Eating Bugs to Save the World

The Food and Agriculture Organization of the United Nations (FAO) estimate around 70% of all agricultural land is dedicated to farming livestock, and with our ever-growing global population, our demand for beef and other livestock products is set to double by 2050. This is clearly unsustainable and will bring with it a vast increase in the rates of deforestation and water quality degradation through the leaching of manure run-off into our groundwater.

Agriculture as a whole is already thought to be the primary driving force behind anthropogenically-caused climate change, and livestock farming is responsible for 18% of all greenhouse gas emissions, a greater proportion than that of the automotive and aviation sectors combined. We are obviously in need of a drastic change in the way we produce our food, but are currently being let down, mainly by Western countries who are not yet ready to utilise the largely untapped entomological resource available to us. The idea of this post is to explain the ecological benefits of eating bugs and making entomophagy the change that the global food industry so crucially needs.

Energy Conversion Efficiency

Livestock require a lot of plant material in order to produce their own protein and the efficiency at which they do this varies with species. A number of researchers have compared this variation. Smil (2002) showed that beef cattle require around 10kg of feed to produce 1kg of their own weight in edible meat. This figure is 5kg for pigs and 2.5kg for poultry. Collavo and colleagues (2005) then found that it only takes 1.7kg of feed to produce 1kg of crickets.

Eating Bugs & Energy Conversion Efficiency
Edible weight produced from 100kg of feed - Data from Smil (2002) and Collavo et al. (2005)

This difference in energy conversion efficiency is further amplified when you consider that at least 80% of a cricket is edible, whereas only 55% of pig and chicken weight are eaten in the West, and this drops to around 40% for beef cattle. The outcome is that crickets are at least 12 times more efficient energy converters than cattle when you consider the amount of edible weight produced. Using these numbers, you can calculate the edible weight of each animal produced from 100kg of feed, as shown in the (not to scale) diagram above. It turns out that only 4kg of beef is produced, and this rises to 11kg for pork, 22kg for chicken, and finally 47kg for crickets. One of the reasons that crickets are so much more efficient than the rest is because they are cold-blooded and so don’t require energy from food to heat their bodies.

Another study by the FAO (2012) estimated that by 2025, around two-thirds of the world’s population will be under water stress and 1.8 billion people of these will experience complete water scarcity. Since current agricultural methods consume 70% of all global fresh water, there is surely room for improvement. Once again, the amount of water needed to produce 1kg of protein scales with the size of the animal. Chickens need 2,300 litres, pigs need 3,500 litres, and beef cattle need 22,000 litres (Pimentel et al., 2004). We do not yet have a figure for crickets as a comparison, but mealworms, for example, are much more drought-resistant than cattle so you can assume that they require a lot less water to produce the same amount of edible protein. In fact, other than the water required to produce their feed in the first place (of which we have already seen they require much less of than do cattle), mealworms get all of their water from their food, be that their feed/bedding or the additional moisture sources given (e.g. apple slices).

Land Use Efficiency

Not only do the more conventional food animals use more water in their rearing, they require much more land area than do our edible bugs. Using mealworms as an example again, they will happily live in a much more crowded environment than cattle will (though they do need a substrate to crawl through to make the crowding appear less extreme). Oonincx and de Boer (2012) calculated that for every hectare of land used to farm mealworms, 2-3.5 ha would be needed to produce the same amount of protein from pigs or chicken, and 10 ha would be needed for beef cattle. The graph to the right shows the amount of land required to produce 1kg of protein for each of these food animals. By my count so far, that’s bugs: three, beef: nil.

Eating Bugs & Land Use Efficiency
Area of land required to produce 1kg of animal protein - Data from Oonincx and de Boer (2012)

Greenhouse Gas Emissions

Eating Bugs & Greenhouse Gas Emissions
Top: greenhouse gas emissions per kg of animal mass; Bottom: ammonia release per kg - Data from Oonincx et al. (2010)

We have already touched on the fact that livestock farming is the largest contributor to global greenhouse gas emissions at 18% of the total, but let’s get into a bit more detail. Livestock farming is actually only responsible for 9% of global carbon dioxide emissions, and while this by itself not a huge proportion, it is also behind 35-40% of methane emissions and 65% of nitrous oxide emissions. The kicker is that the latter two are known to have a much higher global warming potential than CO2 , in fact 23 and 289 times as much, respectively. So this 18% contribution to total emissions now begins to look a lot more serious than at first glance. On the flip-side, very few edible insects produce methane at all since most lack the necessary gut bacteria that actually produce the gas.

However, gases are not the only issue here. Waste and urine from livestock releases ammonia into the groundwater and this leaching effect means it becomes a considerable environmental hazard on its own. Oonincx and colleagues (2010) again show how both greenhouse gas emissions and ammonia release compares between species, as shown in the set of graphs above. You’ll notice that the three insects represented here barely register on the graph of greenhouse gas emissions when compared to beef cattle and the maximum emission for pigs. The bottom graph doesn’t include cattle, but you can see that pigs are bad enough for ammonia release when compared to our six-legged friends.

Eating Bugs & Risks of Zoonotic Infections

Zoonotic infections are diseases transmitted between animals and humans. Many diseases carry a risk of being transmitted this way, but perhaps the most well-known example is the HIV-1 virus, which is believed to have been first transmitted via chimpanzees in the early twentieth century.

Livestock rearing involves many animals being kept together in a relatively small area and the periodic transport of some of these is essential for maintaining stocks on any farm. It is therefore quite easy to see how some of these diseases, once acquired, are spread through the population. Anyone around in the UK during the 2001 and 2007 foot-and-mouth epidemics will be familiar with the effects that such a spread of disease can have on everyday life. I was working for a countryside veterinary practice during the 2001 outbreak and impact on local farmers was severe. Whole farm populations of cattle had to be burnt on pyres if even one animal was found to be infected, in order to prevent the spread to neighbouring farms.

So where do our bugs come into this? Although a lot more research needs to be done in order to accurately assess the risk that insects might have in spreading diseases like this and transmitting them to humans, the ability of a particular pathogen adapting to a new human host is largely dependent on how genetically different the original host is from us. In other words, it is theoretically a lot more likely for a disease to jump from cattle to humans than from insects.

Like I said, more research is needed, but the future for bugs looks bright indeed. I could go on with the benefits of eating bugs, including how they can be farmed for feed using the run-off waste from livestock farming, or how they can be ethically euthanised through freezing, but you have plenty of evidence here already.

Collavo, A., Glew, R.H., Huang, Y.S., Chuang, L.T., Bosse, R. & Paoletti, M.G. (2005), House cricket small-scale farming. In M.G. Paoletti, ed., Ecological implications of minilivestock: potential of insects, rodents, frogs and snails. pp. 519–544. New Hampshire, Science Publishers.

FAO (2012), Water & poverty, an issue of life & livelihoods.

Oonincx, D.G.A.B., van Itterbeeck, J., Heetkamp, M. J. W., van den Brand, H., van Loon, J. & van Huis, A. (2010), An exploration on greenhouse gas and ammonia production by insect species suitable for animal or human consumption. PloS One, 5(12): e14445.

Oonincx, D.G.A.B. & de Boer, I.J.M. (2012), Environmental impact of the production of mealworms as a protein source for humans: a life cycle assessment. PLoS One, 7(12): e51145.

Pimentel, D., Berger, B., Filiberto, D., Newton, M., Wolfe, B., Karabinakis, E., Clark, S., Poon, E., Abbett, E. & Nandagopal, S. (2004), Water resources: agricultural and environmental issues.BioScience, 54: 909–918.

Smil, V. (2002), Worldwide transformation of diets, burdens of meat production and opportunities for novel food proteins. Enzyme and Microbial Technology, 30: 305–311.

Van Huis, A., Van Itterbeeck, J., Klunder, H., Mertens, E., Halloran, A., Muir, G., & Vantomme, P. (2013), Edible insects: future prospects for food and feed security (No. 171, p. 187). Food and agriculture organization of the United nations (FAO).