Stem weevil

The stem weevil (Tyloderma morbillosus) belongs to the order Coleoptera and the family Curculionidae. This species is known as a specialized stem borer, with larvae completing their development deep within plant tissues, making detection challenging for agronomists and farmers until visible damage occurs.

This pest primarily infests plants within the Asteraceae family, with a particular affinity for members of the Silphium genus. By boring into the core of the stem, the larvae disrupt the vascular bundles, which impairs nutrient and water transport, leading to physiological stress within the infested plant host.

The life cycle involves a complete metamorphosis, consisting of the egg, larva, pupa, and adult stages. Females typically deposit eggs directly into the stem tissue. Larvae emerge and immediately begin tunneling. The insect generally overwinters as an adult, seeking shelter in plant debris or soil, and becomes active again as temperatures rise in the spring.

The damage caused by Tyloderma morbillosus is significant, characterized by the wilting of terminal shoots, stem deformation, and stunted growth. Infested plants often exhibit structural weakness, making them prone to lodging. In severe cases, the infestation can lead to total crop failure and a drastic reduction in seed yield and quality.

Integrated pest management strategies are essential for controlling this beetle. Cultural practices such as crop rotation, residue destruction after harvest, and the removal of alternative weed hosts are crucial. During the peak adult activity period, targeted applications of systemic insecticides may be necessary to minimize egg-laying and prevent widespread damage.