Conifer sawflies

Affected crops: They primarily infest various species of pine (Pinus), as well as spruce (Picea) and fir (Abies). While mature trees may survive defoliation, young plantations and nursery stocks are extremely susceptible to severe growth reduction and mortality following heavy sawfly outbreaks.

Biology and lifecycle: Conifer sawflies typically undergo one or more generations per year depending on the climate. Adults emerge in spring or autumn, and females deposit eggs into needles. The larvae, often gregarious, feed on the foliage and eventually drop to the ground to pupate in protective cocoons, often buried within the soil litter layer.

Damage and economic impact: Larvae feed on both current-year and older needles, depending on the species of sawfly. Early-stage damage appears as notched needle edges, while later stages consume the entire needle down to the sheath. Severe defoliation weakens the tree's defense mechanisms, making them susceptible to secondary infestations by bark beetles.

Protection measures: Management requires a multi-faceted approach. Monitoring for early signs of defoliation is crucial for timely intervention. Integrated pest management (IPM) strategies include:

• Conservation and augmentation of natural parasitoids and predators.
• Application of selective biological insecticides such as nucleopolyhedroviruses.
• Chemical control during the early larval stages when the insects are most vulnerable.
• Silvicultural practices to promote tree health and stand resistance.