Mycodiplosis

Adults are small, delicate flies typical of gall midges (Cecidomyiidae), with reduced wing venation and long, slender legs. Species identification relies primarily on adult male morphology; larvae are found within spore-producing structures (uredinia, aecia) of rust fungi. The genus can be distinguished from other Cecidomyiidae by association with fungal hosts and larval feeding on spores rather than plant tissue.

Associated with rust-infected plants, specifically the spore-producing structures of Pucciniales (rust fungi). Larvae occur on uredinia and aecia of rust fungi infecting diverse plant hosts. Habitat availability depends on presence of active rust infections with accessible spore masses.

Recorded from 25 of 44 surveyed countries across multiple continents. One clade has global distribution; 12 clades occur in the United States. GBIF records document presence in Denmark, Norway, and Sweden. Distribution within clades is partially explained by geographic origin.

Larval activity observed from March through June on some rust species (e.g., Phragmidium violaceum on Rubus sanguineus, Puccinia menthae on Mentha spicata). On late-season rusts such as Cerotelium fici on Ficus carica, larvae appear at infection onset and continue until November. Seasonality tracks rust fungal phenology rather than fixed calendar periods.

Larvae feed on aeciospores and urediniospores of rust fungi (Pucciniales). Second-stage larvae have been observed consuming 82.37% of uredio-pustules in some infections. Larvae also feed on spores of powdery mildews, downy mildews, Polythrincium trifolii, and Rhytisma acerinum. Adults: feeding habits unknown.

• Rust fungi (Pucciniales) - larval food sourcePrimary hosts; larvae detected on 261 of 1,350 rust-infected plant collections across 127 rust species. Five rust species infested at greater frequency than expected.
• Powdery mildews (Erysiphales) - larval food sourceSecondary host group; spores consumed by larvae.
• Downy mildews - larval food sourceSecondary host group; spores consumed by larvae.
• Polythrincium trifolii - larval food sourceSpecific fungal species documented as larval food.
• Rhytisma acerinum - larval food sourceSpecific fungal species documented as larval food.

Larval stage is the only confirmed feeding stage, consuming fungal spores. Second-stage larvae are particularly voracious. Complete life cycle details including egg placement, pupation sites, and adult longevity are not documented in available sources.

Larvae exhibit preferential feeding on certain rust species, though no strict host-specificity exists between larval clades and rust hosts at any taxonomic level. Infestation frequency varies by plant family: 100% occurrence on some families, 92.31% on Fabaceae, absence on Plumbaginaceae. Larval distribution within clades correlates partially with geographic origin.

Potential biological control agents for rust fungi. By consuming rust spores, larvae may reduce fungal reproductive output and disease severity. The ecological impact of this predation on rust population dynamics has not been quantified.

Interest as potential biological control agents for agricultural and forest rust diseases. No documented negative impacts on human activities.

• Other Cecidomyiidae gall midgesMany gall midge larvae feed on plant tissue or form galls; Mycodiplosis is distinguished by exclusive or primary feeding on fungal spores rather than plant material.

• fungivory
• rust fungi
• biological control
• Cecidomyiidae
• Pucciniales

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Survey of Mycodiplosis rübsaamen Larvae Feeding on the Rust Fungi and Their Plant Hosts
• Mycodiplosis (Diptera) infestation of rust fungi is frequent, wide spread and possibly host specific
• A Phylogenetic Analysis of Species Diversity, Specificity, and Distribution of Mycodiplosis on Rust Fungi