Stem sawfly

The stem sawfly (genus Trachelus) belongs to the order Hymenoptera and the family Cephidae. It is a significant pest of small grain cereals, known for its ability to cause severe lodging and yield loss in wheat and barley crops across various agricultural regions globally.

This pest primarily attacks wheat, barley, rye, and occasionally triticale. The larvae are stem-boring organisms that spend the majority of their developmental stage hidden inside the hollow or pithy stalks of the host plants, making them difficult to target with contact insecticides once inside.

The biological cycle is univoltine, meaning there is one generation per year. Adults emerge in the spring, coinciding with the heading stage of the crops. The female inserts eggs into the stem tissue. As the larva grows, it tunnels through the internodes toward the base of the plant, where it creates a chamber to overwinter as a mature larva.

The damage caused by Trachelus is characterized by the internal destruction of the stem's vascular system. This disruption prevents water and nutrient translocation to the head, resulting in premature ripening, stunted grain development (shriveling), and a weakened stem structure that leads to significant lodging before harvest.

Effective management strategies rely on a combination of cultural and chemical practices. Key methods include the use of resistant or solid-stemmed wheat varieties, deep tillage to bury stubble containing overwintering larvae, implementing crop rotation with non-host crops, and timely harvesting to minimize losses from stalk breakage.