Virulence of three Aspergillus species to the model insect Galleria mellonella and the contribution of ergot alkaloids to the pathogenic potential of Aspergillus leporis

Opportunistically pathogenic fungi have varying potential to cause disease in animals. Factors contributing to their virulence include specialized metabolites, which is some cases evolved in contexts unrelated to pathogenesis.  Specialized metabolites that increase fungal virulence in the model insect Galleria mellonella include the ergot alkaloids fumigaclavine C in Aspergillus fumigatus (syn. Neosartorya fumigata) and lysergic acid α-hydroxyethylamide (LAH) in the entomopathogen Metarhizium brunneum. Three species of Aspergillus recently found to accumulate high concentrations of LAH were investigated for their pathogenic potential in G. mellonella.  Aspergillus leporis was most virulent, A. hancockii was intermediate, and A. homomorphus had very little pathogenic potential. Aspergillus leporis and A. hancockii emerged from and sporulated on dead insects, thus completing their asexual life cycles. Inoculation by injection resulted in more lethal infections than did topical inoculation..., Larvae of the model insect Galleria mellonella were purchased from Josh’s Frogs (Owosso, MI) and injected with conidia (20 µL at 3,000 conidia/µL, or in one experiment 250 conidia/µL) of Aspergillus leporis, A. hancockii, and A. homomorphus with the aid of a 29-gauge insulin syringe. Control groups of 12 to 15 larvae per trial were injected with 20 µL of PBS solution (phosphate buffered saline) lacking Aspergillus spores. Injected larvae were incubated at room temperature (or in one trial at 37 °C) and observed for one to two weeks following inoculation; any dead larvae were removed throughout this period. Insects also were inoculated topically by placing larvae on sporulating cultures on sucrose-yeast extract agar (20 g sucrose, 10 g yeast extract, 1 g magnesium sulfate heptahydrate, and 15 g agar per liter) for 24 hours before removing them to empty Petri dishes.  Insects inoculated through this topical, or natural, approach were observed for 16 days following inoculation. 
Alkaloids ..., Data are in a single MS Excel file with six separate tabs.  Data are ready to be copied and pasted into a JMP worksheet.