To sustainably manage the maize stem borer (Busseola fusca) and improve crop yields without synthetic chemical inputs, farmers in sub-Saharan Africa employ a companion cropping strategy. They intercrop maize with silverleaf desmodium (Desmodium uncinatum), which emits volatile organic compounds that repel the adult moths. Around the perimeter of the field, they plant Napier grass (Pennisetum purpureum), which releases attractive cues that entice the moths to lay eggs on it rather than the maize, while producing a sticky sap that restricts larval survival.
What is the correct name for this agricultural strategy, and what ecological roles do Desmodium and Napier grass play, respectively?
Push-pull system; Desmodium acts as the 'push' (repellent) and Napier grass acts as the 'pull' (trap crop).
Push-pull system; Desmodium acts as the 'pull' (attractant) and Napier grass acts as the 'push' (repellent).
Allelopathic control; Desmodium acts as a soil biofumigant and Napier grass acts as a physical barrier crop.
Biological pest control; Desmodium acts as a parasitoid nursery and Napier grass acts as a predatory vector.