Two-term Fairfax County Supervisor Marie B. Travesky was ousted yesterday by conservative Republican Elaine N. McConnell in a bitter primary for the Springfield seat on the county board.

McConnell, owner of a private school, won the GOP nomination by a margin of 126 votes in a light voter turnout.

Prince William County voters also defeated a two-term county supervisor, picking Democrat John E. Bonfadini of Manassas, a professor at George Mason University, to replace Donald L. White, an accountant, as the Gainesville member of the county board. Bonfadini, a former legislative candidate, won his primary by a margin of 106 votes.

Travesky, who has represented the Springfield area since 1976, blamed her defeat on County Board Chairman John F. Herrity and other conservatives. "It was the New Right, absolutely," she said last night. "It was Jack Herrity. It was Gun Owners of America director Larry Pratt. It was former GOP county chairman Joe Ragan. There's no two ways about it."

Herrity, who represented the Springfield area before winning his countywide position, could not be reached for comment. He had said previously he was not taking sides in the primary.

"Travesky is not out of politics," she said last night. "One defeat by the New Right does not throw good people out of politics." She said she was examining "several options," but declined to elaborate.

"We can't believe this," McConnell said after her victory. "I'm so surprised and overwhelmed."

McConnell will face Democrat pharmacist Gerry Serody in the Nov. 8 elections. He defeated his opponent Thomas E. Giska by 244 votes in a Democratic primary.

Another conservative Fairfax Republican, Gwendalyn F. Cody, who is seeking to return to the General Assembly also was victorious yesterday, beating moderate Republican Lynne Purvis by 566 votes in a contest for the 38th District House seat. Cody held the Annandale seat until last November when she was defeated by Democrat Del. Nora A. Squyres, whom she will face again in the fall.

The Cody-Purvis race apparently generated the most voter interest in Fairfax, with a voter turnout of 12 percent. Countywide, 15,035 individuals or 8.92 percent of Fairfax County's 168,592 registered voters cast their ballots.

Democrat Emilie F. Miller, a legislative aide to state Sen. Adelard L. Brault, won her battle against Daniel S. Alcorn for the party's nomination for Brault's 34th District Senate seat. Brault, dean of the Northern Virginia delegation in Richmond, is retiring after 18 years in the legislature.

Fairfax City Mayor John W. Russell easily defeated two GOP opponents to win his party's nomination for the Brault seat.

In the crowded 42nd District House race to fill the seat of another retiring Fairfax legislator, Republican Robert K. Cunningham, a retired Army officer, and Democrat Lawrence J. Pascal, a lawyer, emerged victorious. They will face each other in November to replace Del. Warren E. Barry of Springfield, a Republican who is running for clerk of Fairfax County Circuit Court.

In a close race, Lonnie B. Bridges apparently beat Daniel K. Moller by seven votes, for the Republican nomination for the 33rd District Senate seat, held by Democratic Sen. Charles L. Waddell of Sterling. Waddell, an airlines employe, is seeking reelection in the district, which covers part of Fairfax and Loudoun County.

Voters in both Prince William and Loudoun counties picked nominees for the office of sheriff in countywide balloting. In Prince William, Republican Harry Hittle and Democrat Wilson Carlin Garrison Jr. won the right to face each other in November for the right to succeed Carl A. Rollins Jr., who is retiring after 24 years.

John R. Isom, a captain in the Fairfax Police Department, won a three-way race for the Democratic nomination for Loudoun County sheriff by a comfortable margin. Isom will face Republican Leonard W. McDonald for the position that has been held by Don Lacy, a Republican whose tenure has been marked by scandal and controversy. Lacy did not seek reelection.

Incumbent John T. Keyes won the nomination for a fourth term as Loudoun's revenue commissioner, easily defeating challenger John S. Witul.

Ann B. Kavanagh won the Democratic nomination for the Dulles District seat on the Loudoun County Board of Supervisors.

Public housing critic Stephen A. Armstrong defeated John D. Austin for the Republican nomination for the Providence District seat on the Fairfax County Board of Supervisors. Armstrong, who won by a 316 vote margin, will face incumbent Democratic James M. Scott and Independent William M. Lockwood in the fall.

Democrat Philip L. Chabot Jr. defeated Louis K. Rothberg, winning the opportunity to challenge Republican Del. Frank Medico for the 44th District House seat in the Mount Vernon area of Fairfax.

Guy A. Guiffre, an accountant, won a four-way race for the Republican nomination for the Gainesville seat on the Prince William Board of Supervisors. He will face Bonfadini in the fall.

Incumbent John D. Jenkins defeated Edward G. Rodriguez for the Democratic nomination for the Neabsco seat on the Prince William board.

Yesterday's primaries were held to select Republican and Democratic nominees for seats in the Virginia General Assembly and for local elective offices in which party nominees were not selected by party conventions or mass meetings. None of the 27 members of the Northern Virginia delegation to the General Assembly faced primary challenges.