The Horn of Africa is presently going through the worst desert locust invasion. Experts have predicted the locusts will stay at least until the end of this year, if not longer. The Kenyan government has made efforts to control the invasion. However, the methods used to rid the country of the locusts are doing more harm to the environment and people.
Despite the existence of alternative methods which have been proven to be efficient in controlling locusts, the government has continued to use chemical pesticides with high toxicity through aerial and ground application.
According to the Food and Agriculture Organisation (FAO), 193,000 litres of pesticides have been imported to date. At the onset of the invasion, very toxic pesticides were applied, such as fipronil, which has been withdrawn in Europe due to its high toxicity towards pollinators. The pesticides being used currently - mostly deltamethrin and to a smaller extent fenitrothion - are not only toxic to the locusts, but also to other insects, fish, wildlife and human health as well. Unfortunately, up to now, no monitoring study has been undertaken to assess the impact of these pesticides on soil and water quality, pollinators, wildlife and human health.
Another challenge that the government must be prepared to deal with is what to do with the unused pesticides once the locusts have been controlled.
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With such challenges, and due to the fact that the infestation will likely be in Kenya for a long time, it is critically important to consider long-term solutions. The government should develop integrated pest control strategies in order to protect people, non-target organisms (birds, bees, other important pollinators and mammals) and ecological processes to ensure food security and food safety. This strategy should also include all the available alternative methods and not only the application of chemical pesticides.
Mechanical methods include digging ditches to collect and bury hoppers as well as finding eggs and digging them out. These methods add on to biological and chemical control and have been proven to be effective, especially during an early infestation. The advantage here is that locusts can be used as fodder or food.
Perhaps more promising are the so-called biological control mechanisms. Natural predators such as wasps, birds and reptiles may prove effective at keeping small swarms under control. For managing more established swarms, newly-developed targeted microbial biopesticides, such as the fungus-based Novacrid, offer a larger-scale solution.
This fungus kills locusts and grasshoppers only, while other animals and insects are not affected. Despite its proven efficiency, it is still not registered for locust control in Kenya and only 400kg has been imported compared to 195,000 litres of conventional pesticides.
There is an argument that it is more expensive than conventional pesticides. However, with 1kg Novacrid you can treat an area 20 times more than when you use one litre of deltamethrin. Secondly, transport costs are lower, as you have to transport less and there are no external environmental and human health costs.
Other biopesticides which could be used in a combination with Novacrid are oils extracted from natural products. The oil extracted from the neem tree has been proven to control pests such as the fall armyworm.
The main active chemical in neem oil called “azadirachtin“, (with its highest concentration in seeds) is very effective in increasing mortality, in disturbing metamorphosis, and in reducing the general activity of locusts and grasshoppers. The neem oil can also be applied as a repellent since the locusts dislike its taste and smell.
Besides keeping the locusts at bay, the tree improves soil fertility and water holding capacity as it neutralises acidic soils. Its extensive root system also has a rare physiological capacity to extract nutrients from highly leached sandy soils.
The fact that the neem keeps its leaves during drought periods increases its importance as a source of biomass for mulching. The leaves used for mulching also act as a pH buffer, balancing acidic soils common in Kenya.
In a pastoral system, neem can have beneficial effects on the soil as well (moisture and nutrients status), provide shade, and improve fodder productivity in the dry season. Neem can also help in controlling more than 200 other pest species.
The ability of the tree to tolerate drought and saline conditions makes the neem tree a good option for land restoration. Currently, there is not enough neem oil available in the Kenyan market and it would be a great opportunity for farmers to produce this oil if government and development agencies supporting them.
Controlling locust swarms is no easy task. And the larger the swarms, the more difficult the task becomes. Prevention, then, is likely the best medicine, but this requires long-term thinking. Agroecology could play an important part in this by employing tactics such as inter-cropping.
Finally, the government and research institutions should invest in more research to figure out a sustainable long-term plan to empower affected farmers and pastoralists by providing them with skills in integrated pest management and prevention practices.
-Dr Bollmohr, an environmental scientist, is the Managing Director of EcoTrac Consulting. [email protected]