Question

Consider a farm planted with corn being infested with caterpillars. During the first pesticide application out of twenty (20) caterpillars sprayed, only five (5) were killed. After some times, the fifteen (15) individuals that survived grew in number to about thirty (30) individuals. Another application was done and about twenty-five (25) individuals were killed.

i. What is the pest and the type of pesticide used by farmer?

ii. Does the pest of corn exhibit pesticide resistance?Justify your answer.

iii. List the stages of pesticide resistance described in the paragraph. (NOTE: Write only the stage reflected in the paragraph.)

Answer 1

i.

FACTS:

• Ast it is given that the pest was a caterpillar, therefore it rules out the other pests and now we can have four options which are caterpillar pests. These are corn earworm, corn borer, fall armyworm, and stalk borer. Therefore the pest would be one of these.
• As corn earworm is the most common caterpillar corn pest found in the USA, therefore, it may be a corn earworm, that is, Helicoverpa zea.
• It is also one major agricultural pest. It is called are corn earworm because it is infamous for huge destructions of the cornfields. Three stages of its life cycle are egg, larva, and fully grown adult.

Now based on the above facts, the answer to the question will be as follows:

• Pest: Helicoverpa zea
• Type of pesticide: Farmer would have used the following pesticides for the caterpillar stage of the pest.

1. For the first pesticide application- it may be Beneficial nematodes to control larvae for the first application.
2. After it, when the pests persisted, farmer should have applied Bacillus thuringiensis as a pesticide to kill them all.

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ii.

Does the pest exhibit pesticide resistance?

• Yes, it does show some pesticide resistance, which is why only 5 were willed in the first application. It not only survived but it also reproduced successfully to double its number from 15 to 30 in some time before the second pesticide application. This is proof of resistance.

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iii.

List of stages of pesticide resistance described. Write only the stages reflected in the paragraph.

• Stages of Pesticide resistance:

1. After first pesticide application, out of 20 caterpillars, only 5 got killed and 15 survived.
2. The surviving 15 caterpillars grew in number to 30 individuals, that is, double in number.
3. The second application of pesticides killed 25 individuals, but 5 still survived it.

Above are the stages reflected in the paragraph which are clear evidence of pesticide resistance.

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