Given licence to live in the backline, Kubunavanua and his Fijian brethren tore the diminutive-looking Colt outside backs apart, both down the tramlines and through the middle of the park.
Dibben opened his account with Wanganui's second try in the ninth minute, following captain Kieran Hussey's opener, and after that only prop Manu Hearing collecting a loose ball close to the line would be a forward's try.
Dibben, who is likely to find himself in the frame for the Heartland lineup this Saturday, scored back-to-back tries after the half-time break, despite the momentary distraction of some feeble tackling attempts.
First-five Areta Lama called his own shots and even found risky grubber kicks inside Wanganui's half could be regathered for waltz-away tries.
Development coach Shane Ratima will still take some 'work-ons' out of the match as a couple of Wanganui fumbles and a series of penalties opened things up for Colts' No8 Dominic Trewavas, winger Wiremu Taui and lock Dan McCool to score consolation five-pointers.
But none could stop Dibben, who just ran around his markers in the middle of the field for two more tries, actually jogging slightly away from the posts as he crossed the line for his fifth to give secondary goal-kicker Kane Tamou a little more of a challenge after his first three conversions were right in front.
Dibben could even have had a sixth try at the end of the game, yet gave a generous pass with the line open, only to see it spilled.
Wanganui Development 79 (S Dibben 5, A Lama 2, K Hussey, S Kubunavanua, S Naqiso, M Hearing, S Radradra, M Andrews tries; K Tamou 4 con, S Ulukuta 3 con) bt Wellington Maori Colts 19 (D Trewavas, W Taui, D McCool tries; L Grace 2 con). HT: 41-0.