ODC1 and malaria: We show that the presence of Pe. chrysogenum in the mosquito midgut does not influence mosquito longevity but instead its susceptibility to the malaria parasite Plasmodium. We further show that the molecular basis of this phenomenon likely involves fungus-mediated upregulation of ornithine decarboxylase (ODC), sequestering L-arginine for polyamine biosynthesis and thereby resulting in diminished production of anti-parasitic nitric oxide (NO).