Locusts descend on East Africa

East Africans are currently facing the worst swarms of locusts seen in decades

Writer: Harry Dodd
Editor: Altay Shaw
Artist: Victoria Kozlova


In the midst of the current SARS-CoV-2 Pandemic, fuelled by anxiety, some may cast their minds back to plagues previously endured by humanity. From the Black Death of the 14th century to the Spanish Flu of 1918, there are several pandemics to choose from. Those who are religious may be reminded of the 10 plagues the Egyptians were said to have endured in the 5th century BCE, with images of rivers turning to blood and perhaps even the odd plague of locusts. The latter is rapidly becoming  a frightening reality for East African farmers however, who are currently enduring the worst locust swarms in a generation.

For those without a background in entomology, a locust is not a specific species of insect but rather a moniker for the swarming phase of a variety of species of grasshopper’s life cycles. This transformation from innocuous insect to crop devourer only occurs under specific conditions, triggered by serotonin (the very same hormone that contributes to happiness in people). Certain species of grasshoppers release these hormones under conditions of overcrowding, when vegetable matter is plentiful and the population booms. 

Since 2018, the Arabian peninsula has received several extraordinarily strong storms, which have caused lakes to form in the usually arid region, allowing the area to flourish with vegetation. This provided an ideal breeding ground allowing the population of the desert locust, Schistocera gregaria, to grow exponentially. It soon reached a density that resulted in a mass transformation into the swarming phase of their lifecycle. Due to the repeated onset of these storms, the vegetation has persisted for far longer than would usually occur, allowing the size of the locust swarms to reach biblical proportions. Each generation of locusts can produce a subsequent generation with 20 times the individuals, producing swarms estimated to be in the hundreds of billions. The cyclones also have the added effect of dispersing the swarms over a greater area, allowing them to spread farther and faster.

What does this mean for farmers? 

An individual mature desert locust is capable of devouring its own body weight in food every day, which amounts to around 2.5 grams. Though this may seem insignificant on its own, keep in mind that swarms can reach densities of 1500 locusts per m3, covering areas of up to 1000km. The largest swarms have been known to eat nearly 200 million kg of crop per day. This means that a single swarm of locusts can be responsible for devouring the yearly maize output of 20 subsistence farming villages in a single day. As most of these villages rely on what they grow to feed themselves, the loss of this can be completely devastating, resulting in the collapse of entire communities. An average of 40% of East Africans survive via subsistence farming, so the potential devastating effects of large scale crop loss are clear.

The costs so far

The United Nations have estimated that 25 million people have currently been put into a situation of food insecurity. This comes at a time when many in affected countries are already struggling economically due to lockdown orders caused by the Coronavirus pandemic. Many East African countries are members of the Desert Locust Control Organisation –  an organisation responsible for finding solutions to locust plagues. However many countries are unable to afford membership, leading to limited capacity for action as poor funding leads to poor preparedness. Therefore, only countries with their own control programmes, such as Kenya, are capable of mounting any serious defence against the coming swarms through the use of pesticides. This is leading to many already disadvantaged countries falling further into debt, as their economies are heavily dependent on agriculture.

Tackling the problem

Despite the direness of the situation, there is hope. Every year new control methods are being developed to be more effective, affordable, and less damaging to the environment. The new trend is the use of biopesticides. These are based upon organisms that can control locust populations whilst minimising collateral environmental damage. As they can be grown, they are also relatively cheaper to produce than some industrial pesticides, though they are slower to act than conventional chemical methods. One example is Metarhizium anisopliae. M.anisopliae is a fungus that naturally occurs in soils over much of the world. It is also specialised to infect and kill insects, specifically in their juvenile stages. This means that mass application of the biopesticide over the locust’s breeding grounds will halt the formation of new swarms in its tracks.

While it may be too late to stop the swarms already plaguing East Africa using biopesticides, there is still time to prevent future losses. For the moment, countries have to focus on limiting the damage caused by the locusts, even if this requires use of chemicals that in the long term may cause even more damage to the ecosystem, and in turn farmer’s yields.

References 

Lambert, M., Traoré, P., Blaes, X., Baret, P. and Defourny, P., 2018. Estimating smallholder crops production at village level from Sentinel-2 time series in Mali’s cotton belt. Remote Sensing of Environment, 216, pp.647-657.

Goldsworthy, G. and Wheeler, C., 2018. Insect Flight. Boca Raton, FL: CRC Press.

National Geographic. 2020. Locusts. [online] Available here [Accessed 14 April 2020].

Peveling, R., Attignon, S., Langewald, J. & Ouambama, Z. Crop Prot. 18, 323–339 (1999).

Roussi, A., 2020. Why gigantic locust swarms are challenging governments and researchers. Nature, 579(7799), pp.330-330.

Bukhari, T., Takken, W. and Koenraadt, C., 2011. Development of Metarhizium anisopliae and Beauveria bassiana formulations for control of malaria mosquito larvae. Parasites & Vectors, 4(1).

World Bank. 2020. Agriculture In Africa: Telling Facts From Myths. [online] Available here [Accessed 22 April 2020].

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