Western raspberry fruitworm

The Western raspberry fruitworm (Byturus bakeri) is a destructive insect pest belonging to the order Coleoptera and the family Byturidae. This beetle is a primary concern for commercial berry growers, as it specializes in feeding on the tissues of plants within the Rosaceae family, primarily focusing on Rubus species.

The host range is largely confined to raspberries and blackberries. Adult beetles emerge in early spring to feed on foliage and developing flower buds, which causes scarring and stunted growth. The larvae, however, cause the most significant economic damage by burrowing into the developing fruits, rendering them unmarketable.

The lifecycle of Byturus bakeri consists of a single annual generation. Overwintering occurs in the soil as pupae or adults. With the onset of warmer temperatures, they emerge and migrate to host plants to feed and mate. Eggs are laid directly onto the blossoms, and newly hatched larvae immediately penetrate the fruit receptacle to feed internally.

Damage is characterized by the presence of small, misshapen, or prematurely ripened fruits that often rot on the cane. The internal feeding of the larvae disrupts the development of the fruit, leading to significant yield reduction. Infested berries are often unfit for fresh market consumption due to the presence of larvae and frass inside the drupelets.

Integrated pest management (IPM) strategies are essential for controlling this beetle. Cultural practices, such as soil cultivation in the spring to disrupt pupation sites, are highly effective. Additionally, chemical control should be targeted during the pre-bloom stage to manage adult populations before they lay eggs on the blossoms.

• Cultivating soil around the base of the bushes.
• Monitoring adult activity with white sticky traps.
• Timed insecticide applications before full bloom.
• Sanitation by removing damaged or dropped fruit from the field.