The interplay of rodent behaviour and semiochemistry: from scientific principles to control strategies

Commensal rodents are major pests of humankind. They have profoundly negative impacts through crop and food damage, carry human and animal diseases, cause allergy and asthma, and damage to the built environment. The costs of rodent infestations are difficult to quantify, but worldwide this runs to many billions of pounds. For example, food loss and damage caused by rats in the United States alone was estimated as $19 billion in 2000. In rice-growing regions, rodents cause annual pre-harvest losses of 5-17%: models suggest that a 5% reduction in rodent losses to the cereal harvest in undernourished countries could feed one third of all undernourished people worldwide. In the built environment, cable damage presents a significant risk of fire and electrocution, with costs of damage to infrastructure in the UK estimated around £200 million (2004). Rodents are also important in the spread of a large number of livestock and human diseases, including foodborne diseases; and contribute a significant source of allergens in residential areas that correlate with asthmatic symptoms. Current control strategies rely heavily on widespread and rather indiscriminate use of rodenticides, although the need for more integrated pest management approaches is increasingly recognized. Anticoagulant rodenticides (at least 90% of those used within Europe) are coming under increasing regulatory pressures due to persistence in the environment and negative impact on non-target species. There are growing problems of rodenticide resistance and public concern about humaneness. Thus, there are urgent needs to develop new control approaches, to significantly increase the efficiency and targeting of conventional approaches, and to develop alternative non-lethal approaches that increase the effectiveness, sustainability and humaneness of rodent control. Our goal is to develop new tools and strategies for rodent pest control, based on the use of scent signals (semiochemicals) to manipulate rodent behaviour. Rodents are critically dependent on scent cues for social communication, for the coordination of reproduction and reproductive investment, for navigation around the habitat and for predator avoidance. This provides the opportunity to manipulate such signals for control purposes, as has been developed very successfully for insect pest control. However, the complexity and individual variability of mammalian scent cues, combined with flexible and adaptive responses, demands a subtle integrated and interdisciplinary approach to understand the key components of signal and response and establish the potential for manipulation from a practical perspective. To achieve this, we bring together world-leading experts in wild rodent behaviour and chemical communication, the chemistry of volatile and protein pheromones, and the deployment of semiochemical-mediated strategies for pest control. The programme will focus on house mice and brown rats as the two most important rodent pests in the UK and worldwide, and will generate approaches that can also be translated to other rodent pest species. Our specific objectives are to * build a full understanding of the scent components that stimulate behaviours that have considerable potential for pest control; * understand scent deposits and signals and how these change with scent age, so that we can mimic them for pest control and use them to monitor infestations; * explore how to exploit the flexible learning that is typical of mammalian responses to scents; * test the ability of synthetic signals to manipulate key aspects of behaviour and reproduction in semi-natural environments. A stakeholder group comprising representatives of the pest control, environmental health and food industries, regulatory bodies, and scientific expertise of rodent pests in developing countries will ensure appropriate focus and provide pathways to the industries involved for subsequent deployment.