(Adds details on sectors and stocks, updates prices)
* TSX fell 78.04 points, or 0.56 percent, to 13,873.41
* Six of the TSX's 10 main groups were lower
TORONTO, May 2 (Reuters) - Canada's main stock index fell on Monday as lower oil prices weighed on energy stocks, offsetting a jump in the shares of Manitoba Telecom Services Inc on news of the company's acquisition by BCE Inc.
The most influential movers on the index included Suncor Energy Inc, which fell 2.4 percent to C$35.94, and Canadian Natural Resources Ltd, which declined 1.5 percent to C$37.10.
The overall energy group retreated 1.8 percent.
Crude prices fell as data showing higher Middle East oil production and record hedge fund buying sparked profit-taking on last month's outsized rally. U.S. crude prices were down 1.4 percent at $45.29 a barrel.
Gold stocks retreated as gold eased back below $1,300 after having made a fresh 15-month peak.
Goldcorp Inc fell 2.1 percent to C$24.74, while Barrick Gold Corp was down 0.5 percent at C$24.16.
Valeant Pharmaceuticals International Inc fell more than 10 percent to C$37.59, while the overall healthcare group was down 3.4 percent.
The financials group fell 0.5 percent.
At 10:56 a.m. EDT (1456 GMT), the Toronto Stock Exchange's S&P/TSX composite index fell 78.04 points, or 0.56 percent, to 13,873.41. Six of the index's 10 main groups were lower.
The index ended 3.4 percent higher for the month of April, and has rebounded 20 percent from an almost 3-1/2-year low in January, though it has been unable to climb back above 14,000.
Telecom and media company BCE Inc said it would buy Manitoba Telecom Services Inc for about C$3.1 billion to expand in the western Canadian province. Manitoba Telecom jumped 15.7 percent to C$38.00, while BCE was up 0.2 percent at C$58.97.
The overall telecoms group rose 4.2 percent.
Shares of Air Canada rose 5.4 percent to C$9.83. It follows a 12.7 percent advance on Friday after the company reported a first-quarter profit compared with a loss a year earlier, helped by a decline in fuel costs. (Reporting by Fergal Smith; Editing by Bernadette Baum)