12 February 2015 – Speaking at the Economist EventsÂ’ Feeding the World 2015 summit today, CABIÂ’s Dr Arne Witt talked about the impact that pests, especially Invasive Alien Species (IAS), have on food security and livelihoods. This yearÂ’s summit theme was ‘Quality vs quantity: food and nutrition security for nine billionÂ’. Participating in the panel on food loss and food waste, Dr Witt discussed the impact that crop pests have on pre- and post-harvest losses.

Most people in the developing world are active or employed in the agricultural sector; in some countries as many as 80% of the population. Invasive, non-native pests such as insects, diseases and weeds pose a significant threat to their livelihoods, impacting crop and pasture production, human and animal health, biodiversity, water resources and overall economic development.

The economic cost of invasive species is cause for international concern. Losses caused by invasives on just eight staple food crops at a global level cost US$12.8 billion per annum. In West Africa, the large grain borer alone is responsible for cassava losses of approximately US$800 million per year. The same beetle is responsible for maize losses in Tanzania of about US$91 million per year. The introduced weed, Solanum elaeagnifolium, contributes to a reduction in maize yields of up to 64% in Morocco.

At a global level about 40-75% of weeds in crop production systems are introduced; approximately 30-45% of mite and insect pests are alien, and anything between 65-85% of plant pathogens are non-native. IAS cost the global economy, in terms of impact and management, more than US$1.4 trillion each year – and this is just for the sectors we can measure or have data on. This figure obviously excludes the impacts of native pests, many of which have been moved within and between countries in a region. As such, at a global level, pests, on average, are probably responsible for a reduction in potential yields of anything between 20-40%.

In developing countries yield losses as a result of pests, both native and introduced, can on average be as high as 50%. In fact, some introduced pests such as the tomato leaf miner can result in no yield for the farmer at all if he or she has no means to manage it. In terms of pasture production some introduced invasives can reduce carrying capacities by as much as 90%. Millions of people in the developing world are dependent on livestock for their livelihoods.

Dr Witt pointed out that most farmers merely apply pesticides to combat these pests. This has implications for human health and biodiversity. At a global level we currently apply more than three million metric tons of pesticides. This results in more than 26 million non-fatal poisonings, thousands of fatal poisonings and hundreds of thousands of chronic illnesses such as cancers. A recent UN study estimated that illness associated with the use of pesticides would be in the region of US$90 billion between 2005 and 2020. Pests are also becoming resistant to insecticides and herbicides – more than 520 insects and mites, 150 pathogens and 270 weeds are already resistant. Access to markets is also becoming a serious issue. Between 2008 and 2012, 40% of fruit and vegetables exported to the EU were rejected, because of unacceptable pesticide residue levels.

Dr Witt called for more effective systems to be put in place to overcome some of these issues. Pesticide use can be reduced through the implementation of Integrated Pest Management (IPM) and Classical Biological Control (CBC). For example, the biological control of the cassava mealybug in Africa increased crop yields by more than 1.5 tons per hectare, while rice IPM in the Philippines resulted in savings of more than US$90 million in its first year of implementation, mainly as a result of reduced pesticide use. Biosecurity systems, similar to those being implemented by Australia and New Zealand, can help prevent new pest invasions. Biosecurity systems must be strengthened around the world, especially in developing countries, to help protect peopleÂ’s livelihoods and biodiversity.

Dr Witt also highlighted the importance of fully functioning, healthy ecosystems, which support the agricultural sector in terms of the provisioning of goods and services. He comments that, “We cannot provide enough nutritious food for a rapidly growing population in an unhealthy environment. If the impact of pests can be reduced by just a few percent, far fewer people on this planet will go hungry – in fact very few, if any, will go hungry. IPM and CBC are critical components of the future ‘green economy’.”

A free PDF copy of Dr Witt’s book is available to download: Invasive Alien Plants and their Management in Africa.

For all our latest news, click here.