Lee Cook's fourth-minute shot from the right-hand side of the penalty box was enough to separate the sides.
Brendan Moore denied Cook a second in the first half while Angus MacDonald twice went close for the Gulls.
Torquay, who had been on an eight-game unbeaten run, have now lost two in a row and are two points from safety.
They have scored just one goal in their last six games and dropped to third from bottom of the table after Boreham Wood's 3-0 win over Dover.

England won the day-night Test - the first game in the three-match series - by an innings and 209 runs inside three days at Edgbaston.
West Indies have not won a Test in England for 17 years.
"Every time they have arrived in England, they seem to have got worse," Vaughan told BBC Test Match Special.
West Indies lost 19 wickets on Saturday to be bowled out for 168 and 137 in reply to England's 514-8 declared.
Their squad is without established stars Chris Gayle, Dwayne Bravo and Darren Sammy after a disagreement with Cricket West Indies over selection.
However, their decline from the all-conquering side of the 1980s can be traced back to the mid-1990s - they have not won a series away from home against a team other than Bangladesh and Zimbabwe since 1995.
"There are a lot of young players in the West Indies side and you need to give them time, but I find it difficult to think they can go on without any senior players," said Vaughan, who captained England in 51 of his 82 Tests.
"There is no one there to teach them. I really fear that this series could be one of the saddest for Test cricket."
England, who were rated as the worst team in the world in 1999, drew a three-Test series in West Indies as recently as 2015.
"I don't think this era of cricket is any different to any other era," said England coach Trevor Bayliss.
"There have always been strong teams and one or two that are struggling.
"West Indies are going through a rough time but 20, 40, 60 years ago there were other teams that were going through rough periods."
England captain Joe Root said West Indies' display should not detract from the performance of his side, who beat South Africa 3-1 in their previous Test series this summer.
"We talk about being ruthless," he said. "We played some really good cricket and it's important we look to back that up."
Jermaine Blackwood, who scored an unbeaten 79 off 76 in the first innings, was the only West Indies batsmen to pass 40 in a game in which England's Alastair Cook made 243 and Root 136.
West Indies skipper Jason Holder said: "We just weren't up for scratch.
"We lacked consistency when we bowled and we didn't put up any runs in either the first or the second innings.
"Each player has to look themselves in the mirror and see in what way they can improve.
"It's important for us to regroup. This series is not lost. It's important we don't drop our heads. Obviously I believe. I have to believe."
The day-night Test, the first to be held in the UK, was arranged partly to help England prepare for the Ashes, where they will meet Australia in a floodlit Test in Adelaide.
"To have a taste of it before the Ashes is important," said Root.
"The visuals of the ball, getting used to batting at different points in the day, there will be different challenges that lie ahead.
"But to play in that environment and to know what it's about is a good thing moving forward."
Eastleigh moved to within two points of the National League play-off places as they won at relegation-threatened Torquay United.
[NEXT_CONCEPT]
The remainder of England's series against West Indies will be "sad to watch", says former England captain Michael Vaughan.