Which of the following is NOT a primary mode of pesticide action?

The primary modes of pesticide action refer to the primary ways that pesticides affect pests after they are applied. Contact, ingestion, and inhalation are all direct methods by which pesticides enter a pest's system and exert their effects, leading to mortality or control of the pest.

Contact action involves the pesticide coming into direct contact with the pest, either through the body surface or via exposure to treated surfaces. Ingestion occurs when the pest consumes the pesticide while feeding on treated plants or surfaces, leading to poisoning. Inhalation refers to the pesticide being absorbed through the respiratory system when a pest breathes in airborne particles.

Evaporation, on the other hand, is not considered a primary mode of pesticide action. While evaporation can occur with certain volatile compounds, it does not directly result in pest control through toxicity. Instead, evaporation pertains to the physical change of the pesticide from liquid to gas, affecting its application and effectiveness rather than its mode of action against pests. Therefore, this option stands out as the correct answer in the context of modes of pesticide action.