Remedial Control Action Required

TIME ->

pest species.

on other organisms in the environment are treated as costs in addition to monetary costs associated with insecticide application. Quantifying environmental costs has proven to be challenging and subject to much debate, but progress under this refined concept of EIL nonetheless has been made.

In 1984 W. L. Sterling advanced the concept of "inaction level," which is the density of natural enemies sufficient to maintain a pest below the EIL. M. P. Hoffmann and collaborators developed a sampling program for eggs of tomato fruitworm, Helicoverpa zea, that permits ready identification and quantification of parasitized eggs in addition to healthy eggs. If the level of egg parasitism is determined to be too low to prevent larval numbers from exceeding the EIL, the lowest adequate rate of a "soft" pesticide (one having least impact on parasitoids and other nontarget organisms) is recommended. This approach is an example of application of the inaction level concept and represents a high degree of first-level IPM implementation.

Area-wide IPM is an expansion of first-level IPM that may represent a significant transitional step toward second and third levels of IPM. Under area-wide IPM, the key pest of a crop is targeted for management by means of the most effective noninsecticidal approach. For example, the codling moth, Cydia pomonella, is managed in apple and pear orchards by tactics such as the pheromone mating disruption technique or the sterile insect release method, that impair normal reproduction. Such tactics are implemented over areas large enough to preclude recolonization by fertile females from adjacent areas. By reducing the impact of broad-spectrum insecticides, natural enemies are preserved and are usually capable of regulating most secondary pests in the crop. As area-wide IPM programs expand to incorporate multiple pest interactions, they become natural springboards to higher level integration in IPM systems.

0 0

Post a comment