The Merseysider bagged his ninth and tenth goals of the season with two quality finishes and he could have had a hat-trick by the 23-minute mark as he also fired an effort onto the post.
Crewe's weak underbelly was exposed by the South Wales side's clinical finishing.
The hosts' hopes of getting back into the promotion race suffered an early blow when Trundle turned on Andy Robinson's free kick and fired low and hard into the bottom corner from 15 yards.
The Swansea front man was a constant menace early on, flicking a free kick off the defensive wall and just over the bar while his volley came back off the inside of the post and flew across the face of Stuart Tomlinson's goal.
However the young keeper could do nothing when Trundle took Rory Fallon's pass and volleyed in off the far post from an acute angle.
Crewe were shell-shocked and it took them until well over the half-hour to pose their first threat but Ryan Lowe's 25-yarder landed straight into Willy Gueret's midriff.
Crewe caved in again two minutes after the break when Tomlinson failed to get a punch on a corner kick and Trundle crossed for giant centre-half Dennis Lawrence to head in.
But despite being three down, Crewe did keep fighting and they enjoyed their best spell of the game which culminated in Luke Varney netting his 14th goal of the season when he finished off from close range after Gueret spilled Nick Maynard's shot.
Varney just missed out touching Lowe's free kick in at the far post and then shot straight at the keeper, while Maynard lifted an effort over as Crewe piled on the pressure.
But it proved to be too little too late for the Railwaymen and Swan's substitute Adebayo Akinfenwa almost killed the game off when he held the ball up baffling the posse of Crewe defenders before firing just past the far post.