|Greenstone, Matthew - INSECT BIOCONTROL LAB|
Submitted to: Ecology of Predator-Prey Interactions
Publication Type: Book / Chapter
Publication Acceptance Date: July 2, 2004
Publication Date: July 10, 2005
Citation: Greenstone, M.H., Dickens, J.C. 2005. The production and appropriation of chemical signals amount plants, herbivores and predators.. Ecology of Predator-Prey Interactions., p. 139-165. Interpretive Summary: Plant-eating insects, the plants they live on, and the predators that attack them all use chemicals signals to communicate. The insects may originally have emitted the chemicals in order to find food, attract mates, or warn of danger, but over time the plants and predators have appropriated these signals for their own uses. For example, predators use prey insect sex pheromones to find and attack them, and plants emit chemicals to attract predators to feed on insects that are attacking the plants. The insects then evolve new strategies to avoid attack, for example by subtly changing the pheromone to prevent a predator from detecting it. This kind of cat-and-mouse arms race is called coevolution. We review this literature in order to discern broad patterns in the evolution of chemical communication and suggest future research directions. We found that pheromone coevolution is extremely widespread among agricultural and timber pests, their host plants and predators, but has not been well studied in other situations. We note that coevolution does not go on indefinitely, but is constrained by the likelihood of insects and their predators being found in the same place at the same time, and may also depend upon whether other means of signaling, for example with color, may be more advantageous. We suggest that investigators develop testable hypotheses on when chemical signaling will be found, and study specific situations that have not been studied but are especially apt to offer clues to pheromone coevolution. These results will be useful to evolutionary biologists, ecologists, and chemists, and to applied entomologists seeking new strategies to control insect pests by manipulating their behavior with pheromones.
Technical Abstract: Predators and prey are subject to stimulation by chemicals produced by themselves and by plants in their environment. Prominent among the plant chemicals that mediate predator-prey interactions are prey-induced chemical cues that alter predator physiology and behavior. However, interactions among plants, prey, and predators also are shaped by a complex blend of perceived interspecific chemical signals (allomones, synomones and kairomones) and intraspecific chemical signals (pheromones). The capacities and constraint of sensory receptors and underlying physiological processes determine the output of predator-prey communication and the subsequent behavior that describes how they interact. For example, prey-damaged plants produce chemical cues not present (or present in higher concentration than) in undamaged plants, while prey and predators produce alarm pheromones, as well as marking, sex, and aggregation pheromones. For plants, prey, and predators there are tradeoffs in producing these compounds. Thus, synomones may act synergistically with prey pheromones to increase the attraction of aggregation pheromones, and aggregation pheromones of prey may act as kairomones for predators, increasing their risk of predation. In this chapter, we explore the intricate and sometimes constrained interplay among sensory, physiological, and behavioral components of predator-prey interactions.