The cotton aphid, also known as Aphis gossypii, is a small insect belonging to the Aphididae family. India’s cotton is a major cash crop vulnerable to insect attacks at all stages of its growth. Among the sucking pests, cotton aphids pose a significant threat due to their ability to damage the cotton plant’s leaves, stems, and buds, leading to reduced growth and yield. It feeds on the plant’s sap, which can cause the affected leaves’ yellowing, curling, and stunted growth.
In addition, they excrete a sticky, sugary substance known as honeydew that attracts fungi, which can further harm the plant by causing black sooty mold to form on the branches and leaves. This mold can reduce the plant’s photosynthetic ability and lower the quality of the cotton fibers. Cotton aphids can also transmit plant viruses, making them a significant threat to cotton production.
Aphid management in Cotton
The life cycle of Cotton Aphid
The life cycle of the cotton aphid (Aphis gossypii) includes the following stages: egg, nymph, and adult.
- Egg: Female cotton aphids reproduce asexually and give birth to live young without mating. Some females may lay eggs for overwintering, which hatch into nymphs in the spring.
- Nymph: The nymphs that hatch from eggs or are born directly from a female resemble adult cotton aphids in appearance but are smaller and lack wings. They feed on the sap of cotton plants, molt several times as they grow, and eventually mature into adults.
- Adult: Upon reaching maturity, cotton aphids are fully-formed, winged insects that can fly and spread to new plants. They continue to feed on the sap of cotton plants and reproduce asexually, giving birth to live young.
The high reproductive rate of cotton aphids and their ability to damage cotton plants and transmit viruses make them a significant threat to cotton production.
Identification of the Cotton Aphid
Cotton aphids (Aphis gossypii) are little, soft-bodied insects that live on the undersides of leaves. The nymphs are yellowish or greenish brown in hue, whereas the adults are slightly bigger and greenish brown. When the cotton aphid population grows too thick, and there is a need to colonize new plants, winged variants of the cotton aphid may arise. Aphid insects feed on plant sap and can harm cotton crops by lowering yields and quality.
Symptoms of damage by Cotton Aphid
- Manifestation of the damage
- Infesting the young, tender shoots as well as the undersides of the leaves
- The wrinkling and curling of the leaves
- The growth that is stunted
- The look of being blighted when the infestation is severe
- The dark color of the plant is caused by the development of black sooty mold, which is caused by the excretion of honeydew.
Impact/ Favorable conditions for Cotton Aphid growth in Cotton crop
Cotton Aphids can cause significant yield loss if their populations are not controlled in time. If more than 90% of plants are infested for 2-3 weeks, it can result in a substantial loss of yield. Dry and warm conditions are ideal for their development. They often gather in bunches and feed on the undersides of well-fed young leaves and stem tips. They puncture sensitive plant tissues with their long mouthparts and suck out juices.
Farmers should look at the estimated yield loss, the cost of control, and the price of cotton to decide if they ne