A new obligate mutual pollination system involving Boronia (Rutaceae, Sapindales) and Heliozelidae (Adeloidea, Lepidoptera)

A project undertaken at the Walter and Eliza Hall Institute of Medical Research and supervised by Axel Kallies

Obligate pollination mutualisms are rare, highly interdependent relationships between co-evolved insects and plants. The best known examples involve figs and fig wasps and yuccas and yucca moths, where the insects are required for pollination and plant survival, and the plant is the sole larval food source, hence essential for insect survival. These systems allow exploration of how co-evolving species interactions may arise and stabilise, and subsequently are exploited by "cheaters". 

As part of our unpublished study of Australian Heliozelidae (a family of small, day-flying moths), we have identified many new genera and species. Unlike leaf-mining Palearctic and Nearctic Heliozelidae, many Australian species lay eggs into flowers, with larvae consuming seeds. One major clade of Heliozelidae appears to be tightly associated with the Rutaceae plant family. Within this clade, we have found a new genus with a unique pollen collecting structure on its abdomen, which appears to act as the obligate pollinator of Boronia megastigma and its close relatives. The Boronia hosts have other Heliozelidae associated with them that appear to play no role in pollination but rather exploit or "cheat" the system.

The Boronia-Heliozelidae relationship is significant because unlike other mutualistic systems, Boronia species outside of the megastigma group appear to have generalist heliozelid pollinators, facilitating the exploration of the emergence of an obligate system. In addition, the small size of Boronia and their rapid development to maturity make them a tractable system to study. The goal of this project is to characterize the morphology and ecology of the pollinator and ‘cheater’ heliozelid moths, and scientifically describe them, thereby allowing their further study by ecologists and conservation groups.