Nutritious tissue in petals of Annonaceae and its function in pollination by scarab beetles

Abstract

Th e feeding of pollinating dynastid-scarab beetles on nutritious tissue of Annonaceae fl owers results in macroscopically visible gnawing marks on petals. In the present paper, we present and discuss examples of such gnawing marks on Annonaceae from the Cerrado and the Amazon Forest in Brazil. Th e localization of gnawing marks on the petals and the histochemistry of the nutritious tissues are emphasized. In some species, nutritious tissue is apparently distributed among all petals, while in other species it is more or less diff usely localized. Th ere are also cases in which nutritious tissue occurs only on clearly localized regions of the inner petals. Petals of selected Amazon species were stained, and studied by light and scanning electron microscopy. Th e nutritious tissue consists of cells with mucilagerich walls, which contain starch, lipids and/or tannins. Starch and lipids are not only energy-rich food for the beetles but are apparently also "fuel" for metabolic heating of the fl owers, which is a further benefi t for the pollinators inside the pollination chamber.

Meiogyne oligocarpa (Annonaceae), a new species from Yunnan, China

“…They found polysaccharides on the strumae, suggesting that the structure may provide nutrition to floral visitors as well as a protected site for mating, oviposition, brooding and larval feeding (Shao & Xu, 2015). This is consistent with the ''food body'' hypothesis in Sapranthus (Schatz, 1987) or ''nutritious tissues'' hypothesis (Gottsberger & Webber, 2018). Moreover, Shao & Xu (2015) also introduced a third hypothesis, the ''brood-site'' hypothesis.…”

“…Shao & Xu (2015) studied the corrugations of Meiogyne hainanensis. Based on their observations, they raised two alternative hypotheses regarding the function of the inner petal corrugations, noting that polysaccharides may provide nutrition for floral visitors, and hence the corrugations may function as a ''food body '' as in Sapranthus (Schatz, 1987), aligned with the ''nutritious tissues'' hypothesis (Gottsberger & Webber, 2018).…”

Annotated catalog and bibliography of the cyclocephaline scarab beetles (Coleoptera, Scarabaeidae, Dynastinae, Cyclocephalini)

“… Olivier 1789 , Herbst 1790 , Burmeister 1847 , Harold 1869b , Arrow 1937b , Pike et al 1976 , Endrődi 1966 , 1967b , 1969b , 1985a , Dechambre 1991b , Ratcliffe 1992b , Webber and Gottsberger 1993 , Küchmeister et al 1998 , Gottsberger et al 1998 , Gottsberger 1999 , Silberbauer-Gottsberger 2001, Ponchel 2006 , 2011 , Krajcik 2005 , 2012 , Moore and Jameson 2013 , Costa et al 2017 .…”

(3S,6E)-nerolidol-mediated rendezvous of Cyclocephala paraguayensis beetles in bottle gourd flowers

“…The interaction of beetles and flowers may result in mutualistic pollination typically by the cantharophilous floral syndrome of basal angiosperms, whose flowers are usually bisexual, protogynous, very scented, and thermogenic [4,5]. The Cyclocephalini beetles are primarily attracted by strong odors released by flowers as chemical cues to indicate a rendezvous site for food, shelter, and mating sites [4,6,7].…”