This article shows rapid evolution of the molecular composition of sugary nuptial gifts, and changes in mating behavior, of the German cockroach Blattella germanica, after some of its populations had evolved glucose-aversion due to anthropogenic selection pressure (insecticides in glucose-containing baits). In addition to inspecting the evolutionary change the researchers also show that there is no evidence of genetic linkage between the new courtship traits and the GA trait. Overall, the experimental set-up is great and continues nicely from previous work, paper is well written, stats simple but robust (perfectly adequate for the quite small sample sizes), and figures and supplementary materials show the multiple results clearly. And the results are exciting!

I only have minor comments that should be easy to address, but I do think they are important:

METHODS: The method section is quite hard to follow, and necessary details are often missing, or the description only comes later - for example saliva collection is explained only after experiments using it are described. Your results section is much clearer and also mentions the reasons for doing all these assays much better. Here I list a few examples of unclear bits, but I wish the methods would be overall revised to ensure they’re as coherent as the rest of the paper.

116 “video-recorded” written twice
121-122 “The pairs were video recorded for 24 hrs.” What was scored from the videos, why is it not mentioned here? Are these similar assays you write about later, at the very end of the paragraph? The whole paragraph is hard to follow, with the feeding assays explained in the middle of the mating assays.
158 “0.1 male-equivalents/µl” this measure is explained only later, please explain at first mention.
160 “(n= 10 . for each)” each what? Type of female? This section does not mention which kind of females were tested.
162-189 These sections do not mention what kind of males’ saliva is used.

DISCUSSION
The discussion is well written and very pleasant to read. However, there is too much repetion from the intro (why tell the exact same story about field crickets and flatwing mutation in 318-324?), and too little in-debt connection to other literature. How novel are your results? It’s impossible to assess, when you do not mention how many other similar findings are out there (and how those cases differ from this one), or that there are none at all.

364-378 I like the hypothesis here a lot! Are there experimental or theoretical work on other systems that would show similar dynamics? Even though your discussion here is just building hypotheses, it would be appropriate to cite at least some papers on assortative mating that discuss similar ideas – there are surely some relevant studies?

Figure 1: Is there a problem with the naming of the pairs in b&e; and c&f;, the text is the same for both panels?