How can trap crops and border crops reduce pests organically?

A trap crop is a plant that pests prefer more than your main crop, so you sow it to pull the pest away, then deal with the pest concentrated there. Common examples are marigold planted with tomato to draw fruit borer and some nematodes, castor or African tall marigold around cotton or vegetables to attract Spodoptera and Helicoverpa egg laying, and mustard or maize as border rows to pull aphids and shelter natural enemies. The idea is the pest lays eggs or gathers on the trap crop, and you then destroy those plants or spot treat only that strip, sparing the main crop and the helpful insects. Border crops of tall plants like maize or jowar around a field also act as a barrier and host predators. These cultural methods are cheap, preventive and fit naturally with bird perches and traps. The honest point is you must monitor the trap crop and actually destroy or treat the pest gathered there, otherwise it just becomes a breeding ground that makes things worse. Ask your KVK for the right trap crop and ratio for your main crop.