Green pine sawfly

The green pine sawfly (Gilpinia virens) is a species of hymenopteran insect belonging to the family Diprionidae. As a specialized defoliator, it specifically targets coniferous tree species, primarily focusing on pines, which can lead to significant economic losses in silviculture and nursery operations.

The primary host for this pest is the Scots pine (Pinus sylvestris). Larvae feed on the needles of the host plant, and while they initially focus on younger needles, their high population densities can cause complete defoliation of the tree canopy, leading to severe physiological stress and reduced growth rates.

Regarding their life cycle, the adult female uses her saw-like ovipositor to insert eggs into the pine needles. After hatching, the larvae go through several developmental instars. They typically feed in groups, which is a characteristic behavioral trait that makes them highly visible during the early stages of an infestation before they eventually pupate in protective cocoons.

The damage caused by Gilpinia virens is categorized by the degree of needle loss. Early instars typically eat the outer edges of the needles, while older larvae consume the entire needle down to the sheath. In cases of severe outbreaks, entire forest stands may appear scorched, which significantly impairs the tree's photosynthetic capacity and weakens its overall health.

Integrated Pest Management (IPM) is essential for controlling this sawfly:

• Monitoring population levels via pheromone traps to predict outbreaks.
• Encouraging natural predators such as parasitic wasps and predatory beetles.
• Application of biological control agents, including specific nucleopolyhedroviruses.
• Targeted insecticide applications during the early larval stages when the pest is most vulnerable to chemical control.