Deltamethrin is a broad-spectrum insecticide used in agriculture (crop protection), public health (mosquito and malaria control), and veterinary applications (ectoparasiticide). For agricultural use, ensure the formulation has strong UV stability and rain-fastness to maintain residual activity. For public health, particularly Indoor Residual Spraying (IRS) or Long-Lasting Insecticidal Nets (LLINs), the product must meet strict WHOPQ (WHO Prequalification) standards to ensure safety for human contact.