Tetrastichus evonymellae

Tetrastichus evonymellae is a species of hymenopteran insect belonging to the family Eulophidae. This parasitoid wasp is known for its complex interaction within the food chain, often functioning as a hyperparasite, which means it parasitizes other parasitoids that would otherwise control primary pest populations.

The host range of this insect mainly includes various species of ermine moths (Yponomeuta spp.). These moths are notorious pests on woody plants, such as cherry, euonymus, and apple trees, causing severe defoliation through their gregarious larval feeding behavior.

The life cycle of Tetrastichus evonymellae is closely synchronized with its hosts. The female deposits eggs into the larvae or pupae of the ermine moth. The developing larvae feed internally on the host tissues, eventually pupating inside or near the remains of the host. The species is capable of completing multiple generations within a single season.

The economic damage associated with this insect is indirect. While it is a natural enemy of the ermine moth, by attacking primary parasitoids, it interferes with biological control programs. This hyperparasitism can lead to lower suppression of pest populations, allowing ermine moths to cause more significant damage to ornamental and fruit-bearing trees.

Management practices should focus on an integrated pest management (IPM) approach.

• Avoid broad-spectrum insecticide applications during peak activity periods of beneficial insects.
• Promote biodiversity within the orchard to support stable populations of primary parasitoids.
• Monitor moth web presence to identify the need for targeted, low-impact control measures.