4. Systems design
4.1. Systems exploiting natural fly populations
The simplest and least expensive manure management systems utilize natural fly populations for the management of organic waste. Simple modifications of manure basins and animal houses are typically employed to support natural populations of flies in the vicinity of the farm, allow oviposition of flies directly in manure pits or lagoons and to redirect larval search for suitable pupation sites. While these systems are relatively cheap and very easy to implement, they can usually be considered only in warm regions with mild winters and the fly species to be used should pose minimum environmental and health risks (i.e. it must not be a pest). Close monitoring is advised to assure the presence of desired fly species in abundant numbers.
A system utilizing naturally occurring black soldier fly population is described by Sheppard et al. (1994). An experimental 460 hen caged layer house was modified to support breeding and self-harvesting of black soldier fly larvae and prepupae. A 30 cm deep, 1.1 m wide slightly sloped concrete basin was created under the cage batteries. A wall against the central walkway was vertical, while the wall toward the outside of the house was sloped at 40 ° and formed a ramp for prepupae leaving the manure basins. A plastic pipe with a 1.5 cm gap at the top was placed at the top of the slope. Migrating soldier fly prepupae entered the pipe through this slot and were directed to the holding containers. A stable black soldier fly population was initially established by releasing several liters of black soldier fly prepupae near the facility; these created a robust natural population in the vicinity of the layer house. Females returning to oviposit near manure accumulating in basins under the hen battery cages soon created a large larval population. Up to 150,000 prepupae were collected weekly during the highest peeks in June of 1991. Monthly yields of prepupae reached 47–78 kg of prepupae/460 hens in June–August and 7–22 kg of prepupae/460 hens in September-December, following a cleanout of the manure basins. Ten percent (by weight) of weekly collected prepupae were released at the facility for regeneration of the natural colony.
Notable advantages of this system include low cost, no special equipment, potentially high yields of prepupae, less labor, no external energy input, and elimination of house fly breeding. On the other hand, even in a warm climate environment, there were notable seasonal shifts in fly and larval numbers resulting in variable yields of prepupae and a sharp decrease in production following basin cleanouts.
In Thailand, Nuov et al. (1995) devised a system for mass-rearing of blowflies (L. sericata) in raw pig manure. The manure was placed in shallow concrete tanks (1.5 × 2.5 × 0.25 m) in 100 kg batches in the farm yard and inoculation was carried out by the wild ovipositing blowflies (L. sericata). The larvae were allowed to develop for 5 days. After this period they were separated on a wire screen (6 mm mesh size). Several smaller ponds with manure were left unharvested to ensure adequate numbers of ovipositing females. While cheap and easy to implement, this system presents a great risk due to the large number of uncontained blowflies which can easily spread in the vicinity and become nuisance to local inhabitants as well as a potential vector of various diseases.
Although the more natural systems require less investment than mechanized, intensive systems, they failed to develop into viable businesses primarily because there were no established markets for the larvae or larvae products. It is interesting to speculate that if commodity markets for larvae develop in the future, that some lower cost, earlier demonstrated and proposed systems within animal housing may be revived.
4. Systems design4.1. Systems exploiting natural fly populationsThe simplest and least expensive manure management systems utilize natural fly populations for the management of organic waste. Simple modifications of manure basins and animal houses are typically employed to support natural populations of flies in the vicinity of the farm, allow oviposition of flies directly in manure pits or lagoons and to redirect larval search for suitable pupation sites. While these systems are relatively cheap and very easy to implement, they can usually be considered only in warm regions with mild winters and the fly species to be used should pose minimum environmental and health risks (i.e. it must not be a pest). Close monitoring is advised to assure the presence of desired fly species in abundant numbers.A system utilizing naturally occurring black soldier fly population is described by Sheppard et al. (1994). An experimental 460 hen caged layer house was modified to support breeding and self-harvesting of black soldier fly larvae and prepupae. A 30 cm deep, 1.1 m wide slightly sloped concrete basin was created under the cage batteries. A wall against the central walkway was vertical, while the wall toward the outside of the house was sloped at 40 ° and formed a ramp for prepupae leaving the manure basins. A plastic pipe with a 1.5 cm gap at the top was placed at the top of the slope. Migrating soldier fly prepupae entered the pipe through this slot and were directed to the holding containers. A stable black soldier fly population was initially established by releasing several liters of black soldier fly prepupae near the facility; these created a robust natural population in the vicinity of the layer house. Females returning to oviposit near manure accumulating in basins under the hen battery cages soon created a large larval population. Up to 150,000 prepupae were collected weekly during the highest peeks in June of 1991. Monthly yields of prepupae reached 47–78 kg of prepupae/460 hens in June–August and 7–22 kg of prepupae/460 hens in September-December, following a cleanout of the manure basins. Ten percent (by weight) of weekly collected prepupae were released at the facility for regeneration of the natural colony.Notable advantages of this system include low cost, no special equipment, potentially high yields of prepupae, less labor, no external energy input, and elimination of house fly breeding. On the other hand, even in a warm climate environment, there were notable seasonal shifts in fly and larval numbers resulting in variable yields of prepupae and a sharp decrease in production following basin cleanouts.In Thailand, Nuov et al. (1995) devised a system for mass-rearing of blowflies (L. sericata) in raw pig manure. The manure was placed in shallow concrete tanks (1.5 × 2.5 × 0.25 m) in 100 kg batches in the farm yard and inoculation was carried out by the wild ovipositing blowflies (L. sericata). The larvae were allowed to develop for 5 days. After this period they were separated on a wire screen (6 mm mesh size). Several smaller ponds with manure were left unharvested to ensure adequate numbers of ovipositing females. While cheap and easy to implement, this system presents a great risk due to the large number of uncontained blowflies which can easily spread in the vicinity and become nuisance to local inhabitants as well as a potential vector of various diseases.Although the more natural systems require less investment than mechanized, intensive systems, they failed to develop into viable businesses primarily because there were no established markets for the larvae or larvae products. It is interesting to speculate that if commodity markets for larvae develop in the future, that some lower cost, earlier demonstrated and proposed systems within animal housing may be revived.
การแปล กรุณารอสักครู่..
