Endemic Hawaiian yeasts

and Hawaiian sap beetles

With the exception of species that feed on pollen, all of the endemic Hawaiian sap beetles apparently feed on fungi: both single celled (yeasts) and mycelial, and from both the ascomycetes and basidiomycetes. Andre Lachance of the University of Western Ontario in London Ontario has been studying the relationship between yeasts and sap beetles for over 20 years. The Hawaiian sap beetles can be reared from the same substrate as the famous Hawaiian Drosophila, though the beetles emerge later, and the Drosophila larvae consume primarily bacteria while the sap beetles consume fungi.  The two most important hosts for the Drosophila are Cheirodendron and Clermontia, a preference shared by the Hawaiian sap beetles.  

Left Marc-André Lachance, Molokai, Kamakou TNC preserve, inspecting Clermontia kakeana. Right C. Ewing and A. Lachance extracting sap beetles from C.kakeana stick . Photos: Jane Bowles

Many species of endemic Hawaiian sap beetles found in fresh flowers are associated with yeast, which is a general term for any single celled fungus. The most well studied relationships are between sap beetles in the genus Prosopeus and the ascomycete yeast genera Metschnikowia and Candida. Metschnikowia and Candida species were originally isolated in Hawaii from an introduced sap beetle, Conotelus mexicanus, from morning glory flowers in Kipuka Puaulu near Kilaeuea on Hawaii Island. Additional sampling revealed an association between the yeasts, morning glories, and an endemic Hawaiian sap beetle, Prosopeus subaeneus (=Nesopetinus scottianus).

André Lachance, Jane Bowles, and Curtis Ewing have recently sampled native sap beetles in native flowers of: Ilex anomola (kāwa'u), Clermontia spp. (haha), and Broussaisia arguta (Kanawao) and isolated new species of Metschnikowia.

The Metschnikowia species endemic to Hawaii belong to the large-spored group. The ascospore length varies between species, from 20-25 in Metschnikowia drosophilae, to over 200 micrometers in Metschnikowia lochheadii and Metschnikowia hawaiiensis, as shown below.

The yeasts : A taxonomic study / edited by Cletus P. Kurtzman and Jack W. Fell. New York, Elsevier, c1998. 4th ed.