Rodents, especially rats and mice, have been a known public health threat for centuries and are emblematic of poverty, underdevelopment and epidemics. They attack and damage crops grown in the field, as well as damaging stored crops in homes, warehouses and factories, effectively damaging and contaminating food across all production value chains. Rodents cause problems in cities, where they feed on human refuse, damage sewage and drainage systems, undermine foundations, damage electrical wires and gas supplies and can terrorise citizens by entering people’s homes and even biting people. There have been increasing case numbers of serious diseases linked to rats, including plague, Lassa fever, hantavirus, leptospirosis, typhus, toxoplasmosis, babesiosis, Lyme disease and leishmaniasis. With rodents transmitting more than 60 diseases to people and domestic animals, damaging food production systems, and exacerbating sanitation problems, few would argue society’s rodent problems have been solved.
Despite this, rats and mice are arguably one of the most neglected pest problems the world over, and there has been relatively little global research on rodent pest management since the advent of anticoagulant rodenticides in the 1950s. Although some of these poisons can work very well, their usage is increasingly challenged because of their damage to human health and the environment. In particular, indiscriminate large-scale use of rat poisons is known to drive biodiversity loss and such changes can lead to outbreaks of zoonotic diseases. The commercial private sector continues to advocate the use of poisons and is currently doing little to develop alternative rodent management technologies. Safe and effective use of poisons requires extensive training, whilst many poor communities say rat poisons are ineffective, unaffordable or unavailable. Ultimately many poor families resort to highly toxic and illegal substances for rat control. The poor application of rodenticides often results in treatment failures, leading to apathy and widespread acceptance of rodent pests in the environment. Many poor communities suffer from low awareness and ingrained defeatism when trying to control rodents and therefore acquiesce to rodent damage.
What is NRI's solution?
NRI research has sought to develop alternatives to poisons with a view to developing safer and more sustainable methods of rodent control. For example, funding received through DFID brought the institute together with researchers from China and Tanzania to develop fertility control of rodent pests. Fertility control has long been argued to be more ecologically sustainable, more cost-effective, more humane and more effective than mortality control using poisons. This research led by the institute has resulted in commercialised products in China, which are now in the final stages of being registered in Tanzania and other East African countries. The use of fertility control has been shown to have no adverse environmental impacts and particularly works well to regulate population outbreaks of rodents, reducing their numbers and subsequent crop damage and disease impacts. The institute’s research has also increased our understanding on the role of predation to control rodent pests, such as understanding the landscape of fear created by predators of rodents and how the smell of predators can be used to repel rodents from food storage areas.
Innovations and outcomes
Developing a paradigm of ecologically based rodent management to reduce the impact of rodents on human health and agricultural production has resulted in dozens of high-impact research outcomes published in peer-reviewed journals, as well as leading to changes in actual rodent management practice. Understanding of rodent biology and ecology and human behaviour has led the institute to provide advice, training and guidance to the World Health Organization, the UN’s Development Programme and the World Food Programme, and many NGOs involved in development assistance and the private sector. For example, research in South Asia helped stop a famine caused by unusually high rodent numbers by providing factual, science-driven advice and management tools to national and international assistance programmes responding to rodent outbreaks caused by synchronised bamboo masting events.
Research in Africa has led to tangible improvements in government sanitation programmes and educational standards for pest control operators. The WHO has relied on the institute to provide advice to national governments, particularly the Government of Madagascar during recent plague outbreaks, and to provide training on rodent biology and management to plague-endemic countries across Africa and the world.
The institute’s research has facilitated global capacity building in over 30 universities, research institutes and development organisations on alternative methods of rodent control including non-chemical control methods based on innovative trapping methods, the development of fertility control and the use of biological control through optimising natural predation, all of which has been carried out in collaboration with communities affected by rodent pest problems. Through the institute’s work, these communities have realised that they need not just accept the problems rodents cause to their livelihoods, and that it is possible to control rodents once armed with the right knowledge and tools. The institute’s work in Africa to build research capacity has had great impact, and a new generation of rodent experts continues to be built through its research project activities that have trained at least 50 Masters and PhD students across Africa over the past 10 years. Outcomes offering high-tech solutions and more applied research to optimise traditional rodent management practices have contributed to solving one of the world’s most intractable pest problems through more ecologically sound rodent management that enhances food and nutrition security whilst protecting the environment. Development of alternative rodent control technology is helping to reduce the use of poisons that are dangerous to humans, other animals and the environment, promoting One Health principles of healthy environments, healthy food and healthy people.