Poplar shoot sawfly

Poplar shoot sawfly (Janus abbreviatus) is a hymenopteran insect belonging to the family Cephidae. This pest primarily targets trees within the Salicaceae family, specifically focusing on various species of poplar (Populus) and, to a lesser extent, willow species found in nursery plantations and managed forests.

The damage caused by this insect is concentrated on the current year's growth. By damaging the terminal shoots, the larvae significantly impact the tree's vertical development and structural integrity, which is particularly detrimental in younger trees that have not yet established a strong main stem.

The life cycle involves the adult female utilizing her ovipositor to deposit eggs inside the soft tissue of developing shoots. After hatching, the larvae bore into the central pith of the shoot, creating a tunnel that disrupts the plant's ability to transport nutrients and water effectively through the stem.

Symptoms of infestation include the wilting and browning of shoot tips, often leading to the eventual breakage of the stem at the damaged point. Such destruction results in multiple side branches forming, which ruins the apical dominance and leads to a stunted or deformed appearance of the host plant.

Effective management strategies require a combination of cultural and chemical interventions to maintain plant health and suppress the population of the pest:

• Pruning and destroying infested shoots early in the season to remove larvae before they emerge.
• Applying systemic insecticides during the period when adult females are actively seeking sites for oviposition.
• Monitoring adult flight activity to time protective measures accurately.
• Encouraging the presence of natural predators and parasitoids in the nursery environment.