COMPARATIVE DEVELOPMENTAL BIOLOGY OF POPULATIONS OF 3 EUROPEAN AND ONE NORTH-AMERICAN EUBAZUS SPP (HYMENOPTERA, BRACONIDAE), PARASITOIDS OFPISSODES SPP WEEVILS (COLEOPTERA, CURCULIONIDAE)

Observations were made on the developmental responses of the North Ame rican braconid species, Eubazus crassigaster, a parasitoid of the whit e pine weevil, Pissoles strobi, and three European congeneric species, E. semirugosus, E. robustus, and Eubazus sp. Several populations of E ubazus spp. were compared in their phenology in the laboratory and und er natural conditions. When reared in the laboratory on non-diapausing Pissodes castaneus, mountain populations of E. semirugosus and E. rob ustus entered into an obligatory diapause in the host larva, whereas a ll the other populations tested developed continuously. Diapausing lar vae continued their development only after having experienced at least three months at 2 degrees C. Non-diapausing populations of Eubazus sp p. significantly differed in the duration of pre-imaginal development, with E. semirugosus being the fastest developing species and E. robus tus the slowest. Outdoor rearings of Eubazus spp. on P. castaneus show ed that E. crassigaster, Eubazus sp. and the lowland biotype of E. sem irugosus emerged in the year of oviposition if this occurred early eno ugh to allow parasitoid development. In contrast, a majority of E. rob ustus individuals overwintered in the host larvae, regardless of the o viposition date. The diapausing, mountain biotype of E. semirugosus is considered as the most promising candidate for control of P. strobi i n Canada, because it is likely to be better adapted to the life cycle of the target host than the other Eubazus spp., including the native E . crassigaster.