Many animals that communicate with sound time their calls in relation to their neighbors' calling and collectively produce various forms of synchronous or alternating choruses. Traditionally, these signal interactions have been described as cooperative events that serve to enhance species recognition, reduce attacks by predators or parasitoids attracted to the acoustic signals, or enhance the ability of a group to attract females. Alternatively, a few researchers have suggested that acoustic signal interactions represent some form of competition among individuals. Recently, Dr. Greenfield demonstrated experimentally and theoretically that synchrony and alternation in some sound-producing insects can be explained as by-products of jamming interactions between males competing to broadcast their signals to females. These findings were largely restricted to the experimentally ideal and simple situations of isolated pairs of signalers with comparable signaling strategies. Dr. Greenfield now will extend this work on jamming interactions by studying (1) how males in larger groups, such as found in most natural situations, control the timing of their signals, (2) whether or not individual males differ in how they jam neighbors' signals, and (3) whether or not the possible strategic differences between males depend on their energy reserves and/or the signaling of their neighbors. The orientation of females toward individual males in choruses will also be studied to determine how female choice may influence, and possibly be influenced by, male signal interactions. Dr. Greenfield's findings will provide critical information on neuro-behavioral timing mechanisms, the role of learning in signal interactions, and the complex interplay between female choice and signal-jamming competition between males. Because various sound-producing insects are agricultural pests, the behavioral information from this study may lead to improved control strategies via disruption of pair-forming activities.
