Adkins angered by slack defending
Goals from Mark Wright and Jim McNulty gave the Seagulls a comfortable victory at Glanford Park - much to the disappointment of Adkins.
"We were very poor defensively, any time the ball went anywhere near our goal we looked like we were going to concede," he said.
"As a team we were nowhere near good enough defensively. The players have been made well aware of that."
United play again on Tuesday night when the Premier League side Wolves visit Glanford Park, the last outing before the season-opening trip to Cardiff City on Saturday.
"I expect hard work and commitment from the players and that wasn't good enough," added Adkins.
The Brighton manager Russell Slade asked his side to display the same endeavour when league points are at stake from next week.
"What I will promise is we will have the most honest and hard-working team in the league," he said.
"There was some good football and we created a lot of chances. It could have been 3-3 in the first 20 minutes but we got a foothold in the game, got the goal, and never looked back."