Lesion

Definition

A localized area of damaged, altered, or non-functional tissue in an organism, resulting from injury, infection, parasitism, or disease. In arthropods, lesions may appear as necrotic spots, melanized patches, or structural deformities on the cuticle, gut epithelium, or other tissues, often serving as diagnostic signs of pathogen infection or parasitoid attack.

Etymology

Latin laesio, meaning 'injury' or 'wounding'

Example

A honey bee infected with Deformed wing virus may develop melanized lesions on the pupal cuticle, visible as dark, hardened spots where viral replication has destroyed underlying epidermal cells.

Related Terms

• Necrosis
• melanization
• Pathology
• Cuticle
• epithelium
• Parasitoid
• Vector
• host-pathogen interaction

Usage Notes

In entomology, 'lesion' typically describes macroscopic or microscopic tissue damage visible during dissection or histology, distinct from behavioral symptoms or systemic infection signs. Specialists may distinguish primary lesions (direct pathogen damage) from secondary lesions (host immune response, such as melanization encapsulating a parasitoid egg). The term is broadly applicable across plants, animals, and fungi, but precision requires specifying tissue type and causal agent.