As climate change increases the risk of pests and diseases, can innovations increase farmers’ resilience to this threat?

Liz Ng'ang'a

Three approaches for better pest management

Due to their cold-blooded nature, insects must live in areas with temperatures that are suitable for their biological processes; for instance development, reproduction and survival. Climate change is therefore expected to profoundly impact insects, including their physiology, their physical features and their behaviour, particularly their relationships with other species. As a result, immense shifts are predicted in the population dynamics, abundance and geographical spread of insects. In turn, these alterations will have positive and negative outcomes for people, livestock and crops, in terms of vulnerability to insect-transmitted diseases, and availability of the essential services provided by insects, such as pollination and pest regulation. 

Amidst this scenario, icipe’s goal is to support communities to not only adapt, but to thrive regardless of the impact of climate change, especially in relation to insects. The Centre’s approach can be summed up in three thrusts (though this list is by no means exhaustive).  

1. Re-assess and re-innovate 

icipe is re-assessing the performance of its existing strategies against climatic change, and re-innovating them accordingly. One example is the development of a climate-smart version of the Centre’s highly successful push-pull technology, which addresses the key constraints of cereal-livestock mixed production systems in Africa including: insect pests like stemborers and fall armyworm; the parasitic weed Striga (and other weeds); maize ear rots and mycotoxins.  

The push-pull technology works by introducing foliage around crop fields to distract, or pull, pests away from produce, while at the same time intercropping repellent (companion) plants into the field to ward off, or push, pests away from crops. Greenleaf desmodium has proven to be an effective repellent of fall armyworm, and Napier grass is often used as foliage to entrap fall armyworm eggs. 

Using the push-pull technology also improves soil health and provides high quality fodder, since the companion crops are superior forages. Developed over the past 7 years, the climate-smart push-pull technology has been shown to enable farmers living in some of the regions in Eastern Africa most severely affected by climate change to stabilise their cereal-livestock production, while more than doubling yields.  

2. Knowledge generation 

icipe is conducting research to generate new, innovative technologies and strategies with regard to insects and climate change in Africa. A major proportion of these studies have been conducted through the Climate Change Impacts on Ecosystem Services and Food Security in Eastern Africa project implemented by icipe, the Ministry for Foreign Affairs of Finland, and various partners from 2011-2015.  

The researchers investigated how current and projected climate change scenarios will affect key pests and diseases, as well as beneficial insects, of four important crops: maize, crucifers, avocado and coffee, around Taita Hills (Kenya), Mount Kilimanjaro (Tanzania) and Jimma Highlands (Ethiopia). The pests studied were maize stemborers (Busseola fusca and Chilo partellus); the diamondback moth (DBM), which damages crucifers; and fruit flies (specifically Bactrocera dorsalis), the false codling moth (Thaumatotibia leucotreta), and thrips (Heliothrips haemorhoidalis) in relation to avocado. The coffee pests studied include the variegated coffee bug, Antestiopsis thunbergii, and the coffee white stemborer, Monochamus leuconotus. 

The findings showed that, due to rising temperatures, higher altitude areas will become more suitable for the pests listed above and, as a result, their damage on crops will increase significantly. However, the studies revealed that although temperature is a major factor, other climatic elements (e.g. rainfall), responses of natural enemies to climate change, soil status and issues related to human activity (e.g. environmental degradation), are also playing a role. 

To minimise the predicted risks, suitable natural enemies for the control of stemborers B. dorsalis and DBM, are being released at different altitudes. The Centre is also promoting conservation of wild crucifers, which provide alternative refuge for DBM, to naturally control the pest in high altitudes.  

3. Risk analysis tools 

Using remote sensing approaches, icipe is also developing risk analysis tools for climate change, including pest distribution maps and prediction models. For instance, using geospatial tools, the researchers have collected data on four key pests that carry bee diseases in Kenya, which could enable them to map the high-risk areas and introduce quarantine measures to reduce the spread of disease. 

The Centre has also developed a new remote sensing-based methodology to map flowering plants in Africa, and used it to produce the world’s first floral map. Long-term data on flowering patterns in a given landscape helps to understand, among other factors, the climate and ecological stresses that trigger pests and diseases in bee colonies. This information can also be used in evaluating the effects of pollination and the quantity and quality of beekeeping products.  

The Technical Centre for Agricultural and Rural Cooperation (CTA) is a joint international institution of the African, Caribbean and Pacific (ACP) Group of States and the European Union (EU). CTA operates under the framework of the Cotonou Agreement and is funded by the EU.