ABSTRACT
Intercrop diversity or polycultures can result in higher crop yields for a number of reasons of which one clearly demonstrated advantage is that insect pest populations are greatly reduced. Ecological hypotheses suggest two ways that can explain pest reduction in polycultures, 1) from a greater number of predators and parasites and 2) by disruption of the pests’ movement and reproductive behaviour, the visual and chemical stimuli from host and non-host plants affect both the rate at which insects colonise habitats and their behaviour in those habitats. Examples are presented from experiments with annual crops to demonstrate ways of studying the ecological mechanisms causing pest suppression by intercropping.
