Climate change and locust swarms in Africa: Unravelling the science

locust swarms in Africa

Climate change and locust swarms in Africa: Unravelling the science

The issue of locust swarms in Africa re-emerged as a destructive natural force, casting foreboding shadows over agricultural landscapes and food security. The complicated relationship between these ferocious insect armies and the unrelenting advancement of climate change, though, makes this rebirth more concerning.


This ecological issue is developing quickly and is grabbing the interest of communities, governments, and scientists alike. The biblical plague-like locust swarms that have recently returned to the forefront have left a path of destruction in their wake. However, this revival is closely related to the intricate and developing science of climate change and is not just a story of insect behavior. 


Grasshoppers known as locusts can swarm in groups of tens of thousands to millions. They can change from solitary to gregarious form, which implies they congregate in vast numbers, due to phase polymorphism. These are distinct colors and behave differently. 


The lone figure is dispersed and merges in with the surroundings. The gregarious form of the locusts develops as population density rises and the insects congregate. For swarms to develop, locusts must grow, concentrate, and assemble. 


The color and behavior of the gregarious form alter, making them more noticeable and more likely to form groups. These individuals organize into adult swarms that may fly far away to attack new places for food and hopper bands that march together as a group while eating. 


Unraveling the science behind Locust swarms in Africa 


Since 2018, desert locust swarms in Africa have decimated important crops and flora, especially in the Horn of Africa. Scientists have made alarming connections between this recent occurrence of climate change, and an increase in extreme weather.  


 Strong recent storms in the rapidly warming western Indian Ocean were related to the locust epidemics, with the resulting heavy rainfall, strong winds, and sodden ground making ideal circumstances for desert locusts to breed and proliferate. 


Another science behind locust swarms in Africa is cyclones happening more frequently and getting stronger. 2019 marked a record for the number of tropical cyclones in the Indian Ocean, with eight reaching landfalls, according to a 2021 commentary in the journal Nature Climate Change.  


Locust swarms in Africa are also brought on by flooding and heavy rains, which provide the insect more space to lay its eggs. Eggs are laid by adult females in rather open areas of damp soil. Early in development, the embryo needs water to develop. The embryos can develop and live without drying out if there is enough water available at egg laying. The embryo can remain in the eggs in this stage during the dry and chilly winter months until an increase in temperature causes hatching. 


Desert locusts are typically restricted to the semi-arid and arid deserts of Africa, the Near East, and South-West Asia and get less than 200 mm of rain yearly amid quiet times known as recessions. In typical circumstances, locust populations decline either naturally or as a result of migration but in the case of climate change, they are not declining.  


However, since the Industrial Revolution and especially 2009, the past five years have been hotter than ever. 20 of the world’s countries that are warming at the quickest rates are in Africa, according to studies linking a hotter temperature to more destructive locust swarms in Africa. Additionally, locusts multiply well in wet conditions. 


From October to December 2019, the Horn of Africa had prevalent, above-average rainfall that was up to 400% above average. The Indian Ocean dipole, a phenomenon made more prominent by climate change, was the reason for these unusual rains. 


Organophosphate pesticides are predominantly used by vehicle-mounted and aerial sprayers and to a lesser degree by knapsack and hand-held sprayers, to manage desert locust swarms. Pathogens and insect growth regulators are the present subject of a thorough investigation of biological control and other non-chemical control methods.


Since locusts can swiftly flee from most natural enemies, control by natural predators and parasites has thus far been relatively ineffective. Despite birds and humans frequently consuming locusts, this does not dramatically lower population numbers across wide areas. 

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