Question

The larvae of mosquitoes die when oil is spread on the water. Why does it happen? Give a proper reason.​

Answer 1

When oil is spread on the surface of water, it blocks mosquito larvae from breathing air and prevents oxygen from dissolving into the water, resulting in the larvae's death. This method is outdated, and modern alternatives include genetically modified mosquitoes and larvivorous fishes.

Step-by-step explanation:

The larval stages of mosquitoes need to breathe air at the surface of the water to survive. When oil is spread on the surface of the water, it forms a thin layer that prevents oxygen from dissolving into the water and also blocks the larvae from reaching the air. This suffocates the larvae and leads to their death. The use of oil is an old mosquito control method, but it has been largely replaced by more sustainable and environmentally friendly alternatives, such as the introduction of larvivorous fishes or the use of genetically modified mosquitoes.

Recent technological advances have allowed for the creation of genetically modified mosquitoes that produce female offspring dying at the larval stage, which helps to reduce the mosquito population and the spread of mosquito-borne diseases. Other historical methods for reducing mosquito populations have included drainage of wetlands for farmland and the manipulation of water levels in lakes.

Answer 2

The thin layer of oil on top of the water prevents mosquito breeding in two ways: mosquito larvae in the water cannot penetrate the oil film with their breathing tube,and so drown and die; also adult mosquitoes do not lay eggs on the oiled water