Hawkmoth Pollinators Decrease Seed Set of a Low-Nectar Petunia axillaris Line through Reduced Probing Time

Institute of Biology, University of Neuchâtel, Emile Argand 13, 2009 Neuchâtel, Switzerland.
Current biology: CB (Impact Factor: 9.92). 07/2012; 22(17):1635-9. DOI: 10.1016/j.cub.2012.06.058
Source: PubMed

ABSTRACT Although deception of floral pollinators is well known among orchids [1, 2], the majority of animal-pollinated plants secure pollination by nectar rewards. The costs and benefits of nectar production remain poorly understood [3-5]. Here, we developed a crossing design to introgress a low-nectar-volume locus of Petunia integrifolia into the genetic background of P. axillaris. The resulting introgression line resembled P. axillaris but produced only one-third of the nectar volume. When exposed simultaneously to low-nectar and wild-type P. axillaris plants, hawkmoth pollinators reduced their probing duration on low-nectar plants but otherwise did not show any signs of discrimination against these plants. However, reduced probing duration resulted in reduced seed production in the low-nectar plants despite their higher reproductive potential as evidenced by hand pollination. In line with this interpretation, we found a positive correlation between probing duration and seed set, and hawkmoth pollination of low-nectar plants that were manually supplemented with nectar to parental levels yielded seed sets similar to hand pollination. Thus, a simple self-serving pollinator behavior-the adjustment of probing time in response to nectar volume-may select against reducing nectar and protect many plant-pollinator mutualisms against a drift toward parasitism. VIDEO ABSTRACT:

  • Source
    • "Nectar plays multiple roles in plant pollination (floral nectar, FN) and in the indirect defence of plants against herbivores (extrafloral nectar, EFN) (Heil, 2008, 2011; Brandenburg et al., 2009). In addition to its chemical composition , the quantity of nectar secreted also represents an important trait that is positively correlated with pollination success or the resulting indirect defence (Heil et al., 2009; Brandenburg et al., 2012). Plants are therefore capable of adjusting nectar secretion rates to the current needs, and may even re-absorb unconsumed nectar (Pederson et al., 1958; Ziegler and Lü ttge, 1959; Bú rquez and Corbet, 1991; Nicolson, 1995; Heil et al., 2000; Nepi et al., 2001, 2011b; Escalante-Perez et al., 2012). "
    [Show abstract] [Hide abstract]
    ABSTRACT: In spite of the ecological and evolutionary importance of nectar, mechanisms controlling its synthesis and secretion remain largely unknown. It is widely believed that nectar is 'secreted phloem sap', but current research reveals a biochemical complexity that is unlikely to stem directly from the phloem. We used the short daily peak in the production of extrafloral nectar by Acacia cornigera to investigate metabolic and proteomic dynamics before, during and after the 2 hours of diurnal secretion. Neither hexoses nor dominating nectar proteins (nectarins) were detected in the phloem before or during nectar secretion, excluding the phloem as the direct source of major nectar components. Enzymes involved in the anabolism of sugars, amino acids and proteins, and nectarins such as invertase, β-1,3-glucanase and thaumatin-like protein, accumulated in the nectary directly before and diminished quantitatively after the daily secretion process. Corresponding genes were expressed almost exclusively in nectaries. By contrast, protein catabolic enzymes were mainly present and active after the secretion peak and might function in the termination of the secretion process. The metabolic machinery for extrafloral nectar production is synthesized and active during concurrent secretion and is degraded thereafter. Knowing the key enzymes involved and the spatiotemporal patterns in their expression will allow the elucidation of mechanisms by which plants control nectar quality and quantity. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.
    The Plant Journal 10/2013; 73(4):546–554. DOI:10.1111/tpj.12052 · 6.82 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nectar is the major currency bringing together plants and pollinators; yet the costs and benefits of nectar production remain poorly understood. A low nectar line developed in Petunia offers an innovative approach to this problem and may offer clues to why some plants cheat and secure pollination via deception.
    Current biology: CB 09/2012; 22(17):R680-2. DOI:10.1016/j.cub.2012.06.072 · 9.92 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In many instances of cooperation, only one individual has both the potential and the incentive to 'cheat' and exploit its partner. Under these asymmetric conditions, a simple model predicts that variation in the temptation to cheat and in the potential victim's capacity for partner control leads to shifts between exploitation and cooperation. Here, we show that the threat of early termination of an interaction was sufficient to induce cleaner wrasse Labroides dimidiatus to feed selectively against their preference (which corresponds to cooperatively eating client fish ectoparasites), provided that their preference for alternative food was weak. Under opposite conditions, cleaners fed selectively according to their own preference (which corresponds to cheating by eating client mucus). By contrast, a non-cleaning fish species, Halichoeres melanurus, failed to adjust its foraging behaviour under these same conditions. Thus, cleaners appear to have evolved the power to strategically adjust their levels of cooperation according to the circumstances.
    Proceedings of the Royal Society B: Biological Sciences 04/2013; 280(1761):20130553. DOI:10.1098/rspb.2013.0553 · 5.29 Impact Factor
Show more