Mushroom Culture

Familiarization with the Insect-Pests, Nematodes and Animal Pests of Mushrooms

1) MUSHROOM FLIES: Mushroom flies and midges are present in nature wherever fungi are found. Attracted by the odour of the decomposing manure and vegetable matter as well as smell of the growing mycelium, the adult female enters the composting yard or the mushroom farm and lay eggs on the compost, near the mycelium or fruiting bodies. Mainly three types of flies are known to infest mushroom beds:

1. Phorid fly or dung fly ( Megaselia nigra , M. halterata )
2. Sciarid fly or big fly ( Lycoriella solani , L. mali , L. auripila )
3. Cecids or gall midges ( Heteropeza pygmiae , Mycophila speyeri )

Fig. The adult, larva and wing venation of a phorid fly ( Top row ), Sciarid fly ( Middle row ) and a cecid fly ( Lower row ). The structure of a mother larva is also shown in case of cecid fly.

Nature of damage: The larvae of flies that emerge from the eggs laid in the mushroom beds, mainly cause the damage as they directly feed on the white mycelium spread in the compost and casing layer and also feed on the mushroom fruit bodies making tunnels through the stems. Mushrooms from the infested mushroom beds are found blackened from inside and infested with white larvae. Mushrooms infested at the pinhead stage become brown and remain stunted. Infested oyster mushrooms remain stunted, wrinkled and bent downwards with a large number of larvae and pupae lying embedded inside the tissues. Adult flies are the carriers of mites and mushroom pathogens such as spores of Verticillium, Trichoderma, Mycogone etc. attached to their hairy body parts.

Lifecycle: The adult female fly lays about 150-170 eggs in the compost or mushroom beds which hatch into larvae. After feeding for some time, each larva secretes from the mouth and forms a pupa. As a result of the metamorphological changes inside, larva turns into an adult fly and comes out of the pupal cell for causing further damage and breeding. In case of cecid flies, the reproduction takes place paedogenetically. Here a larva becomes mother larva and instead of forming a pupa, a mother larva carries about 14 – 16 larvae in its body which hatch out after few days. Thus they multiply in a very rapid manner and so the damage also increases.

Life cycle of a Phorid fly

Control measures:

• Strict hygiene in the mushroom house .
• Proper turnings during composting process.
• All the doors, windows, exhaust vents and fresh air intake openings should be fitted with fine wire mesh / mosquito netting.
• All the implements and tools should be cleaned and disinfected.
• Proper pasteurization of the compost at Phase –II with aerated steam at 58-59 ºC for 3-4 hours and the conditioning at 50-55º C till ammonia is eliminated.
• Drymixing of the casing materials, proper prewetting and its sterilization with steam at 65± 1ºC for 3-4 hours or with 5 % formalin solution .
• Use of light traps and sticking bands .
• Storage of raw materials in dry and ventilated rooms .
• The spent compost, after the end of the crop, should always be thrown away at a distant place.
• Growing rooms, all containers and equipments / implements should be cleaned with water and disinfected every time before and after the crop is over.
• Spraying beds with safe insecticides like malathion ( 0.05 % ) or DDVP ( 0.025 % ) one week before harvest .

2) MUSHROOM MITES: Mites are very small, spider like in appearance that live and breed in decomposing vegetable matter feeding on moulds present therein. They differ from the insects in that the mites have four pair of legs instead of three pairs. The environmental factors like moist and warm atmosphere ( 20 – 30 ºC ) and closed area support their exponential growth and a rapid succession of generation. Under adverse conditions, certain mites have the ability to change into an intermediate stage called a “ Hypopus ” which have flattened body, short stubby legs and a sucker plate with which they become attached to moving objects and thus are dispersed or carried away to distant places, mainly through the mushroom flies and human beings .

Fig. 12.3 Mushroom mites on the fruit bodies staying in groups
Fig. 12.4 An adult mushroom mite with four pair of legs

Nature of damage: Mites have the chewing type of mouth part with which they eat mycelia and the mushrooms. They devalue the crop causing certain spots on the surface and crawl into the pickers’ body causing discomfort.

LIFE CYCLE: The mites complete their life cycle within 13 days at 75 º F and 36 days at 60 º F as the high temperature facilitates rapid reproduction. They lay eggs which hatch into larva , protonymph and trironymph stages before reaching the adult reproductive stage .

Fig. 12.5 An adult mushroom mite

Control methods:

• Complete hygiene and sanitation
• Proper pasteurization of compost and casing materials
• Drenching mushroom houses and premises with endosulfan, diazinon or dicofol ( 0.1% ) .
• Use of fresh polythene bags and chemical sterilization of empty trays and trolleys.
• Burning sulphur in the empty rooms @ 2-3 lbs /1000 cu.ft.
• Cook out of the exhausted compost with live steam at 71ºC for 8–10 hours
• Disposal of spent compost at a distant place
• Spraying beds with safe insecticides like chlorfenvinphos, fenitrothion ( 1g a.i / m² bed area ) or malathion ( 0.05 % ) .