"If the City Lord and merchants are interested in the termination of the Mutated Gluttony Termite Queen, it makes sense that they are willing to pay handsome rewards for the mission. If the Mutant Gluttony Termite Queen were to kill the old Gluttony Termite Queen with a suicidal onslaught the manufacturing of the beauty products would stagnate, resulting in a much bigger loss."
It was even possible that the Mutant Gluttony Termite Queen would die while killing the old Gluttony Termite Queen, which would inevitably stop the whole manufacturing process of the beauty products.
For a moment Zayn was sad because he had hoped that he could kill both colonies of Gluttony Termites but that feeling quickly disappeared when he realized the true worth behind the Gluttony Termite Queen hunting mission.
One could easily earn a fortune by collecting the gel-like substance of the Gluttony Termites, followed by a big reward for the completion of the mission as well.