More recently she slashed more than a second from her 400m flat personal best of 53.97 in New York to earn her berth in the latter event.
Waddell now emulates her mum and coach, Sonia Waddell, who represented her country in the 400m hurdles at the 1990 World U20 Championships.
Two-time World Cross Country Championships representative Ritchie, the national U20 800m and 1500m champion, competed in the two-lap event in the previous edition in Cali, Colombia two years ago and boasts a PB of 2:06.51 set in Hastings in January.
“Our U20 athletes have produced a series of excellent results over a range of events so far this year and this has been reflected in a strong team which has secured selection for Lima,” Athletics New Zealand high-performance athlete development leader Tim Driesen said.
“The World U20 Championships represent a great gauge for where our athletes match up to the rest of the world, and I can’t wait to see how they perform in late August.”
World Athletics World U20 Championships initial NZ team
Women
100m - Addira Collette (Palmerston North AC)
400m/400m hurdles - Madeleine Waddell (Hamilton City Hawks)
800m - Boh Ritchie (Hamilton City Hawks)
3000m steeplechase - Catherine Lund (Ariki Athletic and Harrier Club)
High Jump - Naomi Waite (Wellington Harriers)
Discus - Suzie Kennelly (Papatoetoe AC)
Men
1500m - Jamie Mora (Whippets Running Project)
1500m - James McLeay (St Pauls Harrier & AAC)
Triple Jump - Ethan Olivier (Pakuranga AC)
Shot - Blessing Sefo (Waitakere City AC)
Javelin - Douw Botes (Papakura Athletic and Harrier Club)*
10km Race Walk - Jonah Cropp (Sumner Running Club)
* Subject to eligibility to represent New Zealand