Original Contribution by Sharmin Sultana
Seeing a locust, one cannot imagine that a harmless member of the grasshopper family can become one of the world’s most devastating pests. Yet, in 2020, within just a few months locust swarms destroyed more than 1.2 million hectares (ha) of crops and pasture in a region where people were already hit by droughts, floods and conflict. In general locusts swarm in different parts of the world. However, since mid-2019 they have been active across the Arabian Peninsula and East Africa, pushing more than 20 million people at risk of hunger.
Around 23 countries: 9 in East Africa, 11 in North Africa/Middle East and 3 in South Asia have been affected by locusts and face an unusual threat to food security and livelihoods according to a World Bank report. The UN Sustainable Development Goals list locusts as one of four threats to world food systems. An adult locust eats roughly 2 grams of food daily. As a result, a large swarm eats enough food for 81 million people, equivalent to 1.8 million metric tons (MTs) of green vegetables.
According to reports by international aid agencies, the most recent locust swarms (2019–2021) caused 356,286 MTs of cereal loss along with wasting 197,163 ha of cropland and 1,350,000 ha of pasture-lands in Ethiopia alone. As a result of this one million Ethiopians required food assistance due specifically to damage from locusts, prior to the start of its civil war in late 2020. Around 20.2 million people in Ethiopia, Kenya, Somalia, South Sudan, Uganda, and the United Republic of Tanzania faced severe acute food insecurity, exacerbated by these locust infestations.
These locust swarms formed in the regions of East Africa, the Arabian Peninsula, and the Indian subcontinent. According to the United Nations Food and Agriculture Organization (FAO), these swarms were the worst plague in Kenya in 70 years; in India in 26 years; and in Ethiopia and Somalia in 25 years. They spread throughout counties within Kenya, Ethiopia, Uganda, Somalia, Eritrea, India, Pakistan, Iran, Yemen, Oman, and Saudi Arabia. Usually, the reason for the quick spread of the swarms from one country to another is wind patterns. In this case, southeast monsoons blew in from the Indian Ocean to Kenya and carried the locust swarms to other countries. Specifically, Cyclone Mekunu in 2018 and the warm weather after heavy rains are thought to be the reasons for this particular outbreak.
Previous locust outbreaks in Africa from 2003-2005 led to an estimated $2.5 billion in crop damage. Depending on the cultivating seasons, they can destroy from 50 to 80% of crops. The potential hunger threat is huge in a region where millions of people are already facing chronic food insecurity. The impacts could threaten livelihoods, savings, and push vulnerable people further into poverty.
Typically, locusts are solitary pests. However, in special environments, they become gregarious. The serotonin hormone in their brains is responsible for this transformation. This transformation changes not only their body color and size, but also their behavior. As a result, they congregate in groups instead of staying solitary. This is how they enter the swarming phase, where they become migratory, traveling from one place to another and consuming huge amounts of crops on their way.
Locusts thrive after heavy rainfall and an abundance of vegetation. Locusts breed after rainfall because they need moist soil to lay their eggs and an abundance of food for rapid growth. Even a small swarm of one square kilometer holds 80 million locusts and eats the equivalent of enough food for 35,000 people in one day. The swarms in east Africa in 2020 may have included a trillion locusts by some estimates.
Types of Locusts
Different parts of the world have different species of locusts. The desert locust (Schistocerca gregaria) is considered the most dangerous of all migratory pests because of its ability to reproduce quickly and destroy crops, pasture, and fodder. They are found in more than 65 countries of Africa, Asia, and the Middle East.
Migratory locusts become swarms in Africa, Asia, Australia, and New Zealand. In the 1930s, the High Plains locust was found in the American Midwest but is rare now. The Rocky Mountain locust was once one of the worst insect pests but it became extinct in 1902. Thus, North America and Antarctica do not have any locust species. The Senegalese grasshopper and the African rice grasshopper often show locust-like behavior.
History of major infestations
In the last two millennia desert and migratory locusts continued to appear at irregular intervals as outbreaks in Africa, the Middle East, and Europe and destroyed crops and caused famines which led to human migrations
In Kenya, one of the largest swarms was recorded to cover 10,000 square kilometers. According to the Bible and the Koran, humans were victims of locust swarms that appeared from nowhere to darken the skies. Though the swarming behavior decreased by the 20th century, swarm formations can still be present.
In 1988, swarms originating in North Africa traveled to the Caribbean and South America, and amazingly crossed the Atlantic Ocean. Locusts easily move across countries in a matter of days. They routinely cross the Red Sea, which is a distance of almost 200 miles.
Challenges in control measures
- Not having enough aircraft to spray appropriate chemicals on the pests.
- Problems in maintaining supplies of these chemicals and pesticides.
- Political instability: for instance, ongoing war has made Yemen or Ethiopia increasingly inaccessible to humanitarian assistance, which has slowed down outbreak response; furthermore, Yemen does not have funds for specially trained crews to spray pesticides that kill the insects.
- Natural disasters make the breeding areas difficult to access.
- Unpredictability in movement makes it harder to maintain funding, political will, and capacity building initiatives.
- Lack of coordination in the efforts of neighboring countries.
- Large logistical requirements to combat an infestation over a vast area; moreover, due to ongoing COVID-19 restrictions, supply chains have been hampered.
What can aid agencies do in response?
- Forecasting is the best preparation for future locust swarms. Forecasting weather variations, wind speed and direction, temperature, and humidity can help to determine the movement of locusts and gives farmers time to start spraying early. Also forecasting can predict regions that are likely to suffer from locust plagues in the near future. Tracking locust migration patterns and overseeing regional response efforts are necessary. Using modern technologies including tools such as GPS (global positioning systems), GIS (geographic information systems) and satellite imagery for forecasting and tracking is part of a vital response to this threat.
- The most effective way to fight outbreaks is using chemical insecticides, which can be distributed using packs on the ground, or by aircraft. However, the substances used can be harmful to the environment and to human health.
- Biological pesticides are another option. Fungus-based pesticides are thought to be harmful to a much narrower range of species. However, bio-pesticides do not work as quickly as chemical sprays, and this threatens greater crop damage.
- Drones and electrified metal grids can be used to control locust swarms. Drones can help spray chemicals and provide surveillance. Electric grids can be dragged over fields to generate vibrations in open fields to kill and deflect the insects.
- Changing agricultural practices may also be effective. Instead of relying on traditional crops like maize and cowpeas, investing in fruit and vegetables can deter locusts. An initiative taken by village irrigation projects of Action Aid Kenya in 2009, in partnership with selected farmers, is one example.
- Locusts are edible and have been eaten throughout history, and may be consumed as food. Locusts are eaten in the Arabian Peninsula and Africa. In Saudi Arabia, the consumption of locust spikes around Ramadan since those are believed to be healthy. Some popular ways of eating locusts are fried, smoked, or dried. However, the use of pesticides can make them unsafe.
Climate change, sea-level rise, and cyclones can all bring extreme rainfall, which enables locusts to hatch and breed. For example, in the Arabian Peninsula, a heavy rain produced higher vegetation growth which then triggered locusts. Locusts are also highly adaptive to heat and drought. Deforestation and environmental degradation can also create ideal conditions for more locusts to breed. If we want to save ourselves from locust swarm attacks, we have to pay attention to our environment. Failing to tackle the climate crisis might cause more frequent and devastating locust outbreaks, and may result in more hunger and food insecurity. Hunger and food insecurity are key barriers to sustainable development. Therefore better control of locust destruction of food crops is essential if we are to achieve the status of Zero Hunger (i.e. the second UN Sustainable Development Goal).
Sharmin Sultana is a public health communication professional with an MPH in community nutrition. She has been a USAID fellow and has worked in nutrition, food security and social and behavior change communication projects in Bangladesh.