No, as it's possible her and her kind could potentially help you in ME3.
I would say no but there may be consequences in Mass effect 3. When you save her, she tells you both in Mass effect 1 & 2 that she is there in the final battle. How ever, with the history of Rachn, Krogans and Salarians, it may have issues however, I'm guess with enough paragon or renegade, you can make it :3
There is a line in ME2 that Shepard him/herself said: "Refusing an ally can BITE YOU IN THE ASS" That's why i think it's better to let the rachni queen live, as well as rewriting the geth in ME2, when i face choices about killing a potential ally I always choose paragon.
Well, you'd kill a potential ally. On the bright side, there would probably be no rachni husks.
I hope the rachni don't betray you. I mean you spared their life. They should return the favor. -TOMCAT1025
Now... I'm not 100% sure about this but... I think the rachni husks still show up even if you killed the queen. At least, that is what I'm hearing on some of the sites. Turkeysocks
I've heard that the Rachni Queen, if allowed to survive to ME3, may suffer the same fate as her mother. If this is the case, then the rachni may wind up enemies in ME3. Now this is nowhere near certain, but it's worth remembering that the Rachni are not guaranteed to be your allies in ME3. In the end, it really comes down to whether you think the Rachni will help you or harm you in ME3
I would say you should. Anish
I think you should save her cause they will help in ME3 which also it pretty much said in the first two games that the rachni are not aggressive and that they were indoctrinated to fight the war. So I think it be cool if they became apart of the galactic community after ME3. Also what everyone else said about lossing and potential ally.
The best is probably to play twice : with one character who will kill the Rachni Quenn, and one who won't. That's what I did : half of my characters let her live while the others killed her. Dracian ME