The Pollination Biology of Tuckahoe, Peltandra virginica (Araceae)

Abstract

This study describes the specialized brood-site-based pollination system of Peltandra virginica Kunth (Araceae) with the chloropid fly Elachiptera formosa Loew and provides experimental evidence that gender-related changes in floral odor composition synchronize pollinator behavior with the blooming sequence. P. virginica is protogynous and does not selfpollinate because ofa strong temporal separation in sexual function, and it is dependent upon insects for pollination because the spathe completely surrounds the spadix during the pistillate stage. Field observations conducted in central New Jersey and southeastern Pennsylvania showed that E. formosa is closely associated with P. virginica inflorescences. Within the floral chamber, Ei formosa adults feed on pollen, mate, and find oviposition sites while the larvae complete their development. Although drosophilid and syrphid flies were collected and reared from inflorescences of both sexual stages, only E. formosa emerged from pistillate-stage inflorescences and adult E. formosa rapidly transferred fluorescent dye particles between inflorescences of both sexual stages in laboratory enclosures. These findings indicate that this fly species is the primary pollinator at our study locations. Field censuses demonstrated that although E. formosa visited P. virginica inflorescences of both sexual stages with equal frequency, the female flies preferentially oviposited within pistillate-stage inflorescences. Analysis offloral volatiles with gas chromatography-mass spectrometry showed that only the spathes emit the floral fragrance and that the composition of the floral volatiles changed during the transition from pistillate to staminate stage. A particularly noticeable change occurred in the emission ratio of the two primary floral odor components, 4,5,7-trimethyl-6,8-dioxabicyclo[3.2.1.]octane and an unidentified chemical analog with molecular weight of 142. The relationship between floral volatile composition and fly oviposition behavior was evaluated using sham inflorescences placed in the P. virginica study population. The sham inflorescences were constructed by covering spadices dissected from mature inflorescence buds with spathes excised from different-age inflorescences. After a 2-hr-Iong exposure period, sham inflorescences fitted with pistillate-stage spathes contained more E. formosa eggs than the sham inflorescences with staminate-stage spathes. However, the highest number of ovipositions occurred in sham inflorescences fitted with spathes excised from mature inflorescence buds. The fragrance emitted by these spathes was composed almost entirely of the two principal odor components. The decline in ovipositions observed in both real and sham inflorescences corresponded to an increase in the emission ratio of 4,5,7trimethyl-6,8-dioxabicyclo[3.2.I.]octane to the molecular weight 142 analog. This suggests that gravid flies searching for oviposition sites used the ratio of the two primary floral volatile components as an inflorescence gender or age recognition cue. I ...

A new pollinating seed‐consuming mutualism between Rheum nobile and a fly fungus gnat, Bradysia sp., involving pollinator attraction by a specific floral compound

“…Floral scent production is a dynamic process and changes are considered to be adaptive with respect to pollinator behaviour (Patt et al, 1995). In our study, we found the overall scent profiles of R. nobile at anthesis to be significantly different from those at either preanthesis or postanthesis (Fig.…”

Review: Ecological networks – beyond food webs

“…It has been remarked for instance that headwater stream FWs bear some striking similarities to soil food webs, yet both differ profoundly from many HPWs (Woodward et al 2005b). Many aquatic plants also require animal pollination (Haynes 1988;Harder & Barrett 1992;Patt et al 1995;Lippok & Renner 1997), so are aquatic and terrestrial MWs comparable -and indeed interconnected?…”

Floral diversity and pollination strategies of three rheophytic Schismatoglottideae (Araceae)

“…So far, the role of floral fragrance in mediating plant-insect interactions has only been investigated in a few species scattered across the Araceae (i.e. Patt et al 1995;Hadacek & Weber 2002;Kumano-Nomura & Yamaoka 2009;Maia et al 2010Maia et al , 2012Maia et al , 2013D€ otterl et al 2012). Hadacek & Weber (2002) reported a gradient in odour emissions in the inflorescence of Sauromatum guttatum Schott, ranging from foul-smelling in the appendix to a pleasant flowery odour at the interstice club-shaped sterile organs, and these odour compounds attracted a wide range of insects into the floral chamber.…”