CBSE Class 10 Answered
Insecticides are chemicals used to destroy insect population in a field. If a large amount of insects are blown with wind from a nearby field, its immediate effect would be destruction of the insects in the given food web. Therefore, the population of insects such as flies and caterpillars would be reduced. In the absence of flies and caterpillars, the sparrows would have no food to eat and their population would get reduced. Consequently, the population of hawks which directly feed on sparrows would also be reduced. On the other hand, snakes will continue to obtain food till the frog population exists in the food web. However, in the absence of flies, the frog population would also reduce, thereby reducing the population of snakes as well. Therefore, although the population of hawks and snakes would eventually diminish, the reduction in the number of hawks would be much greater ad faster than the reduction the number of snakes.
If any of the animal population gets reduced in the food web, its immediate effect would be the decline in the population of the animals which directly feed on this population. Consequently, the entire food web gets disturbed, thereby disturbing the balance in nature.
Since, the sparrows directly feed on the insects, the population of sparrows would be the most affected in this case.