The effect of fungal ribosome inactivating proteins upon feeding choice in C. freemani, and indications of a mutualistic relationship with A. restrictus. Environmental mycology

Carpophilus freemani beetles' feeding on the fungus Aspergillus nidulans was substantially inhibited when A. nidulans was transformed and induced to secrete the ribosome inactivating protein, restrictocin (genetic source: Aspergillus restrictus). No inhibition of feeding was observed when A. nidulans was transformed and induced to produce an inactive form of restrictocin with a single amino-acid substitution in the active site. Similarly, there was no inhibition of feeding upon transgenic strains when the production of restrictocin was not induced. Feeding inhibition of C. freemani by restrictocin requires that the ribonuclease be active and is not due to other characteristics of the protein or the transgenic host fungus.