Basically, what happens is when the breeding conditions improve, they start laying more and more eggs in the sand. They like wet, sandy soil. What happened over the last few months leading up to the first swarms in December and at the beginning of this year was that we had an extraordinary amount of rainfall.
Even in what was supposed to be our dry season, we were getting a lot of rain. So, all of these dry, arid areas, desert areas, and semi-desert areas were switched from totally dusty to being full of vegetation and grass so the locusts had a lot of places to lay eggs.
Those eggs hatch and as the numbers increase, the density of them together, and the physical contact of them all together triggers an epigenetic switch that actually changes them from solitary animals to this gregarious creature. One thousand are males and 1, are females.
If 1, females lay eggs and each female lays eggs then that continues, then very quickly you end up with millions and billions and trillions. Another other option is to spray the hoppers. But as the number goes up, the more unfeasible it is.
My sense is that there are also a lot of natural things that are catching up with the locusts, whether that be predators, parasites, and things like that. When they came through Mpala, for instance, I saw migrating European storks — the white storks — feeding on the locusts as they came through.
If we do it badly, we could end up killing all this other biodiversity. Department of Agriculture, and many others to see if we can sequence the locust genome. One remarkable thing about the locusts is they appear to have a very large genome.
There are many different aspects of locusts the genome could help us understand. We could get a better understanding of some of the physiology and biology. For example, it could help us understand the switch that occurs in them from being solitary to gregarious. My real interest in looking at the locusts is how are they part of the wider ecology and landscape and that question of how we respond to them.
Right now, we use pesticides and chemicals to respond, as I said. Locusts do not attack people or animals. Swarms of desert locusts are threatening large areas of pastures and crops, overwhelming countries in the Horn of Africa, the Middle East, and South Asia. The crisis has affected 23 countries to date, from Pakistan to Tanzania.
In the wider East Africa region, the above average rainy season in March and April created favorable conditions for locusts to breed — increasing their number and the areas they could spread to. If left unchecked, the number of desert locusts could grow by times by June, as each generation has a fold increase in population on average.
Within the region, 24 million people are food insecure and 8 million are internally displaced. The locusts further threaten their food security and their ability to access pasture for livestock.
This locust invasion coincides with the long rainy season and comes at a time when farming communities are preparing to harvest their crops between the months of March and April. The current situation could affect their livelihood and their means of survival in the coming months. The impact on communities is also likely to be long-term, affecting their ability to rebuild savings, regrow crops and livestock, and to weather future shocks.
The outbreak is evolving quickly. A recent joint impact assessment report by the Government of Ethiopia and FAO estimates that the desert locust outbreak in Ethiopia alone has caused , metric tons of cereal loss, along with destruction of , ha of cropland and 1,, ha of pasturelands, with more than 1 million Ethiopians in need of food assistance as result. By itself, the COVID pandemic has the potential to create a severe food security crisis in Africa, as elsewhere, as agricultural production contracts and food imports decline.
Yemen, ravaged by war, no longer had the means to deploy the specially trained crews that spray common pesticides that kill the insects in a matter of hours. Then, catastrophically, heavy rains hit the country, providing yet more breeding opportunities for the invading locusts. Early last summer, the plague jumped the gulf and landed in Somalia, then continued its march into Ethiopia and Kenya. In an ideal world, Cressman and his colleagues would catch and quash the threat early.
They can project where the locusts might head over a month ahead of time, and alert those countries to mobilize their forces—distributing pesticides from a central repository, prepositioning aircraft for aerial control operations, and readying the professional locust hunters.
No problem. Once the pesticide operation begins, people occupying infected lands have to vacate for 24 hours until the chemicals break down.
A new biocontrol method, though, is showing promise, says Cressman: The killer fungus Metarhizium acridum , which only torments locusts and grasshoppers, could more selectively target the menace. They need a lot of vegetation to fuel their swarms, and that requires rain. The highly active cyclone seasons the past few years may be a sign of things to come. Each generation, on average, sees a fold increase in the population. The growing swarms spread to new areas, disrupting the food supply, upending livelihoods and requiring substantial resources to address.
The economic, human, and environmental impacts of the current locust plague are substantial and could last generations. When affected households and families struggle to meet basic needs such as food and shelter, nutrition, health care, and education may be neglected, hindering long-term health and development, especially of children.
Studies of past locust plagues found a notable decrease in school enrollment in affected areas as well as evidence of stunting in infants and children. Decimated crops and pasture mean that food security and livelihoods for millions of people—especially in countries marked by fragility, conflict and violence—are at stake.
The Greater Horn of Africa already has a large vulnerable population. As the locust upsurge began to set in, o ver 23 million severely food insecure people and over 12 million forcibly displaced were already in the area. Yemen, given its prolonged conflict, had an additional 24 million people in need of assistance at the start of the locust outbreak. Climate change is a key driver of the current locust upsurge. One of the strongest Indian Ocean Dipoles in 60 years fueled a stretch of unusually wet weather, including several rare cyclones, that struck the Arabian Peninsula and then eastern Africa in the 18 months prior to the locust outbreak.
This triggered excessive vegetation growth that supplied plenty of food for the locust population to explode and swarm.
Rainfall totals that were about mm above average in East Africa in the autumn of enabled locust populations to move far and quickly into that region.
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