Armstrong, Joseph E. , Collier, Glen E. .
Florivory and pollination of Anaxagorea crassipetala, a neotropical species of Annonaceae.
Like flowers of other Annonaceae, the perianth of Anaxagorea crassipetala consists of 3 whorls of 3 tepals. Tepals of the middle whorl are thick and fleshy constituting 64% of the floral biomass. In a family pollinated almost exclusively by beetles, these fleshy tetals were expected to serve as a brood substrate for beetle mutualists. Beetles are the only organisms observed to enter the perianth and interact with the sporophylls in such a way as to effect pollination. During three seasons of field futility, only 13 monitored flowers have set fruit. Two insect florivores compete for this tepal biomass. 40-47% of the flower buds abort before anthesis, an event caused by the feeding of a single weevil larvae (Curculionidae: Baridinae: Cyrionyx sp.) in each bud. Flowers surviving to anthesis are found on average to have 12.5-13.9 dipteran larvae (Drosophilidae: Diathoneura tesselata) in 77.5% of their fleshy tepals (n = 610 flowers). The dipteran larvae consist of two broods, a small one resulting from ovipositions prior to anthesis, and a second larger brood resulting from ovipositions on the day of anthesis. While fewer in number the pre-anthesis ovipositions result in larger offspring. While this latter set of flowers reaches anthesis, results of a bagging experiment suggest pollination is more successful if no other insect larvae are feeding in the tepals. These observations suggest that florivory can exert a profound negative effect on pollination. However, the reproductive success of beetle pollinators remained unchanged; it was zero. No Coleopteran larvae have ever been found in these tepals. Is this an artifact of sampling, a snapshot in ecological time? Is this flower maladaptive? Do we misjudge what is a successful rate of reproduction?
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1 - Illinois State University, Department of Biological Sciences, Campus Box 4120, Normal, Illinois, 61790-4120, USA
2 - University of Tulsa, Department of Biological Sciences, 600 South College Ave., Tulsa, OK, 74104
Presentation Type: Oral Paper:Papers for Sections
Location: Council Chambers/SUB
Date: Monday, July 28th, 2008
Time: 1:45 PM