Wednesday, August 8, 2007 - 10:10 AM

COS 69-7: Early folivory can magnify the impact of late frugivory

T'ai H. Roulston, University of Virginia

Folivores, florivores, frugivores, and pollinators can influence plant reproduction in different and independent ways. Recent work has shown that some antagonists may reduce plant reproduction not only through direct loss of tissues but also by making flowers or plants less attractive to pollinators. It is also possible for antagonists to interact, even when greatly separated in time, such that damage induced by one antagonist can increase the absolute or relative damage of another antagonist in various ways. I studied the interaction between antagonists of Physalis longifolia ssp. subglabrata in Virginia during the summer of 2006. The specialist folivore Lema tridentata (Chrysomelidae) occurred on 50 of 96 plants during the first 3 weeks of the flowering season, completely defoliating 11 plants. Although all plants resprouted and produced abundant flowers, these new flowers went to fruit at the time when frugivory by the specialist frugivore Heliothis subflexa reached its peak. An experiment demonstrated that Heliothis subflexa prefers young fruits, which made all fruits produced after repsrouting more susceptible to frugivory than old fruits retained by non-defoliated plants. Thus, the impact of frugivory in the system was magnified by the phenological shift in flower production imposed by folivory. This effect was further magnified by the finding that early fruits contained more seeds than later fruits. 

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