In farming, before you farm, you are supposed to consult experts to guide you not the other way round. Before you plant your yam seeds in your heaps/moulds, you were supposed to have treated them by soaking your seeds in a chemical solution that will keep termites and yam beetles away from your yams or you spray insecticide treatments inside the heaps before planting. Another pre-planting method is to rub Adrian Dust all over your seeds before planting.
Humans defication is a big enemy to termites. You can also try that.
* Will animal faeces like cow defication work?
It must be human faeces. Or try poison garri for them.