Pollination by ants has been reported so far for 18 monocot and dicot families and about 36 plant species, with 57 species from 5 subfamilies of ants described as pollinators (see Table A1 for details). These figures keep increasing as more information accumulates. Species of herbs, treelets, trees, shrubs, epiphytic, saprophytic and parasitic plants worldwide have been described to be ant-pollinated. Some of them live

in habitats where ant frequency is high, and show features included in the “ant-pollination syndrome”: short plants, and sessile and small flowers with nectar as the main Crizotinib in vitro reward (Hickman, 1974). In other cases, a correspondence between flower traits and ant pollination is not evident, but ants have nevertheless been proved to be effective pollinators (Peakall et al., 1987, Peakall, 1994, Ramsey, 1995 and Sugiura et al., 2006). Chemical communication between ants and plants is crucial for the establishment and avoidance of interactions, and plant volatile organic compounds (VOCs) are key elements in these processes. Vegetative volatiles released by myrmecophytic plants are decisive in attracting their obligate ant symbionts that help protect plants against herbivores (Agrawal, 1998, Brouat et al., 2000, Edwards et al., 2006 and Inui and Itioka, 2007), and volatiles from seeds are crucial for the establishment of ant–gardens in obligate mutualisms between ants and epiphytes (Youngsteadt et al., 2008). In line

with the prevailing detrimental role attributed to ants when they interact with flowers, floral volatiles have been shown to act as repellent allomones http://www.selleckchem.com/products/AZD2281(Olaparib).html (Willmer and Stone, 1997, Junker and Blüthgen, 2008, Willmer et al., 2009 and Junker et al., 2011b). Nevertheless, whether volatiles play some role in mutualistic ant–flower interactions, functioning as synomones that promote effective pollination, still remains largely unexplored (but see Schiestl and Glaser, 2012). Floral Unoprostone scent is an important component of floral phenotype and represents

a decisive communication channel between plants and animals. It facilitates attraction of pollinators (Raguso, 2008) and promotes pollinator specificity by the intensity of the signal, the presence of unique VOCs, and exclusive multicomponent blends of ubiquitous compounds (Ayasse, 2006, Dobson, 2006, Raguso, 2008, Schiestl, 2010, Schiestl and Dötterl, 2012 and Farré-Armengol et al., 2013). The specificity of floral VOCs in attracting specific guilds of pollinators including moths, flies, bees, wasps, beetles, bats, or even rodents has been previously studied (Dobson, 2006, Knudsen et al., 2006, Raguso, 2008, Peakall et al., 2010, Johnson et al., 2011 and Maia et al., 2012), but the chemical composition and function of the floral scent of species pollinated by ants remains virtually unexplored. Since chemical signals are essential sources of information to ants (Hölldobler, 1999, Lenoir et al., 2001, Martin et al.