Rice in Vietnam is grown under intensive cultivation conditions to maximize production. Farmers usually grow two crops a year and in some cases three crops in large continuous areas, applying high levels of chemical fertilizers and pesticides. Pests are often considered to be major constraints to yields and the farmers’ main control tactic is spraying pesticides. Because of poor spray equipment and poor knowledge, a large proportion of farmers’ sprays are misused (Heong & Escalada, 1997; Bandong et al., 2002). Farmers tend to focus on highly visible leaf damage like that caused by the leaf-feeding caterpillars in the early crop stages. However, this damage has little effect on yields because of plant compensation (Graf et al., 1992). These early season sprays instead destroy biodiversity and biological control ecosystem services and make the rice more vulnerable to more destructive secondary pests such as planthoppers (Way & Heong, 1994; Heong & Schoenly, 1998; Heong, 2009). Believing that rice pests breed in neighboring habitats, farmers also tend to spray these habitats with pesticides. However, the most important rice pests are monophagous and thus such practices are of no use, and do more harm by destroying the rich biodiversity of resident predators and parasitoids.
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