干旱区生态环境知识资源中心

In the ’Integrated Control Concept’, Stern et al. emphasized that, although insecticides are necessary for agricultural production, they should only be used as a last resort and as a complement to biological control. They argued that selective insecticide use should only be attempted after it has been determined that insect control with naturally occurring biotic agents is not capable of preventing economic damage. However, they concluded their seminal paper by emphasizing that integrated control will not work where natural enemies are inadequate or where economic thresholds are too low to rely on biological control. Thus, it is no surprise that insect control in high-value, fresh-market lettuce crops grown in the desert southwest have relied almost exclusively on insecticides to control a complex of mobile, polyphagous pests. Because lettuce and leafy greens are short-season annual crops with little or no tolerance for insect damage or contamination, biological control is generally considered unacceptable. High expectations from consumers for aesthetically appealing produce free of pesticide residues further forces vegetable growers to use chemical control tactics that are not only effective but safe. Consequently, scientists have been developing integrated pest management (IPM) programs for lettuce that are aimed at reducing the economic, occupational and dietary risks associated with chemical controls of the past. Most of these programs have drawn upon the integrated control concept and promote the importance of understanding the agroecosystem, and the need to sample for pest status and use action thresholds for cost-effective insect control. More recently, pest management programs have implemented newly developed, reduced-risk chemistries that are selectively efficacious against key pests. This paper discusses the influence that the integrated control concept, relative to zero-tolerance market standards and other constraints, has had on the adoption of pest management in desert lettuce crops. (C) 2009 Society of Chemical Industry