Question

why weed and wild plants are not affected by insects and pests?

Answer 1

Weeds and wild plants can be affected by pests, such as insects. However many wild plants have a natural resistance, or resilience against predators, which they have gained through years of natural selection and adaption.  

Wild plants protect themselves in the following ways:

1.    Plants produce chemicals which repel or poison insects.

2.    Plants produce chemicals designed to reduce palatability.

3.    Plants have a thick waxy cuticle covering soft tissues, such a leaves, which acts as a physical barrier against predation.

Answer 2

Weeds and wild plants can be affected by pests, such as insects. However many wild plants have a natural resistance, or resilience against predators, which they have gained through years of natural selection and adaption.  

Thus weeds and wild plants are not effected by insects and pests