EFFECT OF THE FOLIAGE OF DIFFERENT PINE SPECIES ON THE DEVELOPMENT AND OVIPOSITION OF THE PINE SAWFLY, DIPRION-PINI L (HYM, DIPRIONIDAE) .1. FOLIAGE EDIBILITY FOR D-PINI

To observe the effects of feeding on different hosts, young and old la rvae of the pine sawfly Diprion pini L. were fed with shoots of ten sp ecies or sub-species of pine: Pinus sylvestris, P. nigra nigricans var . austriaca, P. nigra laricio var. corsicana, P. nigra clusiana var. c ebennensis, P. pinaster, P. uncinata, P. radiata, P. contorta, P. bank siana and P. strobus. These tests were conducted under laboratory cond itions (16-degrees-C, 15H30/8H30 photoperiod for the young larvae, 20- degrees-C, 16H30/7H30 photoperiod for L4 and older larvae, 5000 lux). The foliage was renewed every 2-3 days. Large variations in the biolog ical characteristics of D. pini such as mortality, larval development rate, insect weight and fecundity, depending on the pine species, were proven. In all cases, the Scots pine appeared to be the best food. Fe eding with all the other species inparticular slowed down development. The worst results were obtained with the Austrian pine. The other bla ck pines and P. uncinata were more appropriate. The lack of damage on P. pinaster was explained by a very high mortality of the young larvae . Concerning the species of North American origin, D. pini presents a certain danger because of their utilization in afforestation in Europe . There is also the risk of the pine sawfly being introduced on the Am erican continent.