There isn't one. By the literal meaning, it would be "dog", which used to be a common insult, if literature is any guide, but which has fallen out of use. "Bitch" implies malice and viciousness, shallow in thought but deeply ingrained. And, of course, it implies unwomanliness, and it doesn't make sense to accuse a man of unwomanliness.
The disturbing thing with insults is that even today, they're mostly used in gender-specific ways. Even the ones that don't seem gender-specific, such as "jerk", are rarely applied to women. That's sexism in itself -- when we want to insult a woman, instead of reaching for a word that communicates exactly what we feel, we fall back on the generic "bitch" because her gender seems to have something to do with her transgression. There are so many words to choose from that communicate exactly what's wrong with someone: jerk, liar, pig, dumbass, worm, bastard, loudmouth, traitor. It should feel just as right and satisfying to apply them to a woman as to a man. But in the heat of the moment, your aggression amplifies every negative feeling, including your sexism, and you watch to lash out at that bitch. Better control yourself, though. When you call someone a "bitch", it sounds like you think what they've done was inappropriate for a woman. I.e., maybe it would have been fine if she was a man. Now you've got everyone wondering how you feel about women instead of thinking about what she's done to earn your enmity.
So next time you want to lash out verbally at a woman, choose your words carefully. Is she an idiot? A jerk? A dick? (Hmmm, maybe there's a better word for that.) Let's let "bitch" go the way of "harpy" and "harridan". When you hear those words, you don't really trust them, because they give away the fact that the speaker is holding their target to a sexist standard of femininity. Somehow "bitch" survived as our only remaining insult for women (except "whore", "slut", and all the other words that mean "woman who makes me feel bad by having sex with men who aren't me".) Well, there's "cunt", but that's mostly a Briticism, and it's just as lazy and meaningless as "bitch".
There are so many ways to give your listener a vivid image of your target instead of have them wondering about your misogyny. You could call someone mealy-mouthed, two-faced, greedy, ruthless, petty, malicious, mercenary, or disloyal. (When a woman's sexual behavior disturbs you, try "dishonest": if that doesn't apply, then she probably isn't doing anything wrong.)
Not only will you seem much more composed, serious, and credible than if you resorted to "bitch", not only will you leave your listeners with a more vivid and convincing image of your target, it's also much more efficient, since you'll be using the same store of insults for both men and women. And as hackers we should always be using the most abstract solution.
(Of course, if you really want it to hurt, then sexism never hurts. Or rather, it always hurts. But when you're playing to an audience, malice undermines your credibility.)
