beetlebellyeasts
Biotic Surveys & Inventories
This is a collaborative project funded by the National Science Foundation Grant No. 0072741 (May 2001 to 2003)
© Sung-Oui Suh, Meredith Blackwell, and Joseph V. McHugh
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Sung-Oui Suh and Meredith Blackwell

Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803

Joseph V. McHugh
Department of Entomology, University of Georgia, Athens, Georgia 30602


Beetles and their yeast endosymbionts from basidiocarp habitats
Panama 2001(photographs)

Home / Introduction / Participants / Basidiocarps as habitat / Insects / Yeasts / Methods / Publications / Literature cited / Proposal I / Proposal II / Mycology at LSU
Introduction Over the last century the recognition of the presence of endosymbionts in a variety of arthropods has become well established. Intense interest in the prokaryotic rickettsial endosymbionts, widespread among insects (van Meer, Witteveldt, and Stouthamer, 1999), has led to the discovery that the rickettsia may induce sterility of the host. Thus, speciation or increased rates of speciation have been attributed to the presence of the symbionts (Shoemaker, Katju, and Jaenike, 1999). By contrast, although there were a number of early reports of fungal endosymbionts of insects, few of them were substantiated (Buchner, 1965). Until now, yeasts and yeast-like fungi have been known from the gut only of a small group of planthoppers (Homoptera) and of three families of beetles (Coleoptera: Anobiidae, Cerambycidae, and Scolytidae) (Table 1).  We believe that eukaryotic endosymbionts play an equally important role in insect evolution, and the example of Symbiotaphrina in detoxification of food resources for anobiid beetles (Dowd, 1989, 1991) supports this contention. Another system, although not endosymbiotic, the cactophilic yeast-Drosophila associations studied by Starmer and his colleagues (Starmer et al., 1991) provides another example of the influence that yeasts have in ameliorating the nutritional resources of insects.
 
Previously known  species of yeasts and yeast-like  endosymbionts in insects*
Host insect /Fungus species
Homoptera
    Nilaparvata lugens/undescribed hypocreatean fungus
    Sogatella furcifera/undescribed hypocrealean fungus
    Laodelphax striatellus/undescribed hypocrealean fungus
Anobiidae
    Lasioderma serricorne/ Symbiotaphrina kochii
     Sitodrepa paniceae/ Symbiotaphrina buchneri
     Ernobius abietis/ Candida karawaiewii
     Ernobius mollis/ Candida ernobii
     Xestobium plumbeum/ Candida xestobii
Cerambycidae
    Rhagium inquisitor/ Candida rhagii
     Rhagium  mordax/ Candida tenuis
     Rhagium bifasciatum/ Candida tenuis
     Rhagium sycophanta/ Candida tenuis
     Gaurotes virginea/ Candida rhagii
     Leptura rubra/ Candida tenuis
     Leptura maculicornis/ C. shehataevar. insectosa
    Leptura cerambyciformis/ C. shehataevar. insectosa
     Leptura sanguinolenta/ Candida sp.
    Phoracantha semipunctata/ Candida tenuis
     Microplophorus magellanicus/ Candida tenuisand Rhodotorula glutinis
     Grammicosum flavofasciatum/ Candida parapsilosisvar. intermedia
     Ergates faber/ Candida ergatensis
Scolytidae
    Dendroctonus monticolae/ Candida nitratophila
*The list has been modified from that of Nardon & Grenier (1989).

Recently we discovered a species-rich association between gut-associated endosymbiotic yeasts and basidiocarp-inhabiting beetles; the beetles presumably use fungi to eat fungi.  Beetles in the families we examined with this habitat routinely harbor distinctive yeasts. Placed in the context of previous knowledge of endosymbiotic yeasts in only three families of beetles (see table above), our finding of endosymbionts in seven out of the eight beetle families examined randomly (PDF) portends the success of the project.


Preliminary results Our preliminary results are intriguing. We have increased the number of coleopteran families known to harbor endosymbiotic yeasts from three to eight (see table above) by looking at members of the first six beetle families we encountered. Many of the taxa are undescribed species of Saccharomycetales that appear to have strict associations with particular groups of mycophagous beetles. We chose basidiocarps of agarics, boletes, puffballs, and polypores as habitats in which large numbers of taxonomically diverse beetles could be collected repeatedly at different localities; discovery of new species of yeasts in the gut of beetles feeding in these habitats far exceeded our expectations. In fact of the six beetle families randomly sampled, only one (Staphylinidae: Bolitocharini) lacked yeast associates! The beetles were collected from basidiocarps (Amanita sp., Boletus sp., Inonotus ludovicianus, Ganoderma lucidum, Fomitella supina, and Pisolithus tinctorius) in southern Louisiana and Athens, Georgia. The target basidiocarps occur widely and are relatively easy to spot in the field; they harbor a diverse group of beetles. Beetles have been found repeatedly at different localities in the eight months of the year in which we sampled.

The preliminary data have lead us to the following conclusions:


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Literature cited

This material is based upon work supported by the National Science Foundation under Grant No. 0072741. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

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Last update: 5 May 2001
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