Measuring Behavior 2005: Griffiths

Laser marking carabid beetles for mark-release-recapture

G.J.K. Griffiths, L. Winder, J.N. Perry, C. Alexander, J.M. Holland, P. Kennedy, A. Birt and R. Preston

Plant and Invertebrate Ecology Division, Rothamsted Research, Harpenden, Herts., U.K.

Marking techniques (e.g. paints, fluorescent dyes, immunoglobin markers and drills) for mark-release-recapture studies are frequently limited either in their ability to provide unique identity codes or to mass mark a sufficient proportion of the population. A technique was developed to etch a unique 3-digit alphanumeric code on the elytra of carabid beetles using a 25-Watt CO2 laser (Fenix). The laser marking system enabled rapid mass-marking of carabid beetles with unique identity codes that were permanent and easy-to-read. The mark was applicable to a range of beetle body sizes, and could be applied in the field by establishing a generator-powered marking system in a transit van.

The technique was developed to examine the spatial distribution and individual movements of three carabid species (Pterostichus cupreus, P. melanarius and P. madidus) using mark-release-recapture across a grid of barriered pitfall traps in a winter wheat field. Distribution and dispersal of carabid species was examined in relation to spatial patterns and population growth of cereal aphid pests, a potential prey item. A Visual Basic programme was used to record information regarding species, age, sex and capture location of each beetle to be marked. The programme used this information to automatically allocate identity codes and to programme the species- and age-specific power settings and x-y co-ordinates for the mark via a windows based laser marking software WinMark Pro 5.1.

Scanning electron microscope images demonstrated that only the surface microsculpture of the elytra was removed and the laser did not penetrate into the structural component of the elytra. Comparison of marked and unmarked cohorts of P. melanarius and Nebria brevicollis in laboratory trials demonstrated that marking did not affect survival, probability of capture or encounter rate with pitfall traps. The project is being conducted with collaborators from the University of Plymouth, Rothamsted Research, Syngenta and The Game Conservancy Trust and is supported by the BBSRC.

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.