The plague of locusts in East Africa
It is now becoming evident that climate change has something to do with the plague of locusts presently ravaging the Horn of Africa. The crisis in that region is so Apocalyptic that it enjoys all the sights and sounds of the Book of Exodus, where God used a number of plagues to force the ancient Egyptian Empire to let the budding nation of Israel leave its borders into an uncharted search for nationhood. Just like in the children’s Bible storybook, the pictures are colorful, forceful and catastrophic. But in this case, certainly, the people of East Africa are not just seeing the picture, they are feeling the infernal pain.
The plague of locusts is spreading across the region, threatening the food supply of tens of millions. City-sized swarms of the dreaded pests are wreaking havoc as they descend on crops and pasturelands, devouring everything in a matter of hours. The scale of the locust outbreak, which now affects seven East African countries, is like nothing in recent memory. The locusts can travel up to 150 km a day, and a one-square-kilometre swarm can devour as much food as 35,000 people in a single day, according to the United Nations.
For Kenya, it is battling its worst desert locust outbreak in 70 years. Then, the infestation spreads through much of the eastern part of the continent and the Horn of Africa, razing pasture and croplands in Somalia and Ethiopia, and sweeping straight into South Sudan, Djibouti, Uganda and Tanzania.
The insects behind this pandemonium are known as desert locusts (aka schistocercagregaria), which, despite their name, thrive following periods of heavy rainfall that trigger blooms of vegetation across their normally arid habitats in Africa and the Middle East. This species threatens one-fifth of Earth’s land area and one-tenth of the global population. Over 60 countries are susceptible to swarms. Meanwhile, locusts in the solitary phase (that is, when they have not become gregarious in order to move in large swarms) occupy and breed in smaller regions. The last major plague, from 1986 to 1989, hit North Africa and the Middle East. Many swarms died while crossing the Atlantic; some reached the Caribbean.
Now,the climate connection is in rising sea temperature. Experts say a prolonged bout of exceptionally wet weather, including several rare cyclones that struck eastern Africa and the Arabian Peninsula over the last 18 months, are the primary cause of the locust invasion. The recent storminess, in turn, is related to the Indian Ocean Dipole, an ocean temperature gradient that was recently extremely pronounced, something that has also been linked to the devastating bushfires in eastern Australia. It may yet be a harbinger of things to come as rising sea surface temperatures supercharge storms, and climate change tips the scales in favor of circulation patterns like the one that set the state for this year’s trans-oceanic disasters.
In a National Geographic report, Keith Cressman, senior locust forecasting officer with the Food and Agriculture Organization,explained that the desert locust crisis traces back to May 2018 when Cyclone Mekunu passed over a vast, unpopulated desert on the southern Arabian Peninsula known as the Empty Quarter, filling the space between sand dunes with temporary lakes. Because desert locusts breed and reproduce freely in the area, this likely gave rise to the initial wave. Then, in October, Cyclone Luban spawned in the central Arabian Sea, marched westward, and rained out over the same region near the border of Yemen and Oman.
“Desert locusts live for about three months. After a generation matures, the adults lay their eggs which, under the right conditions, can hatch to form a new generation up to 20 times larger than the previous one. In this way, desert locusts can increase their population size exponentially over successive generations. Ultimately, the two 2018 cyclones enabled three generations of wildly successful locust breeding in just nine months, over the Arabian desert. Then the locusts started to migrate. By the summer of 2019, swarms were leapfrogging over the Red Sea and the Gulf of Aden into Ethiopia and Somalia, where they enjoyed another bout of successful breeding in subsequent months,” he expounded.
Interestingly, the East African plague reminds one of the 2003-2004 locust invasion in the Sahel, which also affected Nigeria, accentuatingthe climate change nexus. In the autumn season of 2003, FAO recorded four unrelated outbreaks which occurred simultaneously in Mauritania, Mali, Niger and Sudan. Shortly thereafter, unusually heavy rain fell for two days over a large area that extended from Dakar, Senegal to the Atlas Mountains in Morocco (some areas in Western Sahara received more than 100 mm of rain whereas they normally receive about 1 mm of rain in a year!). Consequently, ecological conditions remained favourable for at least six months and allowed several successive generations of desert locust breeding. In such circumstances, locusts increased very rapidly. By early 2004, the threat materialized as swarms of locusts started to form and move north into important agricultural areas in Morocco and Algeria, inflicting damage to crops.
By the second half of 2004, the FAO reported that a brief period of northeasterly winds had blown several swarms of the locusts out to the Cape Verde Islands, 450 km west of Senegal. The swarms contained up to 50 insects per square metre; and numerous locusts, tired out by the long flight, were found dead. Yet, Nigerian officials reported that swarms still found their flight path into three states in the northwest of the country, where they caused heavy damage to crops in some areas in Sokoto, Zamfara and Kebbi states.
Therefore, I am of the view that, because of the increasing impact of climate change on weather patterns, Africa should brace up and prepare for locust invasions. The preparation should involve a two-pronged preparedness: working closely with the regional and national Meteorological agencies; and spraying chemicals on identified areas before locusts can evolve from solitary to gregarious state.
In order to properly put this in perspective, it is germane to trace the structure of the desert locust’s life cycle. Always in search of food, solitary locusts are forced together during dry spells, when vegetation dies off and leaves minimal areas of green within the desert. Then, within hours of crowding, a boost of serotonin in the central nervous system of the locust spurs behavioral changes such as rapid movements, sociability, increased self-grooming, and a more varied appetite. This is the time that ecological factor kicks in, as returning rains provide moist breeding grounds. New generations form groups that forage in unison. Once their wings grow, the herds become flying swarms in search of more food and habitat. Although uncommon, a major plague begins when swarms, often travelling 30 to 60 miles a day, develop over multiple regions. Without intervention, plagues can last for years, until natural die-off occurs.
It is interesting to note that the switch to the gregarious state includes physical changes such as a larger brain and shorter legs. Transition to the gregarious phase also causes the brain – especially the midbrain – to grow larger, perhaps for more complex information processing (enabling them to work in a network). Offspring of gregarious locusts develop smaller femurs. Their hops are shorter but use less energy to cover the same distance.