Final answer:
IGRs are added to insecticides to enhance their efficiency, provide faster control, and aid in resistance management, hence reducing insect populations and associated costs in a sustainable way.
Step-by-step explanation:
Insect Growth Regulators (IGRs) are added to insecticides to increase efficiency, enable faster control, and to ensure long-term insect resistance management. They act by disrupting the normal development of insects, which can lead to decreased populations over time without the need for immediate knockdown.
IGRs help in controlling insect populations, managing resistance, and reducing costs, making them a valuable tool in integrated pest management (IPM).