Mandadapu is a surname of people living in parts of Guntur district of Andhra Pradesh region in India. This surname belongs to the subsect of brahmins called niyogi. Prathama Shakha Niyogi is a subsect of Niyogi. Generally niyogi and specifically Prathama Shakha Niyogi have these types of surnames.
References
Mandadapu Wikipedia(Text) CC BY-SA