Complex sentence: It is not clear why the inhibitory compound is detected, as it does not seem to be produced by females, but scientists speculate that its presence in the female pheromone blend may be too small to be detected by scientific equipment.
Split into simpler sentences: It is not clear why the inhibitory compound is detected, as it does not seem to be produced by females. One possibility is that its presence in the female pheromone blend may be too small to be detected by scientific equipment.