The on-loan striker staked his claim for a permanent deal at the Liberty Stadium by scoring the only goal of Tuesday’s game seven minutes after coming on as a half-time substitute.
Trundle is due to return to parent club Bristol City at the end of the month, but the Liverpudlian could well have earned himself a longer stay in Wales after notching his fifth goal of the season.
To compound the Pilgrims’ misery, Shane Lowry was sent off for a second bookable offence in stoppage time after a scuffle with Gorka Pintado.
Swansea are now unbeaten in nine league matches at home.
Struggling Argyle have failed to score in three matches and are second-bottom after their 12th league defeat of the campaign.