My work at Rothamsted has focused on characterising insect pheromones, generally low molecular weight lipophilic semiochemicals that enable individuals within a species to signal to each other. I was the first to identify sex and other pheromones in some insects for the first time, including aphids, mosquitoes and sandflies. Significantly, I showed that, for insect pheromones comprising mixtures of molecules, individual olfactory neurones in the insect were responding specifically to one particular component of this mixture. This led to the recognition that highly selective responses at single olfactory neurones are also the basis of host recognition. Plants give off many chemical signals or semiochemicals that can influence insect behaviour but individual neurones respond specifically to each, and host recognition is in response to activation of the appropriate neurones. In particular, I have shown that specific neurone activation is also the basis of rejection of inappropriate hosts, which are not necessarily the ones that do not produce the attractive chemicals. They may be the same species under stress producing other chemicals that activate different neurones and thereby elicit a repellent response that masks the attraction response. More recent work involves looking at similar responses between insects and vertebrate hosts. Cattle, for example, all produce attractants, but some additional compounds produced by certain individuals make them unattractive. The discovery that natural compounds released by some human individuals can reduce the level of attack by mosquitoes is a particularly exciting extension of these studies. I presented this new work on interactions between mosquitoes and human hosts at the Royal Society Summer Exhibition in 2006. With the underlying plant molecular biology in place, my work is already being exploited by European Community plant breeders with the future prospect of a new generation of genetically modified crops that are resistant to pests, diseases and weeds. In Africa, I have contributed to an innovative approach to controlling insect pests and parasitic weeds in cereals by means of specific companion croppings that is already responsible for raising the livelihood of poor rural communities from subsistence levels (www.push-pull.net).
After completing my BSc and PhD degrees at the University of Surrey and post-doctoral research at UMIST in aspects of organic chemistry, I started my professional career in natural products (now biological chemistry) with the Brewing Research Foundation. In 1976, I moved to Rothamsted Experimental Station (now Rothamsted Research) to lead a team working on agents with behavioural activity for new methods of pest control. I was appointed Head of the Insecticides and Fungicides Department (now the Biological Chemistry Department) in 1984, and continue very much to be personally involved with its day-to-day research activities in the UK and around the world. In addition, in 2007, I was appointed Director of the Institute's new Centre for Sustainable Pest and Disease Management. I am a Special Professor at the University of Nottingham, a position I have held since 1991, and have been an Honorary Member of the Academic Staff at the University of Reading since 1995.