Plum curculio

Systematic position. The plum curculio, Coccotorus scutellaris, belongs to the order Coleoptera and the family Curculionidae. It is recognized as a significant agricultural pest that targets stone fruit trees. While primarily a concern in North American horticulture, its impact is studied globally due to the severe economic damage it inflicts on commercial fruit production.

Host plants and damage. The species is highly specialized, primarily infesting plums and other stone fruits. Adult beetles cause damage by feeding on buds and blossoms during the early spring. However, the most destructive stage is the larval phase. The larvae bore into the developing fruit, feeding on the pulp and the pit, which typically leads to premature fruit drop and rot.

Biology and life cycle. The life cycle consists of four distinct stages: egg, larva, pupa, and adult. Females create crescent-shaped incisions in the fruit to deposit their eggs. Once the larvae hatch, they burrow deeper into the fruit to feed. After completing their development, they exit the fruit to pupate in the soil, emerging later as adults to overwinter in leaf litter or soil crevices.

Economic impact. The plum curculio is considered one of the most critical pests in stone fruit orchards. An uncontrolled infestation can result in total loss of marketable fruit. Beyond physical consumption, the larvae create entry points for pathogens such as Monilinia species, causing brown rot, which rapidly spreads through the orchard and compromises overall tree health.

Control measures. Effective management requires an integrated pest management (IPM) approach to keep populations below economic injury levels:

• Sanitation: Regularly collect and destroy all fallen fruit to remove developing larvae.
• Soil cultivation: Tilling the soil under the canopy in late summer or autumn to disturb pupation sites.
• Chemical control: Applying targeted insecticides during the beetle's active emergence period, following economic threshold monitoring.
• Physical barriers: Utilizing sticky traps or trunk barriers to limit adult migration into the canopy.