** MLPs tumble on heavy volume amid carnage in energy stocksas oil prices plummet to 7-year lows
** Benchmark Alerian MLP index plunges 6.2 pct, itsworst one-day plunge since the S&P's downgrade of U.S. debt inAug 2011
** Worst performer Legacy Reserves drops a fifth asStifel cuts its rating to "hold"
** Targa Resources, Energy Transfer Equity,Plains All American, Williams Partners careen10-15 pct
** However, some Marcellus-Utica shale-focused MLPs hold upbetter: Antero Resource Midstream falls 1.4 pct, EQTMidstream slides 2.2 pct and Columbia Pipeline Group drops 4.5 pct
** Those with strong parents also outperform with RoyalDutch Shell affiliate Shell Midstream downjust 1.3 pct and Phillips 66 Partners lower by 2.5 pct
** Alerian index now down 45 pct YTD to a 6-year low
** Other yield payers, such as REITs and utilities, alsounder pressure with a near certain Fed rate hike looming nextweek
(RM: lance.tupper.tr.com@reuters.net)