Submitted to: Psyche
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2012
Publication Date: 3/26/2012
Citation: Cottrell, T.E., Riddick, E.W. 2012. Limited transmission of the ectoparasitic fungus Hesperomyces virescens between lady beetles. Psyche. 2012(814378):7.
Interpretive Summary: An ectoparasitic fungus [Hesperomyces virescens Thaxter (Ascomycota: Laboulbeniales)] commonly infects the invasive multicolored Asian lady beetle Harmonia axyridis (Pallas) and several other predaceous lady beetles in North America and Europe. We did tests to determine if the fungus could be transmitted from infected to non-infected lady beetles. Results indicate that fungus transmission between beetles readily occurs when the infected and non-infected beetle are the same species. Limited transmission was found to occur between beetles when the infected and non-infected beetles were different species. Based upon our laboratory assays of forced pairings/groupings of infected and non-infected lady beetles, we predict that transmission of this ectoparasitic fungus between species of predaceous coccinellids is possible but likely rare.
Technical Abstract: The ectoparasitic fungus Hesperomyces virescens Thaxter (Ascomycota: Laboulbeniales) commonly infects the invasive lady beetle Harmonia axyridis (Pallas) and several other aphidophagous lady beetles in North America and Europe. We tested the hypothesis that bodily contact between adults of different lady beetle species supports horizontal transmission of H. virescens. We used laboratory assays to determine whether H. axyridis or Olla v-nigrum (Mulsant) harboring H. virescens (i.e., source beetles) transmit the fungus to non-infected target beetles H. axyridis, O. v-nigrum, Coccinella septempunctata L., Coleomegilla maculata (De Geer) or Hippodamia convergens Guerin-Meneville. Results indicate that intraspecific transmission (i.e., for the source beetles H. axyridis and O. v-nigrum) was common but interspecific transmission (i.e., from source H. axyridis or O. v-nigrum to target species) was low. Interspecific transmission occurred at low rates from H. axyridis to both C. septempunctata and O. v-nigrum and from O. v-nigrum to both C. septempunctata and H. convergens. Based upon our laboratory assays of forced pairings/groupings of source and target beetles, we predict that horizontal transmission of H. virescens between species of aphidophagous coccinellids is possible but likely rare.