Plane tree psyllid

Systematic position: The species Psyllopsis discrepans is a member of the Hemiptera order, within the Psyllidae family. Often referred to as a plane tree psyllid, this insect is a specialized pest that exclusively feeds on trees of the Platanus genus, maintaining a strict biological dependency on its host plant throughout its life cycle.

Affected crops and damage: The primary hosts are the Oriental plane (Platanus orientalis) and the London plane (Platanus × acerifolia). Both nymphs and adults feed by extracting phloem sap from the leaves. This feeding activity causes chlorotic spotting, leaf deformation, curling, and eventually premature leaf drop, which can significantly reduce the aesthetic value of ornamental street trees.

Biology and life cycle: The lifecycle is synchronized with the phenology of the plane tree. The species typically overwinters as fertilized females or eggs sheltered within the bark crevices. In early spring, following the bud burst, the nymphs emerge and migrate to the tender emerging foliage to initiate feeding, progressing through several instars before reaching the adult stage.

Pest impact: Beyond the direct physiological stress caused by sap removal, the psyllids excrete copious amounts of honeydew. This sticky substance serves as an ideal substrate for the development of sooty mold fungi. The thick layer of mold blocks sunlight and clogs stomata, severely impeding the photosynthetic capacity and overall vigor of the host tree.

Control measures: Management strategies focus on early detection before the population reaches damaging levels. Integrated pest management (IPM) practices include the application of contact or systemic insecticides during the critical nymph emergence phase. Cultural practices, such as removing loose bark during dormancy and ensuring proper tree nutrition, also play a vital role in increasing the tree's resilience to infestation.