Correct Option: B. Fall armyworm Detailed Explanation: The Fall armyworm (Spodoptera frugiperda) is a significant pest known for its destructive impact on maize (corn) crops. This pest is particularly notorious for its ability to bore into the stalks and ears of maize plants, leading to severe damage and yield loss. Here’s a step-by-step breakdown of why the Fall armyworm is the correct answer:

1. Life Cycle and Feeding Habits:
2. The Fall armyworm undergoes a complete metamorphosis, which includes the egg, larval (caterpillar), pupal, and adult stages. The larval stage is the most damaging, as the caterpillars feed voraciously on the plant tissues.
3. They are known to feed on the leaves, but more critically, they bore into the stalks and ears of maize. This boring behavior not only damages the plant but also creates entry points for pathogens, leading to further complications.
4. Damage Mechanism:
5. When the larvae bore into the stalks, they weaken the structural integrity of the plant, making it more susceptible to lodging (falling over). This can lead to significant yield losses.
6. Damage to the ears can result in reduced grain fill and quality, making the maize less marketable and lowering the overall yield.
7. Geographical Spread:
8. The Fall armyworm is highly adaptable and has spread to various regions, including Africa and parts of Asia, where it has become a major pest of maize. Its ability to migrate and reproduce quickly contributes to its status as a significant agricultural threat.
9. Control Measures:
10. Effective management of Fall armyworm includes integrated pest management strategies such as crop rotation, the use of resistant maize varieties, and biological control methods. Chemical insecticides may also be used, but they should be applied judiciously to minimize environmental impact.

Why the Other Options Are Incorrect:

• A. Cotton bollworm:
• The cotton bollworm (Helicoverpa zea) primarily targets cotton plants, although it can also affect other crops. However, it is not specifically known for boring into maize stalks and ears like the Fall armyworm. Its feeding habits are more associated with the bolls of cotton rather than maize.
• C. Aphids:
• Aphids are small sap-sucking insects that primarily feed on the phloem of plants. While they can cause damage by weakening plants and transmitting viruses, they do not bore into the stalks or ears of maize. Their impact is more indirect, leading to stunted growth and reduced vigor rather than structural damage.
• D. Whiteflies:
• Whiteflies are also sap-sucking insects that affect a variety of crops, including vegetables and ornamentals. Similar to aphids, they do not bore into maize plants. Their feeding can lead to yellowing of leaves and the transmission of diseases, but they do not cause the type of physical damage associated with the Fall armyworm.

Revision Summary:

• The Fall armyworm is the primary pest causing significant damage to maize by boring into stalks and ears.
• Its larval stage is responsible for the most damage, weakening plants and reducing yields.
• Other pests like cotton bollworm, aphids, and whiteflies do not exhibit the same damaging behavior on maize.
• Effective management strategies are essential to control Fall armyworm populations and protect maize crops.