Aedes typically prefers small artificial containers for breeding. They do not breed in ponds or pools of water.
From experiments in the lab we know that a single mosquito can effectively contaminate water bodies of 5 Liters (1.3 gallon). Pyriproxyfen dissolves in the water and is effective in concentrations of just 10 parts per billion.
In the field, there will also be accumulation of pyriproxyfen from multiple contaminated mosquitoes over time. Aedes prefer breeding sites where mosquito larvae are present (that emit a specific smell) so you will have several mosquitoes visiting the same breeding source and spreading pyriproxyfen. From field studies in the Caribbean we learned that even large rain barrels could be effectively treated, probably due to this accumulation effect from multiple mosquito visits.