Two insect groups vary genetically by two genes. when put together, they were able to reproduce and produce offspring that could also breed. which best describes this insect population?

The answer is The insects are the same species.

Species is a group of similar organisms able to reproduce (to exchange genes and interbreed) only within the group. That means that organisms from different species could not exchange genes. Since mentioned insect groups are able to reproduce and produce offspring that could also breed, these groups belong to the same species. If they could not reproduce and  produce offspring that could also breed, these groups would belong to the different species.