Unpredictable seed-set: a defence mechanism against seed-eating insects inProtea species (Proteaceae).

Extent of pre-dispersal seed destruction by insects and seed survival were measured for variousProtea species (Proteaceae) and related to seed-set, variation in seed-set, the percentage of barren infructescences and infructescence age. The hypothesis that low and variable seed-set would act as a defence mechanism against insect seed predators was tested. Results indicated that seed survival and variation in seed-set were highly positively correlated, while seed survival and seed-set were negatively correlated. Variation in seed-set was identified as the most important determinant of seed survival for the range ofProtea species studied.