Turnip sawfly

Systematic position: The turnip sawfly (lat. Athalia rosae) belongs to the order Hymenoptera, family Tenthredinidae. It is a highly specialized and aggressive pest that can cause severe damage to commercial crops by defoliating them rapidly during the larval stage.

Host crops: The primary hosts include Brassicaceae species such as winter oilseed rape and garden cabbage. While it predominantly targets crucifers, in years of high population density, it may cause incidental damage to forage beet, peas, and various cereals like winter wheat or barley, though these are not its preferred breeding grounds.

Biology and life cycle: The pest typically completes two to three generations per year. It overwinters as a mature larva in a cocoon deep within the soil. During the spring, pupation occurs, followed by the emergence of adults. Females utilize their saw-like ovipositor to insert eggs into the leaf tissue of host plants.

Damage patterns and economic impact: The larvae, often called false caterpillars, are the destructive stage. Young larvae create small holes in leaves, while older larvae devour the entire leaf blade, leaving only the midribs intact. This heavy defoliation stunts plant growth, reduces photosynthetic efficiency, and often results in complete loss of yield if left untreated.

Protection measures:

• Deep autumn plowing to disturb and destroy overwintering cocoons in the soil.
• Control of cruciferous weeds that provide early-season feeding sites.
• Crop rotation to break the pest's life cycle and prevent population buildup.
• Timely application of chemical insecticides when economic injury levels are exceeded.