The squad will assemble in Mount Maunganui next Tuesday for a three-day camp.
Tietjens will name his world cup line-up on June 7. The New Zealand women's side will be named on the same day.
Trial squad: Pita Ahki (North Harbour), Toby Arnold (Bay of Plenty), Kurt Baker (Taranaki), Tomasi Cama (Manawatu), Scott Curry (Manawatu), Sam Dickson (Canterbury), DJ Forbes (Counties Manukau), Bryce Heem (Tasman), Gillies Kaka (Hawke's Bay), Rocky Khan (Auckland), Fritz Lee (Counties Manukau), Tim Mikkelson (Waikato), Waisake Naholo (Taranaki), Patrick Osborne (Canterbury), Lote Raikabula (Wellington), David Raikuna (North Harbour), Trinity Spooner-Neera (Hawke's Bay), Sherwin Stowers (Counties Manukau), Belgium Tuatagaloa (Canterbury)