Ecological relationship between floral thermogenesis and pollination in Nelumbo lutea (Nelumbonaceae).
OBJECTIVE
Floral thermogenesis is an unusual floral trait with a well-documented physiological process, and yet, there is limited understanding of how this trait influences plant reproduction. The current study was undertaken to gain a better understanding of how floral thermogenesis in Nelumbo lutea impacts pollinator attraction and consequent plant reproduction.


METHODS
We conducted field studies on floral thermogenesis and thermoregulation, flower sexual development, floral visitation patterns, breeding system, pollen transfer dynamics, and floral scent production.


RESULTS
The most abundant visitors to the thermoregulatory flowers included the Phoridae (Diptera), Chrysomelidae (Coleoptera), and Hymenoptera. Chrysomelid beetles, particularly Diabrotica, were frequent visitors to both first-day female- and second-day bisexual-phase flowers, while phorid flies were most common in bisexual-phase flowers. Pollen transfer experiments indicated that Diabrotica was equally effective in depositing pollen on stigmas, as were the less frequent, but pollen-loaded halictid bees.


CONCLUSIONS
Flowers received a taxonomically wide assemblage of floral visitors and appear adapted to attract beetles, primarily Chrysomelidae and medium-sized bees. This study is the first to provide strong support that beetles can comprise the dominant portion of floral visitors and are as effective in pollen transfer as bees. Thermogenesis aids in dispersing the main floral scent component-1,4-dimethoxybenzene-attracting both chrysomelids and bees, while thermoregulation causes chrysomelid beetles to actively seek out new flowers for evening residence. This search behavior likely results in chrysomelids affecting cross-pollination.
Department of Natural Sciences, Northwest Missouri State University, 800 University Dr., Maryville, Missouri 64468.
Gregg
G
Dieringer
R
R
Leticia Cabrera
Mohammad
M
Mottaleb
D000220:Adaptation, Biological; D000818:Animals; D000840:Anisoles / Q000378:metabolism; D001517:Coleoptera; D004175:Diptera; D004463:Ecology; D035264:Flowers / Q000378:metabolism / Q000502:physiology*; D006927:Hymenoptera; D031653:Nelumbo / Q000502:physiology*; D009812:Odorants; D011058:Pollen; D054817:Pollination; D012098:Reproduction; D022722:Thermogenesis
D000840:Anisoles; C031200:1,4-dimethoxybenzene
Chrysomelidae; Halictidae; Nelumbo lutea; Nelumbonaceae; Phoridae; beetle pollination; thermogenesis; thermoregulation