The results presented here show that all the three strains of A. nidulans have extremely low or zero larval
morbidity. The studies on host specialisation of Aspergillus species by St. Leger et al. [20] identified A.
nidulans as non-pathogenic for G. mellonella larvae. However they used just 3000 spores per larva and spore
numbers were deduced from microscopic counts only and therefore many spores may not have been viable. In
the present study, spores of A. nidulans laboratory strain (STA171) were completely avirulent even although
the inoculum size was much larger than that used by St. Leger and a genetically wild type strain was used in
this study. Moreover, number of viable spores for strain C49 did not bring about large fatalities. It has been
reported in A. fumigatus [25] also Cryptococcus neoformans [26] that the killing correlates to the inoculum
size. The number of viable spores of C49 that injected to each larva was 48,000, more than the double counted
for the other two strains, STA171 and C51.