ECOPHYSIOLOGICAL AND ENZYMATIC VARIABILIT Y OF CYDIA-POMONELLA L ACCORDING TO GEOGRAPHICAL ORIGIN AND HOST-PLANT

Simultaneous ecophysiological and enzymatic investigations were perfor med on,Cydia pomonella populations from distant areas and from various host plants (apple, pear, quince, walnut and apricot). Different phot operiodic thresholds for diapause induction and temperature thresholds for post-diapause reactivation were observed according to areas but n ot host plants. The enzymatic analysis of 7 polymorphic loci exhibits only a weak genetic differentiation between populations from different localities (F-st = 0.0294) and different host plants (F-st = 0.0385). However, significant differences of allelic frequencies were noted. W e put forward the hypothesis of local populations, mostly apple pests, some of which emigrate to occasional hosts, according to spatio-tempo ral synchronisms. Nonetheless, this dispersion does not constitute a ' foundation effect', since arrested winter development and the non-coin cidence of the sensitive phenological stages of host-plants lead to a regular mixing of subpopulations.