Turnip sawfly

Taxonomic classification. The turnip sawfly (Latin: Athalia lugens) is a member of the order Hymenoptera, family Tenthredinidae. It is a major agricultural pest known for targeting plants belonging to the Brassicaceae family. It is widely distributed across regions where rape and mustard are grown as primary commercial crops.

Host plants. The primary hosts include various cruciferous crops such as oilseed rape (canola), mustard, radish, cabbage, turnip, and kale. In addition to commercial fields, the pest thrives on wild Brassicaceae species, which often serve as primary breeding sites before the insects migrate to cultivated fields.

Biology and lifecycle. The adult is a small wasp-like insect with an orange body and a black head. The life cycle involves complete metamorphosis, including egg, larva (often called false caterpillar), pupa, and adult stages. Females lay eggs inside the leaf tissue using their serrated ovipositor. The larvae undergo several molts before pupating in the soil. Under favorable conditions, the species completes multiple generations per year.

Damage and economic impact. The larvae are responsible for the damage. Early-stage larvae skeletonize the leaves, while older larvae consume entire leaf blades, leaving only the primary veins. This heavy defoliation significantly impairs plant development, stunts growth, and can result in total crop failure, particularly when seedlings are attacked early in the growing season.

Control measures. Integrated pest management (IPM) is essential for controlling Athalia lugens. Cultural practices include deep plowing after harvest to destroy pupae residing in the soil and regular weed management to remove alternative food sources. Chemical control is required when the infestation exceeds the economic threshold, typically involving the application of registered insecticides to protect the foliage during peak larval activity.