"Mama, look at that man," said a toddler sitting near the back of Wolf Trap's Little Theater in the Woods last Saturday morning. "Is he an angel?"

Actually, "that man" was David Troup, decked out in a Roman toga and looking vaguely biblical, singing the role of Procolo in the Children's Opera Theater production of Donizetti's "Viva la Mamma." And the child was a bit young to grasp the intracacies of this hour-long drama of back-stage intrigue in an Italian opera company.

Even with the careful explanations provided in this production, "Viva la Mamma's" blend of slapstick and bel canto probably will not mean much to children under 10, except when Mamma Agata (sung in drag and several octaves by countertenor John Ferrante) assaults the Prima Donna (Dorothy Kingston) with a large salami.

The story of "Viva la Mamma" (a catchier title than Donizetti's original "Conveniences and Inconveniences of Theatrical Life") is a familiar one of temperament and rivalry - the struggle for top billing, deference and attention.

Halfway through the rehearsal of an imaginary opera seria, "Romulus and Ersilia," the Prima Donna insists that the name of the opera be changed to "Ersilia and Romulus." The tenor (David Richie) threatens to go back to Russia, and the mezzo soprano (Patricia Boyd) walks out, giving Mamma Lucia a chance to step into the role of Romulus.

Procolo, the Prima Donna's father, sets the tone at one point when he tells the cast: "Everybody rise; the name of my daughter is about to be spoken." But he is no match for Mamma, who pointedly tells the Prima Donna: "Last week at La Scala, you sang in the chorus."

Like Procolo, Mamma has a daughter, Luiga (Ann Barzola), whose career she is pushing - but it is an uphill push. Luiga, singing the bit role of a messenger, has a single line at the end of "Romulus": "Romulus, do not strike; Jupiter has spoken." But after singing it and running offstage, she comes back to solicit applause, carrying flowers which she throws into the audience.

Amid all these plot complications (and some broad parody of the conventions of opera seria), "Viva la Mamma" manages to include some exquisite solo and ensemble numbers, a comic showpiece in which Ferrante does imitations of violins, oboes, cellos and trumpets, and a spiteful duet between Mamma and the Prima Donna ("Oh, how I detest you." "May roaches infest you.") which ends with Mamma threatening the Prima Donna with a pie.