Hektar

Description

• Appearance:

  • Adults are small, measuring 1–1.5 mm in length, with wings covered in a white, waxy substance that gives them a powdery look.
  • The larvae are tiny, flat, and yellowish-green, attaching themselves to the underside of leaves.

• Life cycle:

  • Eggs are laid on the underside of leaves.
  • Larvae hatch from the eggs and feed on plant sap.
  • Multiple generations occur annually, especially in greenhouses, where warm temperatures and high humidity accelerate their lifecycle.

Damage Caused

1. Direct feeding:

   • The whitefly pierces leaves to feed on sap, weakening the plant.
   • Affected leaves turn yellow, wilt, and in severe cases, fall off.

2. Honeydew production:

   • Whiteflies excrete a sugary substance called honeydew, which promotes the growth of sooty mold – a black fungal layer on leaves.
   • Sooty mold reduces photosynthesis and the commercial value of plants.

3. Transmission of viruses:

   • Whiteflies are vectors for numerous viral diseases, such as tomato mosaic virus or cucumber mosaic virus, which complicate treatment and increase economic losses.

Host Plants

• Preferred crops include:
  • Tomatoes
  • Peppers
  • Cucumbers
  • Eggplants
  • Ornamental plants (e.g., begonias, chrysanthemums, gerberas).

Control Measures

1. Preventive methods:

   • Use of insect-proof nets to protect greenhouses.
   • Sanitation by cleaning greenhouses and removing plant debris after harvest.
   • Crop rotation and avoiding prolonged monoculture.

2. Biological methods:

   • Introducing natural predators like Encarsia formosa or Macrolophus pygmaeus, which feed on whiteflies.
   • Using entomopathogenic fungi such as Beauveria bassiana.

3. Chemical methods:

   • Application of systemic or contact insecticides (e.g., based on acetamiprid, imidacloprid, or spinosad).
   • Alternating active substances to prevent whitefly resistance to pesticides.

4. Traps and auxiliary techniques:

   • Yellow sticky traps to attract and capture adult whiteflies.
   • Adjusting ventilation and humidity to make the environment less favorable for whitefly development.