Communities have attempted to control the size of mosquito populations to prevent the spread of certain diseases such as malaria and encephalitis. Which control method is most likely to cause the least ecological damage?

4) increasing populations of native fish that feed on mosquito larvae in the swamps

Explanation:

The complete question is:

Communities have attempted to control the size of mosquito populations to prevent the spread of certain diseases such as malaria and encephalitis. Which control method is most likely to cause the least ecological damage?

1) draining the swamps where mosquitoes breed

2) spraying swamps with chemical pesticides to kill mosquitoes

3) spraying oil over swamps to suffocate mosquito larvae

4) increasing populations of native fish that feed on mosquito larvae in the swamps

The method by which the pests or the insects' are controlled by introducing their natural enemy in the environment to reduce their number is termed as biological control. The natural enemy can either be a predator, a parasite, a herbivore or any other organism that leads to a reduction in the number of the target organism. The advantage of using this method is that it circumvents the need to use artificial chemicals that cause harm to the environment as well as the other living organisms. In the given options, increasing the populations of native fish are the predators of mosquito larvae is an example of biological control and hence is the best option.