Control Methods for Dacne japonica Infestation on Lingzhi (Ganoderma lucidum)

Dacne japonica Crotch, also known as the small fungus beetle or red concave fungus beetle, belongs to the order Coleoptera, family Erotylidae.

1. Morphology and habits: The adult is 3-4.5 mm long, elongated oval, glossy. The head is yellowish-brown; the antennae have 11 segments and are brown. The compound eyes are large and spherical. The pronotum is wider than long, yellowish-brown, darker in the middle. Each elytron bears one square black spot on the inner basal margin; the basal half of the elytra is yellowish-brown and the apex is black. The legs are yellowish-brown and relatively slender. From the shoulder angle diagonally toward the median suture there are red-yellow markings that meet, and on the elytral dorsum these red-yellow markings almost form the shape of the Chinese character "concave", hence the name concave yellow fungus beetle. The newly hatched larva is 0.8 mm long, and the mature larva is 5-6 mm, yellowish-white, with a brown head and pale yellow legs.

Two generations occur per year, and 3-4 generations can occur indoors, overwintering as mature larvae and adults. Activity begins in early April, and eggs are laid from mid-April to late May. The adults exhibit death-feigning behavior and prefer to live in groups. From late May to June they hatch into larvae, pupate in late June, emerge as adults in late July, and mate and lay eggs in mid-August.

2. Damage: The adults mostly gnaw the mycelium at the edges of cracks or holes in the log, and after the fruiting body appears they move to feed on the stipe and cap. The larvae mostly bore from the surface into the wood, tunneling in crisscrossing galleries to feed on the mycelium. They also damage the fruiting body, forming winding tunnels, and therefore greatly affect the yield and quality grade of lingzhi.

3. Control methods

(1) Maintain good sanitation in the cultivation site and warehouse, and deal with pest infestations promptly when found.

(2) If Dacne japonica infestation is found in self-produced or purchased lingzhi fruiting bodies, spread them on concrete at above 45°C and sun them for 2 days, then seal and store them in the warehouse. If conditions permit, place them in a cold store below 0°C for 3-5 days, which can freeze the pests to death.

(3) Infested logs or fruiting bodies can be fumigated with aluminum phosphide in a sealed space to kill the insects.