Pathogenicity by Aspergillus flavus from Gulf Coast tick cadavers (Amblyomma maculatum, Acari: Ixodidae) to any life history stage

A natural aspergillosis in the Gulf Coast tick, Amblyomma maculatum, is reported for the first time. Under high relative humidity (RH) conditions, field-collected adults died and became enveloped in whitish mycelium from hyphae that protruded from their bodies. The fungus was identified as Aspergillus flavus. Laboratory-colonized eggs, larvae, nymphs, and adults displayed disease symptoms, and A. flavus was reisolated from dead individuals, about 10 days after artificial infection by submersion for 2 minutes in a 1.6 x 10(8) spores/ml + Tween 20 inoculum of the native A. flavus isolates. Treatment-related mortality was 87% larvae, 67% eggs, and between these extremes for nymphs and adults. Increased water loss rate was a pathogenic consequence of A. flavus infection for all stages. We conclude that A. flavus is a natural regulator of A. maculatum populations, and larvae are particularly susceptible because of their low dehydration tolerance limit.