Mast seeding ofChionochloa(Poaceae) and pre-dispersal seed predation by a specialist fly (Diplotoxa, Diptera: Chloropidae)

摘要

Levels of seed predation were recorded between 1986 and 1992 inChionochloa pattens, C. oreophila, C. flavescens, C. macra, andC. crassiusculapopulations at various altitudes at three sites in Canterbury. There were consistently high levels of attack by a chloropid fly,Diplotoxa similis: between 22 and 94 of florets showed evidence of fly damage, except at higher altitudes (decreasing to 2 inC. pattensat 1620 m) and inC. oreophila(6 – 10). Since D.similisemerges rapidly from the pupa and since larvae possibly move between florets, the number of insects found underestimated the number of florets predated by up to 90. Seed set varied from 2 to 59 and was negatively correlated with seed predation.