granuloviruses

Granuloviruses are baculoviruses of the genus Betabaculovirus. They infect insects, especially moths and other Lepidoptera, and are characterized by granular occlusion bodies that contain a single virion, a feature that distinguishes them from nucleopolyhedroviruses, which package multiple virions per occlusion body.

Granuloviruses have circular double-stranded DNA genomes, generally in the range of about 80 to 160 kilobases, encoding tens to around a hundred genes. Like other baculoviruses, they produce two virion forms during infection: occlusion-derived virus particles released from occlusion bodies and budded virus particles that spread within the host. In the life cycle, ingestion of occlusion bodies by a larva releases ODVs in the gut, initiating infection of midgut cells, followed by systemic spread to other tissues and eventual host death, after which new occlusion bodies are formed in the cuticle.

Granuloviruses generally exhibit narrow host ranges, enabling targeted biological control of pest populations. The best known example is Cydia pomonella granulovirus (CpGV), used commercially to manage codling moth in fruit orchards. Other granuloviruses are developed for pests such as tortricids and noctuids, and they are commonly formulated as sprayable products or baits for agricultural use.

Risks and production: Granuloviruses are considered environmentally safe with limited non-target effects and are compatible with integrated pest management. They are usually host-specific and can degrade under harsh environmental conditions; resistance can emerge with intensive use, prompting management strategies. Commercial granulovirus products are produced using infected insect larvae or insect cell culture and formulated to protect occlusion bodies until they are applied in the field.