Insect Seed Predators May Cause Far Greater Losses Than They Appear to

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Abstract
Pre-dispersal seed losses to insects are conventionally measured by inspecting mature fruits and seeds for signs of insect attack. Using this technique I estimated that losses in Eucalyptus baxteri, Leptospermum myrsinoides, L. juniperinum and Casuarina pusilla were 2%, 10%, 28% and less than 1%, respectively. However insect exclusion experiments, which themselves gave conservative results, indicated that actual losses were 66%, 64%, 44%, and 83%, respectively. The experiments suggested that insects had two important effects on seed production that could not be determined by assessing mature fruits and seeds: they reduced total numbers of seeds per fruit, and they caused large reductions in seed viability. The reliability of conventional methods of assessing pre-dispersal seed losses to insects must therefore be seriously questioned.