Ectoparasitic mite and fungus on an invasive lady beetle: parasite coexistence and influence on host survival

This study documents the interaction of two coccinellid-specific ectoparasites, a podapolipid mite Coccipolipus hippodamiae (McDaniel et Morrill) and a laboulbenialean fungus Hesperomyces virescens Thaxter with the lady beetle Harmonia axyridis (Pallas). The study objectives were to (1) determine the prevalence and intensity of both parasites and (2) predict the influence of parasitism on host survival during the winter season. The prevalence of mite and fungus in host aggregations ranged from 3.2 to 17.4% and 3.6 to 43.5%, respectively, in winter aggregations in five different locations in Mississippi, southeastern USA, from 2007-2009. The mite colonized the subelytral space of male and female H. axyridis. Mite intensity was greatest on fungusinfected beetles, especially females. Fungus intensity was greatest on the abdomen of H. axyridis males that harbored mites than those that did not. H. axyridis adults (particularly males) infected with the mite and fungus or the fungus alone had lower survival rates, under simulated winter conditions, than those not infected with any parasites. This research documents the parasitic mite C. hippodamiae infecting H. axyridis under natural field conditions for the first time anywhere in the world.