Chapter 21

Integrated Pest Management for Greenhouse Crops

Biorational Pest Control Tactics

Pest control materials that are relatively non-toxic to people with few environmental side effects are sometimes called “biorational” pesticides. Biorational pesticides vary in their toxicity and in their potential ecological impact. Biorationals in general have a narrow target range and a very specific mode of action. They are slow acting, have a relatively critical application times, suppress, rather than eliminate a pest population. In addition, they have limited field persistence and a shorter shelf life than conventional synthetic pesticides and present no residue problems. Biorationals fit well into an integrated pest management strategy, which relies on monitoring for early detection of pests and emphasizes the use of selective products that provide control while preserving the ecological health of the farm and minimizing negative effects on beneficial insects that suppress pests. Biorationals encompass a broad array of pesticides which can be classified as follows: 1) microbials, 2) botanicals, 3) spray oils, 4) insecticidal soaps, 5) minerals, and 6) pheromones. A similar term that is used by EPA is “biopesticides” (defined in the following section) and often used interchangeably with the term biorationals.


Biopesticides, as defined by the Environmental Protection Agency (EPA), are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. Categories of biopesticides include: 1) biochemical pesticides, which are naturally occurring substances that control pests by non-toxic mechanisms, such as sex pheromones that interfere with mating and scented plant extracts that attract insect pests to traps; 2) microbial pesticides, which consist of a microorganism (e.g., a bacterium, fungus, virus or protozoan) as the active ingredient; and 3) Plant-Incorporated-Protectants (PIPs), in which pesticidal substances are produced by crop plants as a result of genetic material being added to the plant (e.g., Bt insecticidal protein). With plant-incorporated protectants, the toxin and its genetic material, but not the plant itself, are regulated by EPA.

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