Heterogeneous ecosystems have been known to interfere with host finding abilities of insect pests. Intercropped food crops also model heterogeneous ecosystems to influence insect population dynamics in a similar fashion. Intercropping has been widely used in Integrated Pest Management (IPM) to reduce pest damage. This study, sought to verify the effect of mint intercrops on insect abundance and plant performance among collards. The mode by which the mints influence insect abundance and plant performance is identified. The mechanism by which such effects are achieved is, however, not clear from the study. First, collard greens (Brassica oleracea var. acephala) were intercropped with three species of mints (Mentha arvensis, M. piperita and M. spicata) as well as a ‘neutral plant’ (Verbena urticifolia). Secondly, mint extracts were sprayed on monocrops at regular intervals throughout the growing season. Collard performance was then assessed by plant biomass, leaf petiole diameter, and percent leaf area removed by insect herbivory. Insect abundance was monitored by using sticky cards and vacuum suction samples. Results indicate that mints have significant beneficial effects on both plant performance and insect abundance. The effect of extract sprays point to mint phytochemistry as the mode of action. Among the three mint species, M. spicata was less effective at suppressing insect abundance and enhancing collard performance. Physical intercrops were, however, more effective than the extract sprays. The presence of mints enhanced collard performance and generally suppressed arthropod abundance among the eleven insect taxa observed.

Key words: Brassica oleracea, insect abundance, intercropping, Mentha spp., plant performance.