Predictability, toxicity, and trophic niche breadth in fungus‐feeding Drosophilidae (Diptera)

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Abstract
1. The mycophagous Drosophilidae flies in eastern North America display a range of ecological responses to their fungal trophic resources. Some (Drosophilu duncani Sturtevant, and two species labelled as Mycodrosophila cluytonae Wheeler and Takada) specialize on the bracket fungi of the family Polyporaceae. Other species (Drosophila falleni Wheeler, D.recens Wheeler, D.putridu Sturtevant and D.tripunctuta Loew) are broad generalists, non‐selectively consuming a diverse array of Basidioniycete mushrooms. D.restaceu von Roser and D.ordinuria Coquillett utilize a broad subset of the Basidio‐mycetes, while M.dimidiata hew feeds on some Basidioniycetes, including a variety of Clavariaceae (coral fungi) and Heterobasidiomycetes (jelly fungi) not commonly used by other flies, and Ascomycetes (cup fungi).2. Unlike some phytophagous insects, host chemistry seems to have little effect on host preferences. The mycophagous drosophilids do not avoid fungi thought to be toxic or undigestible to other Diptera.3. Resource predictability appears to delimit trophic niches in the mycophagous guild. The average duration of individual host mushroom caps is negatively correlated with three measures of trophic niche breadth. Specialist fly species utilize long‐lasting resources, while more generalized mycophagous species include progressively ephemeral fungi in their diets.