Species of the genus Atomaria

Adults of Atomaria spp. are minute cryptophagid beetles, 2–3 mm long, oval and dorsoventrally flattened. The integument ranges from light to dark brown, with fine pubescence on the pronotum and elytra. Antennae are inserted on the frons very close together, a diagnostic trait distinguishing Atomaria from other Cryptophagidae. Larvae are active, slender and subcylindrical yet somewhat flattened, yellowish-brown; the head capsule, thoracic legs, and paired urogomphi are clearly visible.

Adults and larvae are fungivorous (mycophagous), grazing on fungal spores and hyphae, so they inflict no direct feeding injury to kernels. The primary impact is indirect: mobile adults act as vectors of fungal propagules (spores and hyphal fragments), disseminating them throughout the grain mass and storage surfaces. This promotes mold establishment and proliferation in stored grain, increasing fungal load and accelerating spoilage. Outcomes include musty odors, visible mold foci, quality downgrades, reduced marketability, and compromised storage hygiene.

Signs of Atomaria spp. (Cryptophagidae) in stored grain: - Damp, moldy patches, caking, and a musty odor driven by fungal growth. - Clusters of minute beetles (~1.5–3 mm), brown, oval, pubescent, with 11-segmented antennae ending in a club; adults run on the grain surface when disturbed and aggregate in moist zones, under crusts, and along bin seams. - Pale, slender larvae and cast skins (exuviae) within moldy fines and spout-line accumulations. - Increased fines, visible mycelium, grain clumping, and hot spots with condensation. - Positive captures in probe or pitfall traps set near moisture gradients. - Dead adults and fragments in screenings and around aeration plenums. Note: Moist, moldy grain often presages Cryptophagidae (including Atomaria), but the converse is not always true—finding Atomaria does not necessarily mean the bulk is wet or visibly moldy.

Atomaria spp. (Cryptophagidae) are mycetophagous beetles that exploit damp, moldy grain. Their reproduction is holometabolous. Oviposition: females deposit eggs singly on and among fungal hyphae. Larval development: mycetophagous larvae progress through successive instars within the grain mass, grazing hyphae and spores where moisture sustains mold. Pupation: occurs in situ in the commodity or fine detritus. Adults: long‑lived, volant (macropterous) beetles that disperse readily to new humid foci. Population dynamics: fecundity and development are strongly temperature‑ and humidity‑dependent; when fungal growth persists, generations overlap and numbers escalate. Prevention: keep grain dry and well‑aerated to interrupt fungal substrates and break the breeding cycle.

Atomaria spp. thrive in cool, humid, poorly ventilated stores where grain is damp and moldy. Hygrophilous, mycetophagous and saprophilous, they colonize granaries, warehouses, mills, and cellars - an indicator of poor storage hygiene and elevated moisture.

Four-spotted fungus beetle (Mycetophagus quadriguttatus) Hairy fungus beetle (Typhaea stercorea) Other Cryptophagidae species (species of the genus Cryptophagus)