Control in IPM Systems
David A. Andow
Integrated pest management (IPM) as originally conceived was a methodology for integrating chemical and biological control ( Stern et al. 1959). In its more practical incarnation, however, IPM was developed mainly as a means to optimize the use of chemical insecticides based on information about pest incidence. Natural control can be readily incorporated into this framework, and at least two contrasting approaches have been proposed. Ostlie and Pedigo ( 1987) propose using historical data on pest mortality to discount observed pest incidence data used to calculate the expected gain from chemical application. Because actual natural control will vary around the historical average, they suggest using a number that is lower than the mean historical value in discounting pest incidence. Nakasuji et al. ( 1973) propose using real-time estimates of natural control to discount observed pest incidence data. They suggest that natural enemy incidence data be collected concurrent with pest incidence data. Real-time estimates of natural control can be projected from a mechanistic understanding of the natural enemy-host pest relationship. Development and implementation of either idea in IPM has been slow.
For the past two decades there have been increasing calls to integrate biological control and IPM. Much of this has been aimed at incorporating inundative releases of natural enemies and methods to conserve natural enemies into contemporary pest management systems. Biological control of European corn borer in corn using inundative releases of Trichogramma brassicae has been implemented successfully in parts of Europe ( Raynaud and Crouzet 1985; Bigler and Brunetti 1986; Hassan et al. 1986), and use of T. dendrolimi in control of Asian corn borer is common in China ( Zhang 1986). Despite these successes, Trichogramma is used only sparingly in the United States against European corn borer. Several operational and biological factors constrain the use of Trichogramma against corn borer in the United States, and in this chapter I will discuss them from the IPM perspective, and provide an analysis of the technical constraints to their increased use.