serious environmental problems, at every scale from local to global." Some researchers argue that establishing sustainable production systems will depend upon a large-scale replacement of traditional livestock with edible insects; such a shift would require a major change in Western perceptions of edible insects, pressure to conserve remaining habitats, and an economic push for food systems that incorporate insects into the supply chain. In total, the emissions of the livestock sector account for 18 percent of total anthropogenic greenhouse gas emissions, a greater share than the transportation sector. Using the ratio between body growth realized and carbon production as an indicator of environmental impact, conventional agriculture practices entail substantial negative impacts as compared to entomophagy. The University of Wageningen analysis found that the production per kilogram of mass gain for the five insect species studied was 39-129% that of pigs and 12-54% that of cattle. This finding corroborates existing literature on the higher feed conversion efficiency of insects as compared to mammalian livestock. For four of the five species studied, GHG emission was "much lower than documented for pigs when expressed per kg of mass gain and only around 1% of the GHG emission for ruminants." Economic benefits Insects generally have a higher food conversion efficiency than more traditional meats, measured as efficiency of conversion of ingested food, or ECI. While many insects can have an energy input to protein output ratio of around 4:1, raised livestock has a ratio closer to 54:1. This is partially due to the fact that feed first needs to be grown for most traditional livestock. Additionally, endothermic (warm-blooded) vertebrates need to use a significantly greater amount of energy just to stay warm, whereas ectothermic (cold-blooded) plants or insects do not. An index that can be used as a measure is the Efficiency of conversion of ingested food to body substance: for example, only 10% of ingested food is converted to body substance by beef cattle, versus 19–31% by silkworms and 44% by German cockroaches. Studies concerning the house cricket (Acheta domesticus) provide further evidence for the efficiency of insects as a food source. When reared at 30 °C or more and fed a diet of equal quality to the diet used to rear conventional livestock, crickets showed a food conversion twice as efficient as pigs and broiler chicks, four times that of sheep, and six times higher than steers when losses in carcass trim