Post-harvest insect pest directory
Four-spotted fungus beetle
Scientific name: Mycetophagus quadriguttatus (Müller)
- Order
- Coleoptera
- Classification
- Secondary
- Incubation at 20 C
- 7-12 days
- Incubation at 30 C
- 4-6 days
Description
Mycetophagus quadriguttatus (Müller), the Four-spotted Fungus Beetle, is small (3.3–4.0 mm). Adults are generally dark brown, with distinctly bicolored elytra ornamented by yellowish to reddish maculae. The pronotum bears two deep foveae near the basal margin, visible in dorsal view. The contrast between the dark ground color and the pale elytral markings gives a crisp, two-toned appearance.
Detection
Key signs of infestation by the Four-spotted fungus beetle, Mycetophagus quadriguttatus (Müller), in stored grain are tied to moisture and mold. The primary indicator is damp, moldy grain: kernels or fines bearing visible fungal growth (hyphae/mycelium), localized wet patches, and surface mold that can create crusted zones. Such conditions often herald the presence of this mycetophagous beetle, which is attracted to moldy substrates. However, the converse is not always true: the insect may be present even when the bulk is not obviously damp or visibly moldy.
Damages
A secondary, mycophagous pest of stored grain. Adults and larvae feed on fungal spores and hyphae and do not cause direct feeding injury—no kernel perforation, hollowing, or abrasion. The principal harm is indirect: adults act as mechanical vectors, transferring fungal propagules (conidia and hyphal fragments) throughout the grain bulk, which accelerates mold colonization, especially in moist hotspots. Consequences include elevated mold burden, musty off-odors, visible mycelial growth and caking, discoloration, downgraded grain quality, and increased risk of mycotoxin contamination when toxigenic molds are present. Economic losses arise from contamination and quality deterioration rather than physical damage to kernels.
Environment
Mycetophagus quadriguttatus favors stored‑product environments—grain silos, cereal granaries, flour mills, and warehouses—as well as residual feed and bagged grain.
Infested products
Feeds on molds and microscopic fungi. It is found in cereal grains, wheat, barley, oats, bran, rice, flour, bread, dried fruits, and moldy plant and animal materials.
Life cycle
The reproductive life cycle of Mycetophagus quadriguttatus, an insect pest that infests stored grain, generally follows these entomological stages:
- Egg: The female lays eggs in environments rich in decomposing organic matter, often near stored grain. Eggs are usually laid individually or in small groups.
- Larva: After hatching, the larvae emerge and begin feeding on organic matter, including mold present on the grain. This larval stage is crucial for the accumulation of nutrients necessary for growth.
- Pupa: Once the larval stage is complete, the larvae transform into pupae. During this stage, they undergo metamorphosis inside a cocoon, where they develop into adults.
- Adult: Adults emerge from the cocoons and are ready to reproduce. They continue to feed on organic matter and seek mates to reproduce, thus initiating a new reproductive cycle.
Each stage of the life cycle is influenced by environmental factors such as temperature, humidity, and food availability, which can affect the duration of each phase.
Geographical distribution
World.
Similar species
Species of the genus Cryptophagus
Species of the genus Atomaria
Hairy fungus beetle (Typhaea stercorea)