When Crusher saved Lenny's life, the two of them had to circumnavigate a longer route before coming back to meet up with his gladiator friends.
Within that long time he was gone, one of the praying mantis insects had discovered the hiding points of the gladiators and relayed the message to old man Buckle.
Insect B was injured, and in her angry state, she wanted nothing more than to kill the gladiators. However, old man Buckle had advised against it.
Instead, he made a deal with the gladiators, guaranteeing their lives if they led Crusher and Lenny to him.
The deal was struck, and the gladiators seeking freedom from this hell hole chose to side with old man Buckle and Insect B.