Croonian Prize Lecture
Professor John Pickett FRS, Rothamsted Research
Organisms of all kinds use signals comprising minute amounts of natural
chemicals. Whether these are pheromones involved in developmental regulation
and sexual interactions, or other types of chemical signals (semiochemicals)
that relate to interspecific interactions including germination cues or food and
host attractants, such semiochemicals potentially provide new chemical tools for
managing pest and beneficial organisms.
The exploitation of semiochemicals is demonstrated with dramatic success in
the management of pests and parasitic weeds in resource-poor East African cereal
farming. However, the underpinning science extends to intensive agriculture and
also to animal husbandry and human health. There are common features of
semiochemically mediated communication that determine both positive cues, such
as those involved in seed or spore germination and reproductive site, food or
host location, but also inhibitory processes and the avoidance of inappropriate
members of a potential host range. Not only can these types of semiochemicals
be used to "push" and "pull" the behaviour or development of pest and beneficial
organisms, but they may, by relating to biotic stress, also be used to "switch
on" defence at earlier stages prior to attack by a pest, pathogen or parasitic
weed. These same stress-related semiochemicals are available for capturing the
benefits of organisms antagonistic to pests.
To understand and exploit semiochemicals, a truly multidisciplinary approach
comprising highly sensitive chemical, spectroscopic, electrophysiological and
molecular biological approaches is exemplified.