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Inflorescence Damage by Insects and Fungi in Native Pili Grass (Heteropogon contortus) versus Alien Fountain Grass (Pennisetum setaceum) in Hawai'i
|Title:||Inflorescence Damage by Insects and Fungi in Native Pili Grass (Heteropogon contortus) versus Alien Fountain Grass (Pennisetum setaceum) in Hawai'i|
Daehler, Curtis C.
|Issue Date:||Apr 2001|
|Publisher:||University of Hawai'i Press|
|Citation:||Goergen E, Daehler CC. 2001. Inflorescence damage by insects and fungi in native pili grass (Heteropogon contortus) versus alien fountain grass (Pennisetum setaceum) in Hawai'i. Pac Sci 55(2): 129-136.|
|Abstract:||The success of introduced invaders has often been attributed to their
release from natural enemies, We compared rates of seed and ovule destruction
by insects and fungal pathogens in an alien invader, fountain grass (Pennisetum
setaceum), and a declining native competitor, pili grass (Heteropogon contortus), to
determine whether the invader experienced less damage from natural enemies.
Inflorescences were sampled on O'ahu from three sites on three dates, and seeds
and ovules were inspected for insect damage or pathogen infection. Total seed
and ovule destruction was significantly lower in alien fountain grass at all times
and sites, with the exception of one sample date on Ka'iwa Ridge when very
little damage « 1%) was observed in either species. Total seed and ovule destruction
ranged from 0.8 to 5% in fountain grass versus 0 to 61% in pili grass.
Most seed and ovule loss in pili grass was caused by infection with the smut
fungus Sporisorium caledonicum. Between 5 and 35% of pili grass inflorescences
showed signs of smut infection. No fungal pathogens were noted on fountain
grass. The low impact of natural enemies on seed production in alien fountain
grass, relative to native pili grass, could confer a long-term reproductive advantage
to the alien.
|Appears in Collections:||Pacific Science Volume 55, Number 2, 2001|
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