You Do Need power plug adapter while traveling from Saint Lucia to Niger.

Here is Why You Need An Adapter

The outlet and plug type used in Niger are C, D, E and F and in Saint Lucia is G. This is how they look like.

Saint Lucia

In Saint Lucia, outlets of type G are in use.

Type G

Niger

In Niger, outlets of type C, D, E and F are in use.

Type C

Type D

Type E

Type F