What does Plant Toxins have to do with Coevolution?

Question

if u could help me quickly it would be great

Answer 1

Plants use their toxins (or secondary metabolites) to prevent herbivores, especially insects, from doing as much damage. They may also secrete them into the ground for an allelopathic effect tp prevent other plants from growing so close.

Once these factors have been in place the hungry insect that can tolerate the toxin better than  another has the advantage of a food source that no other insect prefers.  The milkweed contains a latex that prevents the insects digestion and gum up their mouth parts. Monarch butterflies have adapted to tolerate this latex to the exclusion of all other food sources.  Now they only lay their eggs on milkweeds. Further the butterfly caries the toxin for its own protection from predation by birds.

Another example is tobacco and the hornworm that survives dining on nicotine.

Answer 2

insects drank nectar from plants to make food and the plants died or became weak so over time plants nectar change into toxins to protect itself and the insects had to evolve b/c they lost a food source

I'm not entirely sure