This insect is known in Sri Lanka by various names such as powdery mildew, whitefly and white bug. About 1 mm in length, this pest lives in herds sucking the sap of various plants. In addition to coconut, the insect attacks plants such as bitter gourd, watermelon and snake gourd etc, belong to Cucurbitaceae and peanut, cowpea and beans etc, belong to Leguminosae also being affected. In addition, it acts as a carrier of viruses or fungi and causes huge damage. At higher temperatures, their activity is somewhat stronger.
This white color insect penetrates the leaflets of coconut seedlings and mature coconut trees and then damages the coconut plant by sucking the sap out of them. They belong to the phylum Arthropoda class and have four basic stages in the life cycle. On the underside of the leaves of the coconut tree we can see with the naked eye many stages of the life cycle of this insect.
Eggs are small, oval, smooth and color varies from yellow to brown. Females lay about 30-40 eggs at one time. This stage usually appears in a spiral pattern on the underside of the leaf and the eggs are covered with a wax-like coating.
A stage with a body size similar to that of an egg with some legs. This stage is called “crawler’s”. At this stage, they begin to absorb nutrients from the leaf tissue of the host plant.
It is the stage when the body is well modified to absorb sap from the plant. This stage is when the nutrients are initially absorbed by the body of plant tissue and then stop feeding to organize internal structures remodeling to become an adult.
This stage, which takes the form of a small white moth, produces a fine dust or wax-like secretion that surrounds the body. They are most active in the morning. These adult insects, which live in groups, are widely spread by the wind. Sucking on the leaves of the host plant is done in the same way as in the other stages of its life mentioned above. Whiteflies excrete excess fluid as a result of metabolism and deposit as a honeydew-like sticky solution on the surface of lower branches of the coconut tree. Due to this, the plant leaflets are also susceptible to black fungus (Sooty mold appearance). This is a secondary infection caused by the whitefly menace.
Symptoms of damage
- White waxy substance on the underside of the leaves of the coconut tree.
- Symptoms of chlorosis of the leaves (loss of green color of the leaves) appear and after the onset of the symptoms the irregular yellowing of the leaf tissue.
- A sticky honey-like solution (honeydew) is deposited on the surface of the lower branches of the tree.
- Occasionally black fungus (sooty mold), appearing on the leaf surface of lower branches.
- Leaf shedding in case of severe damage.
- Decreased productivity.
- Manual removal.
- Apply pressurized water to wash away the underside of the leaves well.
- Farmers can Wrap greased, yellow polythene covers around the trunk of the coconut tree to attract and repel larvae.
- Fumigation in cultivated areas. Use leaves like Neem (Margosa) and Holy Basil/ Sacred Basil (Madhuruthala) here.
- 01st method
Dissolve 3g of Thiamethoxam or 20ml of carbosulfan in 10 liters of water and prepare the mixture. Then spray thoroughly the underside of the leaves of the plant making them wet.
- 02nd method
- Chlorantraniliprole and Thiamethoxam
Dissolve 2.5 g of an insecticide containing chlorantraniliprole and thiamethoxam in 10 liters of water to prepare the mixture. Then spray thoroughly the underside of the leaves of the plant making them wet.
- 03nd method
- Neem oil & soap mixture
Water – 1 l
Soap powder – 5 g
Neem oil – 10 ml