Alfalfa seed chalcid

The alfalfa seed chalcid (lat. Bruchophagus roddi) is a member of the order Hymenoptera and the family Eurytomidae. It is a highly specialized pest that targets alfalfa seed crops, often causing severe economic losses in seed production areas by rendering the seeds hollow and non-viable.

The primary host plant is alfalfa (Medicago sativa). While the insect is host-specific, managing surrounding crops such as oilseed rape, cabbage, hemp, or various cereals is part of overall farm hygiene, as maintaining healthy crop rotation patterns helps reduce the localized population density of this pest.

The lifecycle of the alfalfa seed chalcid is synchronized with the flowering and seed development stages of the alfalfa plant. The female uses her ovipositor to deposit eggs inside the developing pods. The larvae then feed internally on the endosperm and embryo, completing their development within the seed coat.

The primary symptom of infestation is the presence of hollow, light-weight seeds that fail to germinate. Damage is often only visible once the adult wasps emerge, leaving distinct circular exit holes. High infestation rates can significantly reduce the marketability and germination quality of the seed harvest.

Management strategies focus on cultural practices, including the destruction of infested seeds after harvest, removing volunteer alfalfa plants, and using wide-area crop rotation. Chemical control involves the strategic application of insecticides during the adult flight period, specifically targeting the window before egg-laying occurs.