This was honestly an illuminating chapter, for how seemingly brief it was in terms of actual events playing out.
Reika's possessiveness and need for connection was always present, and she initially had latched onto Ayumi. She did love Ayumi, in a capacity, but it was that fear of being left behind that won out - so if the Insect amplifies the core "self" of the host, Reika becoming a zealot following her Queen with such ferver kind of makes sense.
She was "abandoned" in her mind by Ayumi at a pivotal moment of stress, Awakened, and her Insect's allegiance to Towa meant that all that possessiveness and desire for connection to someone who would make her stronger transferred over - and her frustrations at and hurt over Ayumi amplified in turn, becoming malice and contempt.
I fully believe Reika's not dead here - though it's probably akin to "ego death" or something (mentioned in previous chapter discussion posts, I believe), wherein her Insect has been ... I guess maybe put in stasis? If so, possibly to prevent it from consuming Reika any further. And then Ayumi will Dye Reika into her own Brood, and the healing process would begin from there.
No clue what happens to Reika at that point; if there's any of "her" left in there, it might be mere fragments, depending on how much of the Insect consumed of her. Clearly enough to recognize Ayumi, but that's not really saying anything.
I did initially take "resolution" to mean of the arc and not the story - I feel like the word would be "Conclusion" at that point. I'm very much hoping I'm correct, because there is so much more to be done here, even if we never see humanity successfully drive back the Bug Apocalypse.
But as weirdly tense and "inconclusive" as this chapter was, I think I like the direction it went, as far as solidifying Reika and Ayumi's situation a bit more and setting up whatever transpires for them next (vague as it may be).
Thanks for the continued TL work on this series. I very much hope there's many months more in store.