Seed losses In fruits on trees ofEucalyptus delegatensis

Summary Ten fruits were collected at random from each of five parent trees of Eucalyptus delegatensis R.T.Bak. (alpine ash) in each of 18 separate localities in New South Wales and the Australian Capital Territory in 1977. The contents (both seed and chaff) were carefully extracted and the seed examined for insect damage. Seeds destroyed by insects were common. In some individual-tree samples the fraction of seeds destroyed was as high as 81% but the overall mean for all tree samples examined was 20%. Significant differences in the fraction of seeds destroyed were found among localities, and one region, enclosing 3 adjacent localities, had significantly higher numbers of seeds destroyed per fruit than the remaining localities. Two unidentified species of Megastigmus spp. (Hymenoptera: Torymidae) were most commonly associated with seed destruction within fruits.