Diverse Washington area corporations, in such businesses as insurance, retailing and financial services, generally are reporting continued growth in sales and profitability through the first quarter of 1979.

Details from earnings statements of various companies follow:

Bankers Security, a life insurer affiliated with International Bank of Washington, said first-quarter gains from operations were $895,468 (65 cents a share) compared with $761,567 (55 cents) a year ago.

Premium income rose 24 percent while investment income was up 15 percent. Directors voted to increase the annual dividend rate by 20 percent to 60 cents a share, starting with a semi-annual payout of 30 cents on May 18 to owners of record May 10.

U.S. Fidelity & Guaranty, a large Baltimore-based insurance firm, reported first-quarter profits from operations of $59.4 million ($2.15 a share) compared with $50.2 million ($1.84).

Manor Care, a Silver Spring operator of nursing homes, said earnings for the nine months ended Feb. 28 were $1.9 million ($1.09 a share) compared with $1.5 million (91 cents). Revenues rose 29 percent to $34.5 million. The company noted strong gains at five nursing centers that were in the process of opening a year earlier.

W. Bell & Co., a Rockville catalogue retailer, reported earnings of $1.7 million ($1.70 a share in the 40 weeks ended March 31 compared with $1.2 million ($1.22) a year earlier, as sales rose 36 percent to $60 million. In the most recent quarter, profits rose 18 percent on a 44 percent sales boost.

Heilig-Meyers Co., a Richmond based furniture and appliance retailer, reported yesterday that profits in the year ended March 31 rose to $4.4 million ($1.66 a share) from $4 million ($1.50) the previous period. Sales advanced to $70 million from $62 million.

Heck's inc., a Charleston, W. Va., retailer, reported first quarter profits of $684,000 (11 cents a share) compared with $300,600 (5 cents) a year ago. Sales rose to $74 million from $43 million.

Smithfield Foods Inc., a Virginia meat packing firm, said startup costs for newly-acquired plants and sharp increases in hog prices caused a substantial decline in first-quarter profits. Earnings were $316,000 (13 cents a share) compared with $1.7 million (67 cents) from continuing operations last year. Sales rose to $48 million from $39 million.

Dibrell Brothers Inc., a diversified manufacturer and wholesale tobacco firm in Richmond, reported first-quarter profits of $788,808 (58 cents a share) compared with $733,882 (54 cents), as sales rose to $71 million from $56 million.

Dominion Bankshares earnings in the recent quarter were $5.2 million (83 cents a share) compared with $3.8 million (60 cents) a year ago. Deposits rose 9 percent in the past year to $1.5 billion on March 31.

Commonwealth Banks Inc., of Richmond, reported a 29 percent first-quarter increase in profits to $3.7 million (70 cents a share) from $2.8 million (54 cents).

New Virginia Bancorp., a Springfield banking firm, reported an 8 percent increase in first-quarter profits to $451,432 (31 cents a share compared with $417,577 (32 cents).

D.C. National Bank posted a 77 percent gain for the first quarter. Earnings were $278,700 ($1,40 a share) compared with $156,400 (78 cents). Deposits rose 21 percent in the past year to $80.6 million on March 31.

Century National Bank, of Chevy Chase, reported first quarter earnings of $24,441 compared with a year-earlier loss of $12,091, as a nine-month trend of profitability continued for the bank, chartered in 1975. Deposits rose 28 percent in the past year to $19 million for Century, which has three offices.

Government Services Savings & Loan, of Bethesda, reported a 19 percent increase in earnings for the year ended March 31. Profits were $2.6 million ($3.05 a share) compared with $2.2 million ($2.57). Assets rose 9 percent to $324 million, deposits increased 7 percent to $282 million and loan volume was up 7 percent to $271 million. Fourth-quarter earnings dipped 3 percent, reflecting the growing pressure on S&LS of high interest rate costs.

First Financial of Virginia Corp., owner of Washington-Lee S&L, reported a 23 percent increase in earnings for the nine months ended March 31, to $1.7 million ($3.66 a share). As sets rose 24 percent in the past 12 months to $318 million.