Résumé
Since Ehrlich & Raven (1964) introduced the concept of coevolution, phytophagous insects have been used to demonstrate mechanisms of coadaptation between plants and insects. G. Fraenkel (1959) had already stated that the "rai son d'etre of secondary plant substances" is an adaptation of plants to the attacks of insects. In most of the studies on this matter, attention is paid to the consumption of the plant tissues by insect larvae. Helationships between the adults of Bruchus affinis FrBlich (Col. Bruchidae) and Lathyrus spp. (Leguminosae) prove that the mechanisms involved can be much more complex.