Registrant

n. one who registers, one who enrolls; one who is registered, one who is enrolled

Noun
1. a person who is formally entered (along with others) in a register (and who obtains certain rights thereby)
(hypernym) person, individual, someone, somebody, mortal, human, soul
(derivation) register

v. register, calendar

(n.)
One who registers; esp., one who , by virtue of securing an official registration, obtains a certain right or title of possession, as to a trade-mark.
  

Any manufacturer or formulator who obtains registration for a pesticide active ingredient or product.