------------------------------------------------------ URA 2055 ----------------
 Author(s) :
             THIOULOUSE J.,DEBOUZIE D.,BALLANGER Y.
             Structures spatiales et temporelles des populations d'un ravageur
             du Colza (Psylliodes chrysocephala L. (Col., Chrysomelidae)) dans
             plusieurs parcelles de culture
             Acta Oecologica - Oecologia Applicata
             Serial Number : 5, 1984, pp. 335-353
             ISSN : 0243-7678

 Key-Words :
             SPATIAL STRUCTURE,TEMPORAL STRUCTURE,POPULATION DYNAMICS,
             PSYLLIODES CHRYSOCEPHALA


 Abstract      Population dynamics of the cabbage stem flea beetle Psylliodes
             chrysocephola was studied in 1981 - 1982 in a village chosen for
             its relative geographic isolation : Saint-Thomas-en-Royans commune
             (Drome, France). No insecticide treatment was done. Seven winter
             rape plots covering an overall area of 5.6 ha were studied and
             sampled from September 1981 to June 1982 using a systematic grid
             map. Several observations were made at each point : number of
             adults drowned in yellow plastic basins or imprisoned beneath
             boxes, number of larvae in plants, number of nymphs in the earth,
             and number of adults emerging in the next generation. We have
             searched for spatial and temporal structures of the populations at
             two geographic scales: the plot and the commune (several km2). The
             great amount of data collected during this first year of study
             needs computer methods for storage (data base). Multivariate and
             non-parametric statistics and mapping methods lead to the
             following results: 1 ) spatial structures are observed within the
             commune (differences between the plots) and within some plots
             (gradients of infestation) ; 2) adult survival, calculated from
             October 1981 to March 1982, varies greatly from one plot to
             another, the highest value being five time larger than the
             smallest one: 3) larvae aggregate in some plants in the same
             intensity whatever their developmental stage; 4) among the 100.000
             adults that lived in October 1981 on the seven plots, 30.000
             survived in March 1982; the next generation emerging in june 1982
             is composed of 800.000 adults (+-150.000). From this
             methodological investment we propose mechanisms of the cabbage
             stem flea beetle infestations ; our hypotheses will be tested in
             the near future by observations in the same commune.

 E-Mail :    thioulou@biomserv.univ-lyon1.fr
             Laboratoire de Biometrie, Genetique et Biologie des Populations
             (URA 2055) - Univ. C. Bernard LYON I - 69622 VILLEURBANNE CEDEX