It's well known that reactive oxygen species (ROS) and reactive nitrogen species (RNS) are used to fend off both infection and non-cooperative host cells i.e. c

It's well known that reactive oxygen species (ROS) and reactive nitrogen species (RNS) are used to fend off both infection and non-cooperative host cells i.e. cancerous cells. But nitric oxide (NO) can spontaneously react to nitrite (NO2-) and nitrate (NO3-), and nitrate can actually be used as an electron acceptor by some bacteria in mouse intestines. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3705454/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3705454/) The article points out that wasps transfer protective bacteria to their larvae, so it could have been that secreting NO is really just an indirect way of cultivating more of these helpful bacteria. However, they showed that the protective effect against mold was the same whether or not nitrate was present, which shows that the mechanism really is direct killing of the mold by the eggs themselves!