Could a biological caste system be effective to control a populace?

Question

I'm creating a story with a biological caste system based on different species of ants. There are soldiers, farmers, and builders, each with biologically different bodies in order to keep factions separate. Would this work? A group of royals rules over the factions, attempting to keep the groups separate in order to avoid war or riots that could be caused if the factions united.

To be clear, the different factions cannot breed with each other, and only speak to each other when necessary. Their jobs also prevent them from interacting with each other. The royal faction reigns supreme. Sorry if I didn't make that clear. If the castes united, they'd rebel against the Royals in order to make the society a capitalist democracy.

The royals stopped genetic manipulation a long time ago. Since then, they've lost the technology. There are multiple societies like this, hence the need for soldiers. Members are non-reproductive. A machine creates the members using pre-existing and cloned reproductive "stuff" in various combinations. Every so often the royals collect new "stuff" to input into the machine, but they've lost the knowledge of how to interface with most of the technology that makes up the machine. The members do have some level of self-determination. There is an economy between factions and governments.

The machine does not breed between castes, because the members literally cannot breed with each other without the help of the machine, as they have become different species. As for mating, the instinct to breed has been genetically engineered out of them, or otherwise prevented. For example, all soldiers are nearly identical clones of each other, with only slight differences like markings that represent rank.

Answer 1

Of course!

Like any oppressive society, elites can control people and enforce their own rule. The key isn't separation, but separate expectations and motives. I question that a rebellion would lead to a capitalist democracy, but if this is the rival system to the autocratic genetic command economy, then that could make sense. The genetics just add an extra layer to oppression, so the rules of control apply that make oppressive societies everywhere function. The only difference is, there's no way for talent to gain status. So make your non-elites subservient.

Have you read Brave New World? There, the classes are controlled by brainwashing from before birth, and deliberate brain damage in the least of society. Aldous Huxley would have used genetics more if the rules were understood better in his time. Each class was made to love their own position and be happy.

• Elites should be like Aristoi. They should live relatively clean lives and not give their servants reason to envy them. Time should be devoted to thought and education. This group needs to be the least stratified, as they have to be able to understand the jobs and functions of all other classes.
• Your most likely source of rebellion is the military. They could overthrow the elites and simply kill anyone that defied them, so control them with some strong compulsion. Pheromones and tradition are good starts. Elites just FEEL right, and after all, someone needs to be in charge, while everyone knows the military is the real source of power. Elites need to either be the generals, or else the generals need to be especially controlled. I would suggest the generals have explosives implanted in their heads as part of being a general if they aren't already elites. Mostly, make being in charge a headache - literally. Thinking about control causes headaches, and trying to do more than petty domination causes searing pain.
• Workers can control society, but make them so they can't form strong motivations. They should be simple, passive creatures, who would freeze or die of starvation if not told to harvest the crops, build the buildings, and perform all the tasks not specifically laid out in instruction manuals. They should need and crave instruction, and forcing them to make decisions should cause crushing anxiety and stress. They are so glad no one makes them decide things, and every problem has a solution laid out in an instruction guide. If not, there's an Elite to ask questions of who'll tell you it's okay and give you an answer.

Answer 2

Ant colonies only work because all the castes are siblings they are literally more closely related to each other than offspring. If they can breed independently there system is not stable long term, there is a huge selective pressure to screw over the other castes.

Your second problem is in society there is a lot of crossover in jobs, a irrigation system builder who does not understand farming is doomed to be very bad at it.