The Food and Agriculture Organization (FAO) has recently focused on insects as a source of proteins for the increasing population (1). However this makes me doubt, being insects on the second level of the trophic chain. As far as I know vegan diet is the most sustainable, and vegetable food has the higher protein conversion ratio; this means that vegetable diet is the most efficient to transfer protein to humans, while meat production requires loads of proteins to feed animals that will feed us. I wonder which is the protein conversion ratio for insects, and whether they need to be fed with grains when raised in large-scale plants. So in the end are insects the answer to world hunger? or is vegan diet? (or ban to the land-grabbing?)
According to the FAO report, crickets have a live weight feed conversion ratio of 1.7. This means 1kg of live cricket requires 1.7kg of feed. Crickets are approximately 80% edible, giving a feed-to-food ratio of about 2.1. According to the report, "this means that crickets are twice as efficient in converting feed to meat as chicken, at least four times more efficient than pigs, and 12 times more efficient than cattle."
This is of course, not as efficient as if we just ate the feed directly which would give a feed to food ratio of 1. Growing feed for insects is not more efficient than growing feed for ourselves. One way insects might improve sustainability over a purely vegan diet would be to farm insects which feed on biowaste as “practically every substance of organic origin, including cellulose, is fed upon by one or more species of insects".