Floral Herbivory, Floral Phenology, Visitation Rate, and Fruit Set in Anaxagorea crassipetala (Annonaceae), a Lowland Rain Forest Tree of Costa Rica

Abstract

ARMSTRONG, J. E. (BEES Section, Campus Box 4120, Department of Biological Sciences, Illinois State University, Normal, IL 61790-4120) AND D. MARSH (Division of Environmental Studies, Wickson Hall, University of California, Davis CA 95616). Floral herbivory, floral phenology, visitation rate, and fruit set in Anaxagorea crassipetala (Annonaceae), a lowland rain forest tree of Costa Rica. J. Torrey Bot. Soc. 124: 228-235. 1997.-The flowering phenology, flower production, and insect visitation was determined for Anaxagorea crassipetala in a lowland rain forest study population containing fifty-two trees over 1.5 cm DBH. Flowering of each tree was monitored daily; 71% of the trees in the study population flowered producing a mean of 31.1 flowers/day. Flowers are cauliflorous, pendant, 2.4-2.7 cm long, with three prominant creamywhite, fleshy, outer petals, which represented 63% of floral biomass. Typical of cantharophily, flowers were protogynous, fruit-mimicking with a spicy, fruity fragrance. The perianth formed an enclosure, and rewards consisted of a protected location, stigmatic exudate, and petals capable of being used as a brood substrate. Anthesis commenced at first light, 05:05, lasting nearly 24 h. The receptive female phase preceeded the brief pollen-dispersing phase that began 0.5 h before the corolla and androecium shattered, ending anthesis. Four species of Coleopterans were floral visitors, 3 Nitidulidae and 1 Staphylimidae. Visitation rates peaked with population flowering, but decreased to zero after 33 days. A weevil (Cyrionyx sp.) was observed on buds and petals, and 1014 buds (43.7% of total) aborted, the result of a weevil larvae feeding in each bud. Fruit flies (Diptera: Drosophilidae) were frequently observed on buds and petals. At anthesis fruit fly larvae were feeding in 100% of outer petals, but no beetle larvae were found. None of the Coleopteran floral visitors carried a pollen load and none of the 1306 flowers was pollinated.