Turnip sawfly

The turnip sawfly (lat. Athalia rosae) is a destructive pest belonging to the order Hymenoptera and the family Tenthredinidae. It is a significant threat to various agricultural and horticultural crops, capable of causing widespread defoliation in fields and home gardens throughout its geographic range.

This pest specifically targets plants within the Brassicaceae family. Common host crops include turnips, rapeseed (canola), mustard, cabbage, broccoli, cauliflower, and radish. The larvae are notorious for their voracious feeding habits, which can lead to rapid crop depletion if left unmonitored during peak infestation periods.

The life cycle undergoes complete metamorphosis: egg, larva, pupa, and adult. Females use their saw-like ovipositors to insert eggs into the leaf margins. The larvae, often called false caterpillars, feed aggressively for several weeks. Once mature, they descend into the soil to pupate within a silken cocoon, which often serves as the overwintering stage.

The damage is characterized by skeletonization of the foliage. Young larvae chew small holes in the leaves, while later instars consume entire leaf blades, leaving only the primary veins intact. This severe damage significantly reduces the plant's photosynthetic capacity, often leading to stunted growth or total crop loss.

Effective management strategies require an integrated approach. Cultural controls include deep plowing after harvest to expose pupae to predators and environmental extremes, as well as strict weed control to eliminate alternative hosts. In commercial settings, chemical control using targeted insecticides is recommended when larval population densities exceed established economic thresholds.

• Deep tillage of soil to disrupt the pupation process.
• Regular inspection of fields for signs of larval feeding.
• Weed management to remove host plants.
• Use of selective insecticides to protect beneficial insects.