(Adds details; updates prices) Jan 13 (Reuters) - Canada’s main stock index reversed course to trade lower on Wednesday, dragged down by weakness in energy stocks, while a drop in convenience-store operator Alimentation Couche-Tard Inc on merger reports further dented sentiment. * The energy sector dropped 1.1% as U.S. crude prices were down 0.8% a barrel, while Brent crude lost 1%. * Alimentation Couche-Tard fell 7.4%, the most on the TSX, after the company submitted a non-binding offer letter to buy European retail giant Carrefour at a price of 20 euros per share. * At 9:43 a.m. ET (14:43 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was down 26.34 points, or 0.15%, at 17,959.46. * Meanwhile, Ontario on Tuesday declared an emergency after latest modeling put Canada’s most populous province on track to have more than 20,000 new COVID-19 cases per day by the middle of February. * The second biggest decliner was commodity chemicals maker Methanex Corp, down 3%. * Adding to the downbeat mood, the materials sector , which includes precious and base metals miners and fertilizer companies, lost 0.1%. * On the TSX, 93 issues were higher, while 120 issues declined for a 1.29-to-1 ratio to the downside, with 21.04 million shares traded. * The largest percentage gainers on the TSX were pot producer Cronos Group Inc, which jumped 3.7%, and cancer drug developer Trillium Therapeutics Inc , which rose 3.3%. * The most-heavily traded shares by volume were Toronto-Dominion Bank, Alimentation Couche-Tard and Northern Dynasty Minerals Ltd. * The TSX posted six new 52-week highs and no new lows. * Across all Canadian issues there were 44 new 52-week highs and two new lows, with total volume of 43.31 million shares. (Reporting by Amal S in Bengaluru; Editing by Krishna Chandra Eluri)