Aphis

Aphis citricola1

Aphis fabae STEREO, 0050x

Aphis.sambuci

Aphids on Helleborus niger

Aphis.sambuci.colony

Aphis is a genus of small sap-sucking insects belonging to the family Aphididae. Members of this genus are commonly known as aphids or greenflies, although the coloration among the species can vary widely. Aphis species are among the most prominent and economically significant pests on cultivated plants in temperate regions. They are capable of causing extensive damage to a wide range of host plants by feeding on the sap and spreading various plant viruses. Due to their rapid reproduction rate and the wide array of plants they can infest, Aphis species are a major concern in agriculture and horticulture.

Description

Aphis species are small, usually less than 3 mm in length, and often green in color, although some species may be yellow, black, or brown. They have soft, pear-shaped bodies with long, slender mouthparts adapted for piercing plant tissues and sucking out the sap. Aphids have two short tubes, called cornicles, projecting backward from the end of their abdomens. These cornicles secrete a waxy substance that deters predators.

Life Cycle

The life cycle of Aphis species can be quite complex, involving both sexual and asexual reproduction, and in many cases, alternating between two different host plants. Most species produce several generations a year. In spring and summer, females reproduce parthenogenetically, giving birth to live young without mating. These offspring are usually all female and can themselves reproduce parthenogenetically. In the fall, as temperatures drop and day length decreases, Aphis species may produce males and sexual females that mate to produce eggs. The eggs overwinter and hatch into females the following spring, starting the cycle over again.

Ecological Impact

Aphis species play a significant role in their ecosystems. They are a key food source for a variety of predators, including ladybugs, lacewings, and hoverflies. However, their feeding habits can cause significant damage to plants, including stunted growth, yellowed leaves, and decreased yields. Some species also produce a sticky substance known as honeydew, which can lead to the growth of sooty mold on the plants.

Economic Importance

Due to their ability to spread plant viruses and cause feeding damage, Aphis species are considered major pests in agriculture and horticulture. They can infest a wide range of crops, including fruits, vegetables, and ornamental plants. Control methods include the use of insecticides, biological control agents such as parasitoid wasps, and cultural practices such as crop rotation and the removal of infested plants.

Species

There are several hundred species within the genus Aphis, including:

• Aphis fabae (Black bean aphid)
• Aphis gossypii (Cotton aphid)
• Aphis pomi (Green apple aphid)
• Aphis craccivora (Cowpea aphid)

See Also

• Aphididae
• Pest
• Biological pest control
• Integrated pest management