Oleander scale

The oleander scale (Aspidiotus nerii) is a prominent member of the family Diaspididae, falling under the order Hemiptera. It is a highly polyphagous pest, widely distributed across subtropical and tropical regions, and frequently encountered in greenhouses worldwide, where it poses a significant threat to various plant species.

This scale insect commonly attacks a diverse array of hosts including citrus trees, oleander, olive, palms, ivy, and various succulent species. It establishes itself on the bark, stems, leaves, and fruit. Because of its protective waxy armor, it is well-defended against environmental stressors, making it a persistent agricultural challenge.

The life cycle begins with the egg stage, which develops under the protective cover of the adult female. Once hatched, the mobile 'crawlers' emerge and search for a suitable site on the host plant to settle. After inserting their stylets into the plant tissue, they begin to secrete their characteristic circular or oval scale covers and enter a sedentary life phase.

Damage is caused by the extraction of phloem sap from the host, which results in yellowing, chlorosis, and stunted development of leaves and shoots. Heavy infestations can lead to premature leaf drop, reduced vigor, and, in severe cases, the death of young shoots. On citrus, the presence of scale on the rind severely detracts from the marketability of the produce.

Effective management strategies incorporate a multi-faceted approach:

• Implementing integrated pest management (IPM) to maintain low population levels.
• Using horticultural mineral oils to suffocate active scale stages.
• Applying systemic insecticides during the peak crawler emergence period.
• Conserving and releasing natural enemies, such as Aphytis species of parasitoid wasps.
• Pruning and destroying heavily infested plant material to reduce local population density.