Ecology, 86(4), 2005, pp. 905913
2005 by the Ecological Society of America
COMMUNITY CONTEXT OF AN OBLIGATE MUTUALISM: POLLINATOR
AND FLORIVORE EFFECTS ON YUCCA FILAMENTOSA
DAVID M. ALTHOFF,1
KARI A. SEGRAVES, AND OLLE PELLMYR
Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844-3051 USA
Abstract. Obligate pollination mutualisms have been central to our understanding of
the ecology and evolution of mutualisms. Although usually viewed as pairwise interactions,
obligate mutualists also interact with other community members that may impact the mu-
tualism. In this study, we examined the community context of the obligate mutualism
between the plant Yucca filamentosa and its yucca moth pollinator Tegeticula cassandra
to determine the relationships among plant traits, the community assemblage, and fruit set.
In addition to attracting its pollinator, Y. filamentosa in central Florida also attracts two
insect florivores: the hemipteran Leptoglossus phyllopus and the beetle Hymenorus densus.
We surveyed flowering Y. filamentosa in 2001 and 2002 to determine the abundance of the
three insect species throughout the flowering period. We also measured fruit set and four
plant traits thought to be important in attracting the moth pollinator. Path analysis revealed
that T. cassandra was the most important determinant of relative fruit set for both years.