The UN is warning of a “significant and extremely dangerous” upsurge in the breeding activity of desert locusts in East Africa, especially in Kenya, Ethiopia and Somalia, where the imminent second hatch of the destructive pest is threatening the food security of millions.

Crucial maize crops due to be harvested in March and April, and other staple food crops, are at risk as governments battle to contain a second wave of the insects and protect critical agricultural regions from infestation.

In Uganda, the government has warned the country to prepare for impending double disaster as unusually heavy seasonal rains are expected. A Christian leader explained to Barnabas that the severe rains will increase the risks of a locust plague. “Locusts are going to have soft ground under which breeding is going to triple. As locusts increase, the danger towards destruction of both food and pasture will also triple. If there are no measures to mitigate the awaited calamity, people’s lives will get destroyed by hunger,” he warned.

Desert locusts are usually restricted to the semi-arid and desert regions of the African Sahel, the Near/Middle East and parts of south-west Asia. This area, of about 16 million square kilometres, comprises around 30 countries, including some of the world’s poorest nations.

A second wave of this year’s devastating locust outbreak is under way in summer breeding grounds in East Africa, parts of the Middle East and south-west Asia. Breeding conditions for the locusts have remained highly favourable since February along both Red Sea coasts and in East Africa. Heavy rains fell in southern Iran spurring egg laying. Western Africa, where dry conditions have dominated, remains largely unaffected by the locust swarms.

In Kenya, one of the worst affected countries, hopper bands (groups of immature insects) and immature swarms are multiplying in the northern and central counties. Aerial and ground control operations are underway in Marsabit and Turkana, where a high concentration of locusts remain. Swarms are also crossing from Somalia, where at least one mature swarm is already mobilising.

Similar breeding patterns are being observed in south-west Ethiopia, Sudan, Eritrea, Saudi Arabia, Kuwait and the UAE. In Iran, eggs laid by swarms in the south-west are due to hatch and form into hopper bands this week and adult swarms may soon cross the border into Pakistan.

Within south-west Pakistan’s agricultural belt, extensive egg laying is already happening. New generations of hopper bands and small swarms are expected to emerge across Baluchistan province by the end of March. New swarms are also forming in the north-west of the country.

How does a locust plague develop?

Desert locusts (Schistocerca gregaria) are large grasshopper-like insects. Typically solitary and sedentary, the species morphs into its gregarious form if population density increases. Heavy rainfall in arid regions of the Sahel and North Africa brings rapid growth of lush vegetation for locusts to feed on and increases the risk of swarms developing.

Within six hours of eggs hatching, if the juvenile locusts are crowded together, their bodies and brains will literally mutate genetically to initiate gregarious behaviour. Solitary insects are green but change to a yellow colour in the gregarious form.

The young locust nymphs march in synchrony as they form dense hopper bands. The hoppers shed their exoskeleton repeatedly as they pass through several growth stages, called instars, before maturing into highly-mobile winged adults. Mature swarms, of hundreds of millions of locusts, can migrate distances of around 150km a day, and even 200km when aided by prevailing winds.

In the first wave of the current plague, locust swarms were reported to have migrated from the desert of Oman into Yemen and across the Red Sea in late 2019. The swarms spread across East Africa, resulting in the worst outbreak seen in 70 years. Millions of locusts also entered into Pakistan’s agricultural belt, via Iran.

The gregarious phase is transferred from mothers to offspring which means that the second wave of a plague, as is now facing East Africa and south-west Asia, can be many times larger than the first. Soft damp soil is especially favourable for egg laying and the current rainy season in East Africa is providing ideal breeding conditions in many regions.

What control measures are being taken?

Aerial insecticide spraying, mainly with organophosphate chemicals, is the only effective means currently available to contain large-scale pestilent swarms. The key focus of control operations is to halt the breeding cycle by destroying the hoppers before they mature into adults.

Ground monitoring to identify breeding zones at an early stage is critical, so that governments can effectively target aerial spraying. Scientists are using supercomputers and climate data to predict where and when egg laying and breeding surges will occur.

The cost of effectively controlling the plague is estimated to be around $60m (£47m). If the current breeding upsurge is not contained, costs could soar to as high as $500m (£393m).

The last locust plague, in 2003, which affected 23 West African countries, involved three generations and took two years to bring under control.

What is the impact of a locust plague?

A desert locust plague has the potential to damage the food and economic security of a tenth of the world's population.

The desert locust is considered the most dangerous migratory pest on earth. A swarm of only one square kilometre will eat as much as 35,000 people can eat in one day. In times of plague, desert locusts can spread across around 29 million square kilometres – extending to around 60 countries – or more than 20% of the total land surface of the planet.

Many thousands of people were already in the grip of food shortages, due to either drought or flooding in the last twelve months, before the crop destruction caused by a first wave of vast swarms of desert locusts in East Africa and Pakistan earlier this year.

Experts warn that a 400-times increase in locust numbers could occur in this second wave of breeding if current control efforts fail, and the UN has stated that 20 million people are now facing the threat of severe food insecurity in the Horn of Africa.

From Barnabas Fund contacts and other sources