New models could help African countries stop locust swarms before they start



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Several countries in East Africa, namely Kenya, Ethiopia, Uganda and South Sudan, are still trying to contain the worst desert locust invasion the region has experienced in more than 70 years.

The locusts have destroyed vegetation, especially staple grains, legumes and pastures, causing huge economic losses. The World Bank estimates that these losses could reach US $ 8.5 billion by the end of the year.

Unlike many other grasshoppers, the desert locust (Gregarious schistocerca) can change from a harmless solitary phase to a destructive gregarious phase in which grasshoppers (juveniles in their early stages, wingless) march together in bands.

Adults can fly and form giant swarms that can invade large areas far from their original breeding grounds.

Currently, countries are fighting the second generation (or wave) of locusts, as they have already reproduced and hatched once within the region. And reinfestation could continue if the environment encourages it.

The desert locust reproduces well in semi-arid areas. An ideal breeding site is characterized by warmth, nearby vegetation, and sandy soil with moisture and salt. Females usually lay their eggs 4-6 cm deep in the ground.

Governments have attempted to control these insects through a variety of efforts: from mobilizing military units to using youth as locust cadets.

But trying to control and eliminate flying locust populations is expensive and not very effective. The best option, proven by scientists, is to handle them at their breeding sites.

The eggs survive and hatch when environmental conditions are suitable; they can hatch in weeks or remain undeveloped for years. They are placed inside the ground, so they can be difficult to find; control measures, preferably biopesticides, are best used when locusts are on the surface in nymph or grasshopper form.

For this to happen, specific aerial and ground surveillance efforts to identify potential breeding sites are critical.

The most destructive locust swarm in East Africa occurred more than 70 years ago. The documentation of the information was very deficient, so there was no prior knowledge of the possible breeding sites in the region.

Together with my colleagues at the International Center for Insect Physiology and Ecology, I am trying to fill this gap. We have developed maps that predict where desert locusts might breed in Kenya, Uganda, and South Sudan.

Our model, backed by a machine learning algorithm, establishes a relationship between historical data from around the world on desert locust farms.

It also takes into account the climate and soil characteristics that are necessary for lobsters to lay their eggs and for the eggs to hatch.

Breeding sites can consist of between 40 and 80 million lobsters in one square kilometer.

Targeting these high-risk areas and strengthening ground surveillance is necessary to manage lobsters in a timely, cost-effective and environmentally friendly manner.

Risk areas

Using the model, we have identified and mapped possible desert locust breeding regions in Kenya, Uganda and South Sudan.

Vast areas in Kenya are at high risk because they have the right conditions to support lobster farming. These areas include Mandera, Wajir, Garissa, Marsabit, Turkana (all counties in Northeast Kenya), and some sites in Samburu County.

In Uganda, there are fewer possible breeding sites than in Kenya. These are restricted to the northeastern regions, specifically the Kotido, Kaabong, Moroto, Napak, Abim, Kitgum, Moyo and Lamwo districts.

South Sudan is at risk of breeding in the northern regions and the southeastern corner that borders Kenya. These sites exist in northern Bahr el Ghazal, Unity, Upper Nile, Eastern Equatoria, Warrap, Lagos, and some parts of Jonglei state.

Behavior

According to these predictions, ground and aerial surveillance efforts and monitoring of climatic and vegetation variables in the anticipated breeding regions should be significantly strengthened.

It will also be necessary to mobilize financial, material and human resources for the timely management of hopper belts when they arise.

We at the International Center for Insect Physiology and Ecology have several suggestions on what should happen next:

  1. Because there is a large area for possible locust breeding, a permanent locust monitoring unit should be established in Kenya. It should consist of ground and air surveillance teams, locust biologists, socio-economists, remote sensing experts, and weather and vegetation forecasters.

  2. A task force should be established in Uganda to collaborate with the Kenyan monitoring unit. Based on the overall coverage area of ​​desert locust breeding suitability in Uganda, it may not be necessary to invest in constant monitoring in the country.

    But the task force must work closely with Kenya’s locust monitoring unit and improve preparedness for potential outbreaks and swarms.

  3. Sustainable lobster management interventions and the associated mobilization of financial, logistical and human resources must be closely linked with strengthened lobster surveillance efforts.

  4. There should be a greater focus on sustainable and biological control options against locusts to mitigate the adverse impacts of the chemical pesticide-based locust control strategy.

    We believe that biopesticide applications should become a cornerstone in the management of locust outbreaks. Biopesticides need to be rapidly tested in the field in Kenya, commercialized and scaled up.

Finally, the current desert locust outbreak is triggered by a change in the rainfall pattern that expands the areas of possible invasion as a consequence of climate variability or change.

Other marginally suitable areas and conditions may be conducive to lobster farming in the future.

Therefore, it is important to intensify modeling efforts to understand the potential impacts of climate change on the current model predictions. The conversation

Henri Tonnang, Research Scientist, International Center for Insect Physiology and Ecology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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