Biodegradation of Pig Manure by the Housefly, Musca domestica: A Viable Ecological Strategy for Pig Manure Management

The technology for biodegradation of pig manure by using houseflies in a pilot plant capable of processing 500-700 kg of pig manure per week is described. A single adult cage loaded with 25,000 pupae produced 177.7 +/- 32.0 ml of eggs in a 15-day egg-collection period. With an inoculation ratio of 0.4-1.0 ml eggs/kg of manure, the amount of eggs produced by a single cage can suffice for the biodegradation of 178-444 kg of manure. Larval development varied among four different types of pig manure (centrifuged slurry, fresh manure, manure with sawdust, manure without sawdust). Larval survival ranged from 46.9 +/- 2.1%, in manure without sawdust, to 76.8 +/- 11.9% in centrifuged slurry. Larval development took 6-11 days, depending on the manure type. Processing of 1 kg of wet manure produced 43.9-74.3 g of housefly pupae and the weight of the residue after biodegradation decreased to 0.18-0.65 kg, with marked differences among manure types. Recommendations for the operation of industrial-scale biodegradation facilities are presented and discussed.