The rural people living in different parts of Sri Lanka misunderstand this insect damage caused by the powdery mildew and white bug.. etc. You should know that the “coconut whitefly” causes this damage. 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.

Egg stage:

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.

Larval stage:

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.

Pupae stage:

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.

Adult stage:

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.
  
  
  

Control

• 02^nd 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.

• 03^nd method

• Neem oil & soap mixture

Material required

Water – 1 l
Soap powder – 5 g
Neem oil – 10 ml

Take the above ingredients and mix well. Then spray the underside of the plant leaves thoroughly, making them wet. Spray this solution every two weeks for about two months.