Recent reports of immense locust swarms in East Africa (and to a lesser extent in Pakistan), have led to comparisons with Biblical plagues. The numbers are extraordinary. Swarms can cover several square kilometres, with up to 80 million adult locusts per km2. With a following wind they can travel up to 130 km per day (FAO 2020). Kenya has it’s worst infestation for 25 years, Ethiopia it’s worst for 70.
Simply being in a swarm is dangerous, not from the insects themselves, but the asthma sensitisation they cause (Soparkar et al 1993).
But of course there is a much worse problem than that.
Even a very small, one-square-kilometre locust swarm can eat the same amount of food in one day as about 35,000 people (FAO, 2020). Farms can be wiped out in hours. And the locusts are not just eating and flying - with enough food each female locust can lay approximately 200 eggs, which emerge to augment the swarms.
The immediate loss of such vast quantities of food has obvious implications for health, and over 13 million people in Djibouti, Eritrea, Ethiopia, Kenya, and Somalia will experience “severe acute food insecurity,” according to the FAO, whilst another 20 million are at risk.
But the implications, economic and medical, go beyond that. Farmers in East Africa would normally plant most crops to coincide with the first rainy season, in March or April. Exactly the right conditions to boost new generations of locusts, not just from the fresh new crops, but the new growth across the countryside. And even once the swarms have passed, new crops need seeds. Many farmers use this year’s harvest for seeds for the next, except that there is no harvest.
A recent paper by Conte, Piemontese and Tapsoba (2020) focussed on the effect on child health of locust swarms in Mali, West Africa. This starts even before the locusts arrive, as food prices invariably rise due to speculative hoarding by suppliers. Then there is the, potentially devastating arrival of the locusts themselves, leading to acute food shortages. Both these effects have significant effects on child growth, especially if the child is in utero at the time, but perhaps surprisingly, there is little difference between those children exposed to the “speculative” phase and those exposed to the actual invasion. A factor that maybe should be borne in mind during disaster planning.
Whilst there are definite economic consequences for farmers post invasion, ranging from loss of seed stock to starvation of livestock, which are often also economic assets, there seems to be no strong effect on children born in the years afterwards, perhaps because the harvests were good.
The locust swarms this year are going to get worse before they get better. The rebuilding of agriculture will be a huge task in many countries, and a temporary one, the locusts will return.
Further reading
Conte, Bruno, Piemontese, Lavinia and Tapsoba, Augustin (2020). Ancient Plagues in Modern Times: The Impact of Desert Locust Invasions on Child Health. TSE Working Paper, n. 20-1069, Toulouse
Food and Agricultural Organisation of the United Nations (2020). http://www.fao.org/ag/locusts/en/info/info/faq/index.html
Soparkar GR, Patel PC, Cockcroft DW. (1993). Inhalant atopic sensitivity to grasshoppers in research laboratories. J Allergy Clin Immunol., 92(1 Pt 1), 61-5.