Comprehension : Comprehension

Q 420 / 466

UPSC CSE Prelims 2012

Chemical pesticides lose their role in sustainable agriculture if the pests evolve resistance. The evolution of pesticide resistance is simply natural selection in action. It is almost certain to occur when vast numbers of a genetically variable population are killed. One or a few individuals may be unusually resistant (perhaps because they possess an enzyme that can detoxify the pesticide). If the pesticide is applied repeatedly, each successive generation of the pest will contain a larger proportion of resistant individuals Pests typically have a high intrinsic rate of reproduction, and so few individuals in one generation may give rise to hundreds or thousands in the next, and resistance spreads very rapidly in a population.
This problem was often ignored in the past, even though the first case of DDT (dichloro diphenyltrichloroethane) resistance was reported early as 1946. There is exponential increase in the numbers of m vertebrates that have evolved resistance and in the number of pesticides against which resistance has evolved. Resistance has been recorded in every family of arthropod pests (including dipterans such as mosquitoes and house flies, as well as beetles, moths, wasps, fleas, Lice and mites) as well as well as in weeds and plant pathogens, Take the Alabama leaf-worm, a moth pest of cotton, as an example. It has developed resistance in one or more regions of the world to Aldrin, DDT, dieldrin, endrin, lindane and toxaphene.
If chemical pesticides brought nothing but, problem-if their use was intrinsically and acutely unsustainable — then they would already have fallen out of widespread use. This has not happened. Instead, their rate of production has increased rapidly. The ratio of cost of benefit for the individual agricultural producer has remained in favour of pesticide use. In the USA insecticides have been estimated to benefit the agricultural products to the tune of around $5 for every $1 spent.
Moreover, in many poorer countries, the prospect of imminent mass starvation, or of an epidemic disease, are so frightening that the social and health cost of using pesticides have to be ignored. In general, the use of pesticides is justified by objective measures such as lives saved, ‘economic efficiency of food production’’ and total food produced. In these very fundamental senses, their use may be described as sustainable. In practice, sustainability depends on continually developing new pesticides that keep at least one step ahead of the pests pesticides that are less persistent, biodegradable and more accurately targeted all the pests.
Though the problems associated with the use of chemical pesticides is known for a long time, their widespread use has not waned. Why?

EXPLANATION

Correct Option (d)

The passage attributes the continued widespread use of chemical pesticides, despite known problems, to two primary factors:

  • The favorable cost-benefit ratio for individual agricultural producers, exemplified by an estimated $5 benefit for every $1 spent in the USA.
  • In many poorer countries, the imperative to avert mass starvation or epidemic diseases compels the use of pesticides, often overriding concerns about social and health costs.

Since options (a), (b), and (c) do not accurately reflect these reasons as presented in the passage, option (d) is the correct choice.

Incorrect Options:

  • Option (a): Alternatives to chemical pesticides do not exist at all. The passage implies the existence and ongoing development of alternatives by stating that "sustainability depends on continually developing new pesticides that keep at least one step ahead of the pests pesticides that are less persistent, biodegradable and more accurately targeted all the pests." This indicates that efforts are made to find improved solutions, not that alternatives are entirely absent.

  • Option (b): New pesticides are not invented at all. This statement is directly contradicted by the passage, which explicitly mentions that "sustainability depends on continually developing new pesticides."

  • Option (c): Pesticide are biodegradable. The passage indicates that biodegradability is a desired characteristic for new pesticides ("less persistent, biodegradable"), implying that many existing pesticides may not be inherently biodegradable. The justification for their widespread use is rooted in economic efficiency and food production, not their biodegradability.