Generalised pollination systems for three invasive milkweeds in Australia

Area of Science:

• Ecology
• Botany
• Conservation Biology

Background:

• Plant invasiveness is often linked to successful establishment of ecological relationships, including pollination.
• Milkweed species (Asclepias, Gomphocarpus) are invasive in Australia, challenging assumptions about specialized pollination systems hindering invasion.
• Understanding the pollination ecology of invasive species is crucial for predicting and managing their spread.

Purpose of the Study:

• To investigate the pollination ecology of three invasive milkweed species in Australia.
• To determine if specialized or generalized pollination systems contribute to their invasive success.
• To assess the role of pollinator interactions in the establishment of introduced plant species.

Main Methods:

• Field observations of flower visitors on Asclepias curassavica, Gomphocarpus fruticosus, and Gomphocarpus physocarpus in Queensland, Australia.
• Identification of key pollinator groups for each milkweed species.
• Analysis of floral nectar rewards.

Main Results:

• Pollination systems were specialized at the order level but generalized at the species level.
• Asclepias curassavica was primarily pollinated by Lepidoptera (nymphalid butterflies).
• Gomphocarpus species were pollinated by various Hymenoptera (vespid wasps), with all species offering abundant nectar.

Conclusions:

• Generalized pollinator requirements likely contribute to the invasive success of these milkweed species.
• The study highlights the importance of considering pollinator generalization in predicting plant invasions.
• Data from native ranges could inform predictions of pollination success in new environments.