Counteracting Perverse Incentive effects in 1902 Hanoi rat population

A perverse incentive is a reward system that has the opposite effect to the one intended.

In Hanoi, under French colonial rule, a program paying people a bounty for each rat tail handed in was intended to exterminate rats. Instead, it led to the farming of rats. https://en.wikipedia.org/wiki/Perverse_incentive

Question

Given our current knowledge of Game Theory, Biology, Population Dynamics and other relevant sciences: what would have been the most effective way to persuade the people of Hanoi to exterminate rats in a low-tech society in 1902.

Note: To prevent this being a mere matter of opinion or crazy ideas, I have added the hard science tag. Thus I'd like informed opinion on things like population dynamics and historical evidence of successes in wiping out 'vermin'.

World-building Context

Depending on the answers to this question, I may go on to ask other questions that will require plausible replies to the the above, for example:

Is there any way of measuring the effects on history, if rats had been wiped out worldwide in the early 20th century? What would the world look like without them?

Please don't answer this question but bear in mind they are my reason for asking. Many thanks.

posted about 5 years ago

chasly from UK‭

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