The food chain describes the feeding relationships between species. You have to carefully keep an eye on which predators have access to which prey in order to keep a robust garden. (While predators might not actively eat a prey, you may need to actively give up one of the prey, to be consumed for advancing a requirement.) Some pinatas may not eat each other, but they may not get along so well and fight often.
You may be able to stop a predator from eating its prey by dousing it with water, whacking it with a shovel, or keeping it behind a strong fence.
Basically, insects are eaten by birds and small mammals, which are themselves lower down the ladder than birds of prey and land predators.