Answer:
There is a decrease in the potential energy and a relative increase in the kinetic energy of the charge.
Explanation:
The direction of the electric field and that of the force acting on a positively charge particle is same while in case of a negative charge the force acts in the opposite to that of the electric field field.
When the negative charge moves in the direction opposite to that of the electric field then work is done on the charge and is thus positive which means the potential energy associated with the charge reduces and is stored in the vicinity of the field while there is a relative increase in the kinetic energy of the charge.
When no other force is present like that of gravity, etc, the energy remains constant thus a decrease in one form is compensated by a relative increase in the other form of energy.