Warrington and Hull are said to have abandoned their reserve teams ahead of the new season.
With no organised reserve system in place, a handful of Super League clubs have operated with reserve teams off their own backs in recent seasons, playing glorified friendly games.
It leaves just Wigan, St Helens, Wakefield, Keighley, Leigh and Halifax in running second strings, to bridge the gap between the first team and under 19s set ups.
The Warriors have re-affirmed their commitment to a reserves set up, as reported in Wigan Today.
There were just 21 reserves games in 2017 – with Wigan playing St Helens twice, Warrington and Halifax.
There have long been calls to return to a compulsory reserves set up, which was effectively done away with several years ago by the abolition of the Under 23s competition in favour of the dual-registration system.