Agronomy Degree Practice Exam

On which plant part do aphids feed?

1. Flowers

2. Leaves

3. Phloem sap

4. Roots

The correct answer is: Phloem sap

Aphids primarily feed on the phloem sap of plants. This is because they are specialized piercing-sucking insects that have developed mouthparts designed to penetrate plant tissues and access the nutrient-rich sap that flows through the phloem. This sap is composed of sugars, amino acids, and other vital nutrients, making it an excellent food source for aphids. By feeding on phloem sap, aphids not only extract essential nutrients but can also affect plant health and productivity. Their feeding can lead to stunted growth, leaf curling, and other symptoms associated with plant stress. Additionally, in the process of feeding, aphids can transmit plant viruses, complicating the impact they have on crops. While aphids may be found on various parts of the plant, such as flowers, leaves, or even roots, it is their feeding on phloem sap that defines their interaction with the plant and is crucial to their life cycle and impact on agriculture. Thus, recognizing that phloem sap is their primary food source is essential for understanding both aphid behavior and the management of these pests in agricultural systems.