Measuring Behavior 2005: Goubault et al.

New techniques to detect and track chemical signalling during animal contests

M. Goubault, R.S.T. Linforth and I.C.W. Hardy

School of Biosciences, University of Nottingham, Nottingham, UK

Pairwise contests for indivisible resource are a widespread phenomenon throughout the animal kingdom. To avoid fights that may lead to serious injuries or the death of competitors, conflicts are often resolved by convention on the basis of asymmetries between opponents. Numerous studies have shown the importance of the asymmetries in fighting ability, ownership status and resource value on contest outcome. Such conventional contest resolution involves the use of signals or cues (e.g. visual, behavioral, olfactory or vibratory) that may be dificult for experimenters to identify and track. The study of chemical signalling has been particularly limited by technical constraints: chemical emissions are usually assessed by using Gas Chromatography – Mass Spectrometry (GC - MS) techniques a posteriori what do not allow determination of exactly when volatiles are emitted and thus whether releases are associated with specific behaviors.

We describe a novel technique that allows real-time tracking of volatile release by small animals: Atmospheric Pressure Chemical Ionisation – Mass Spectrometry (APCI-MS). This technique linked with GC-MS allows the identification of released compounds as well as subsequent determination of the exact time and relative quantity of volatile released, all in tandem with behavioral observations of unencumbered and intact individuals. We further describe a new method to chemically tag individuals in order subsequently to discern which of several interacting individuals emits each chemical signal.

We describe these results in the context of research into factors influencing contests for resources between adult female parasitoid wasps. These new techniques provide important opportunities for the study of chemical signaling during animal contests and other behavioral interactions.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.