IGRs are often mixed with other pesticides to

• A. Increase knock down
• B. Increase efficiency
• C. Increase residual control or persistence
• D. Increase odor

Answer: (C)

IGRs disrupt insect development and are slow-acting, so they’re often paired with fast-acting pesticides to provide longer-lasting control. An IGR prevents immature stages from maturing into adults or from reproducing, which reduces future pest populations. When mixed with a quick-killing product, you get immediate reduction in active pests plus extended suppression as new generations are prevented from maturing. That’s why increasing residual control or persistence is the best description. The other ideas—improving immediate knockdown, odor, or vague “efficiency”—don’t capture the main purpose of using IGRs in a mix, which is to extend the duration of control.