You Do Need power plug adapter while traveling from Pitcairn Islands to Bonaire.

Here is Why You Need An Adapter

The outlet and plug type used in Bonaire are A and C and in Pitcairn Islands is I. This is how they look like.

Pitcairn Islands

In Pitcairn Islands, outlets of type I are in use.

Type I

Bonaire

In Bonaire, outlets of type A and C are in use.

Type A

Type C