Generalist flowers are visited by a broad variety of insects that function as pollinators, occasional visitors and as pollen and/or nectar robbers. Moreover, among legitimate pollinators the pollination efficiency can be different. Nectar greatly affects visitor behaviour and fidelity to a certain species, influencing plant reproductive effort. In this study we have investigated a generalist system (Gentiana lutea L.), examining the role of flower visitors and quantifying the contribution of each pollinating taxon in three natural populations. In order to verify the level of generalization, we introduce an index of Pollinator Performance (PoP), based on insect visitation rate and cross-pollen transport efficiency. Our results confirm the high degree of pollinator-generalization of the study species. Nevertheless, flower visitors show various degree of pollinating performance, mainly defined by their sedentary versus dynamic behaviour. Sedentary insects enhance geitonogamous pollen transfer, which results in reduced seed set and pollen limitation. In particular, an unusual sluggish behaviour was observed in bumblebees feeding on nectar. The hexose-rich abundant nectar offered by G. lutea flowers is remarkably rich in proline and β-alanine amino acids: this composition presumably influences feeding choice and insect dynamism, likely exerting a narcotic effect on pollinators. The consequences on plant fitness are discussed in an evolutionary perspective.

Bouncy versus idles: on the different role of pollinators in the generalist Gentiana lutea L.

FISOGNI, ALESSANDRO;GALLONI, MARTA
2014

Abstract

Generalist flowers are visited by a broad variety of insects that function as pollinators, occasional visitors and as pollen and/or nectar robbers. Moreover, among legitimate pollinators the pollination efficiency can be different. Nectar greatly affects visitor behaviour and fidelity to a certain species, influencing plant reproductive effort. In this study we have investigated a generalist system (Gentiana lutea L.), examining the role of flower visitors and quantifying the contribution of each pollinating taxon in three natural populations. In order to verify the level of generalization, we introduce an index of Pollinator Performance (PoP), based on insect visitation rate and cross-pollen transport efficiency. Our results confirm the high degree of pollinator-generalization of the study species. Nevertheless, flower visitors show various degree of pollinating performance, mainly defined by their sedentary versus dynamic behaviour. Sedentary insects enhance geitonogamous pollen transfer, which results in reduced seed set and pollen limitation. In particular, an unusual sluggish behaviour was observed in bumblebees feeding on nectar. The hexose-rich abundant nectar offered by G. lutea flowers is remarkably rich in proline and β-alanine amino acids: this composition presumably influences feeding choice and insect dynamism, likely exerting a narcotic effect on pollinators. The consequences on plant fitness are discussed in an evolutionary perspective.
Martina Rossi;Alessandro Fisogni;Massimo Nepi;Marino Quaranta;Marta Galloni
File in questo prodotto:
Eventuali allegati, non sono esposti

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/253142
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 14
  • ???jsp.display-item.citation.isi??? 14
social impact