INFLUENCE OF THE IMMEDIATE ENVIRONMENT ON THE DISPERSAL OF SITONA-LINEATUS L. (COL., CURC.) DURING CROP COLONIZATION

The factors favouring the colonisation of pea fields by Sitona lineatu s L. were studied in three trapping experiments in fields of the ITCF Experimental Farm in Boigneville (Essonne, France). One trapping devic e was placed in an open environment, represented by a meadow, It showe d that at the end of hibernation, S. lineatus populations dispersed ma inly via air currents. The second device was located in a pea crop ent irely surrounded by a wooded area used as place of hibernation. The di stribution of S. lineatus caught in this protected environment reflect ed movements which were oriented towards directions not correlated wit h the wind direction. The third device was placed in a typical open en vironment of arable crops of the Paris Basin, and was used to determin e the movements between three main types of environment occupied by th e weevil: a hibernation zone (wooded area), a hibernation and/or feedi ng zone (clover) and a reproduction zone (pea). Crops on the ITCF expe rimental farm were colonised simultaneously at the beginning of spring , irrespective of environment, with two peaks in migration. (C) 1997 E lsevier Science B.V.