I'd guess that that monoculture, pesticides and fertiliser make up the bulk of the insect problem. However, in terms of potential for unforeseen catastrophe, I

I'd guess that that monoculture, pesticides and fertiliser make up the bulk of the insect problem. However, in terms of potential for unforeseen catastrophe, I'd leave GMO in the list. Our understanding of how small genetic changes can affect ecosystems in unintended ways is far, far from thorough. W don't even understand how small genetic changes affect us, never mind a biome filled with biomes.