Leukocytes that respond to nonspecific foreign invaders are called while respond to specific invaders.

Leukocytes that respond to nonspecific foreign invaders are called Phagocytosis while Lymphocytes respond to specific invaders.

Explanation:

Phagocytosis: It is process where phagocytes are engulfed or ingest foreign particles. Phagocytes are may be body cells like white blood cell or may be free living single celled organism.

Leukocytes, they are involved in the process of ingestion of particles, pathogen recognition, pathogen distraction and antigen presentation.

Lymphocytes are also white blood cells which is main type of immune cell in body. They are synthesized in bone marrow and present in the lymph and blood tissues. Lymphocyte main function is, they are the part of immune defense, and they are producing antibodies by recognition of the antigen.

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.