froggy:How do/if they digest cellulose?
BSF larvae can't digest cellulose. Dr. Olivier is excited about combining BSF culturing with vermiculture because earthworms can digest what BSF can't and visa versa. He sighted some research that indicates a dramatic improvement in earthworm growth when they are raised in the compost from a BSF unit.
froggy: If the poop has a pathogen... does the pathogen remain viable in the fly?
There is evidence from various studies that BSF digestion destroys pathogens including ecoli and salmonella. Here's one example:
Bacteriological interactions associated with manure digestion by
maggots are favorable. Maggots are competitors with bacteria for
nutrients and often reduce bacterial numbers greatly, or eliminated
them altogether (Beard and Sands, 1973; Sherman, 2000). Maggots may
consume and digest microorganisms, and produce antibacterial and/or
fungicidal compounds (Landi, 1960; Hoffmann and Hetru, 1992; Levashina
et al., 1995 and Landon et al., 1997). As maggots reduce pathogens in
manure they may make it safer for organic vegetable production.
SOURCE
When the larvae transform into the prepupal stage they undergo changes that facilitate migration away from the food source and pupation. Their mouth is replaced with a hook-like appendage to aid crawling, they purge their gut, and they excrete an antibiotic as mentioned in the quote above. The consensus from my reading is that all flies emerge from their pupae sterile.
I have a post about pathogens relating to BSF culturing on my blog here.
froggy: Heavy metals? Im sure they bioaccumulate like everything else.
That's a good question and I assume the same thing you do. I'm interested if anyone finds information about this.
froggy: Is there a prefered foodtype? Protein? Lipid? Carbo? Is there first/second/third ranking of the 3?
From my experience I would say that the larvae gravitate towards whatever is easiest to consume, with a few exceptions. The most popular items I've fed my colony include fruit (the softer the better), whole fish, dog food, sour cream, moistened bread, and the exception; coffee grounds. I'm very curious about the coffee grounds. Meats, hard fruit and vegetables and dry grains need to soften before they can consume them quickly, but in the absence of other food they will work on these items. All of that considered, BSF larvae will consistently consume waste before bacteria can bloom, resulting in a process that is nearly odor free. Corresponding blog post here.
Thanks for the good questions froggy.
