This protocol describes leaf-dip bioassay protocols to monitor the insecticide toxicity towards the insect pest (specifically for the sucking pest). The leaf-dip bioassay is usually used to measure the toxicity to for systemic Insecticides. In this bioassay, insects are exposed to technical grade/ formulated insecticide and responses (mortality) recorded at a specific post-exposure interval. The mortality data are subjected to log-dose probit analysis to generate estimates of a lethal concentration. These data collected over space and time could be used for monitoring insecticide resistance so as to develop appropriate insecticide resistance management strategies.