Citrus cottony scale

The citrus cottony scale (Pulvinaria aurantii) is a significant insect pest belonging to the family Coccidae. It is widely recognized as a serious threat to citrus orchards in various subtropical and tropical regions globally, causing direct physiological stress to the host plants.

This pest primary infests citrus species, including lemons, oranges, and mandarins. However, it can also be found on other broad-leaved evergreen trees and ornamental shrubs. By feeding on the sap, the insects weaken the plant structure and stunt the development of new vegetative growth.

The life cycle involves an egg stage, several nymphal instars, and the adult stage. Adult females produce prominent, white, cottony ovisacs (egg masses) that are easily identifiable on the twigs and leaves. The nymphs, often called crawlers, are the primary stage for migration and dispersal across the plant canopy.

The damage caused by Pulvinaria aurantii is two-fold: direct feeding damage and indirect secondary effects. Direct feeding results in leaf yellowing, twig dieback, and reduced fruit quality. Indirectly, the copious production of honeydew promotes the growth of sooty mold, which inhibits photosynthesis and necessitates costly washing of fruit post-harvest.

Integrated pest management (IPM) is essential for effective control. Strategies include:

• Regular monitoring for the presence of crawlers during peak spring and summer activity.
• Application of systemic insecticides or horticultural oils to target vulnerable life stages.
• Pruning and destroying heavily infested branches to reduce local population density.
• Encouraging the presence of biological control agents, such as parasitoid wasps and ladybird beetles.