators, parasitoids and pathogens: see below), became the general foundation for good agricultural practices in rice. In addition, farmers should: grow a healthy soil and crop; observe their field regularly (e.g. soil, water, plant, pests and natural enemies); and strive to become experts themselves.

This IPM strategy was enthusiastically officially adopted in Vietnam and other SE Asian countries, but I will argue here that real IPM is not is not being widely practiced by farmers for a number of reasons. Possibly the first of these has been a failure to appreciate the importance of, and engage with, pesticide companies, retailers and others whose business is pest management.

This is an abstract of the full article published in: Outlooks on Pest Management – April 2016 issue.

The full text of this article is available to subscribers of Outlooks on Pest Management.
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Author: Roy Bateman, Forest Floor Lodge, Cát Tiên National Park, ViêtNam.

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Category: Agriculture