Rocked by that early score from Tonga after just 3 minutes the Irish struck back with a try from Lane four minutes later followed by a penalty from out-half Gareth Steenson in the 10th minute.
Two further Bowes strikes eaach side of a brace of Steenson penalties left Ireland 26-5 up at the break.
There was to be no let up in the second half as the Irish implemented their pre-match plan of establishing control and structure.
Steenson increased their advantage with a penalty before Lane crossed for his second try in the 62nd minute by which time the outcome was well beyond doubt.
Skipper David Gannon scored try number five, which was converted by replacement Michael Glancy, deep in injury-time, having been sent clear by Man of the Match Brendan O'Connor.
Next up for the Irish is a game next Tuesday against an Argentina side who defeated Italy 43-10.
Ireland Under 21.Andrew Finn (Dolphin); Richard Lane (UCC), John Hearty (Blackrock Coll), Glen Telford (Dungannon), Tommy Bowe (Queens Uni); Gareth Steenson (Queens Uni), Tomas O'Leary (Cork Constitution); John Wickham (Clontarf), Denis Fogarty (Cork Constitution), Declan Fitzpatrick (Belfast Harlequins); David Gannon (Blackrock Coll) capt Shane O'Connor (Cork Constitution); Brendan O'Connor (Cork Constitution), David O'Brien (Old Belvedere), Jamie Heaslip (Dublin Uni).Replacements:Conor Geoghegan (UCD) for Fogarty, 67 minsKeith Doyle (UCD) for Fitzpatrick, 67 mins.Neil McComb (Dundee HSFP)for S O'Connor, 67 mins.Oisin Hennessy (Dungannon) for O'Brien, 77 mins.
Tonga: K Latu; A Fatafehi, S Kaufusi, K Tonga'uiha, P Teisina; S Taukapo, K Halapio; P Fakalelu, M Finau (capt), S Nginingini, T Fosita, S Timai, O Fifita, A Onesi, S Ofa. Replacements: V Akimeta for S Nginingini (half-time), A Lavaka for Taukapo (48 mins), N Tonga for Timai (blood, 49 -59 mins), T Folaumoetao for Finau (57 mins), T Toumohuni for Halapio (74 mins), N Tonga for Fifita, A Taufa for Teisina (both 75 mins), S Motu'apuaka for Fakalelu (79 mins).
Referee: Shinichi Isasita (Japan).
Other results: Argentina 43-10 Italy; Wales 46-11 Russia; S Africa 69-15 Scotland; N Zealand 35-13 England; Australia 25-24 France.