The tiny invaders being discussed in the article are plants. They are considered invaders because they came from other countries, but are now threatening the native plants. People brought them in because they wanted to make their gardens and yards beautiful because the plants are very rarely found locally.
The suspect does not admit guilt, but does not wish to fight the charges and does not want a trial.
For cultivation, i believe you mean the agricultural definition, and if so, it would be a plow
He will tell of their greatness when he returns
