FEEDING-ACTIVITY OF SITONA-LINEATUS L (COL, CURCULIONIDAE) ON PISUM-SATIVUM L (LEGUMINOSAE) DURING ITS IMAGINAL LIFE

At emergence, Sitona lineatus L., the pea leaf weevil, was extremely p olyphagous. It fed on various legumes without showing any specific pre ference for the pea. Sensitivity to the host plant became apparent in the reproductive period. The pea leaf weevil was then capable of disti nguishing between leguminous as well as different varieties of peas, a ccording to criteria that are still unknown. The fact that it fed on p eas did not lead to recognition. The triggering of feeding was tempera ture dependent. The threshold of 12 degrees C led to intense feeding t hroughout the population. Climatic factors were not solely responsible for feeding; there seemed to exist a rhythm specific to each individu al, probably related to the species' method of colonization. An indivi dual's consumption was measured in the laboratory by two methods. Firs t, by counting the characteristic notches made by the insect each time it fed, and second by measuring by image analysis the surface of the pea stipule consumed. The average daily consumption of an individual w as approximately 1.1 notches, representing a leaf area of about 5.8 mm (2). The quantity consumed was independent of the quantity of food pre sent and the phenological stage of the pea. The attack on the host pla nt was situated on the newer, more tender leaves. An individual's dail y food intake corresponded to 0.4 cal. The high concentration of prote in in the protein pea stipules (33.7% of the dry weight) would partly explain why populations in their reproductive period move from wild le gumes to cultivated legumes such as the pea.