The development of the solitary endoparasitic braconid Glyptapanteles porthetriae in gypsy moth larvae of different ages was studied. Host larvae were parasitized during the premolt to the 2nd instar (A-larvae), to the 3rd instar (B-larvae) or to the 4th instar (C-larvae), respectively. The percentage of successfully parasitized larvae decreased markedly with the age of the host at the time of parasitization. When parasitization occurred at the premolt to the second or third instar, parasitoid larvae successfully emerged at rates of 68% and 57%, respectively, in contrast to the 17% from larvae parasitized in the premolt to the fourth instar. In all three groups of parasitized larvae the final host instar was significantly longer than the corresponding instar of unparasitized control larvae of the same age. However, the growth and growth rate of parasitized larvae were reduced compared to control larvae. Due to the extremely low rate of successful development of G. porthetriae in C-larvae, parameters of parasitoid development were only recorded in A and B-host larvae. In both the parasitoid growth was slow during the first instar but rapidly increased during the second instar. Total developmental time of the parasitoid was significantly longer in B-host larvae, and the resultant cocoons were heavier than those that developed in A-host larvae, but proportionally fewer of the offspring were females. Within both groups the female wasps took significantly longer to develop than the males.
The eight spined larch bark beetles infest various species of Larix in Europe and Asia. Ips cembrae is the only Ips species with larch as its main host. Ips subelongatus, Ips fallax, Ips shinanonensis and Ips cembrae var. engadinensis are treated as synonyms of I. cembrae. These three putative species and the one variety are distinguished by their host tree and geographic distribution, as it is not possible to distinguish them on the basis of morphological differences. Beetles were collected from European and Asian populations, and from hosts and geographic areas where the species were first found and described and in their natural ranges of distribution. These beetles were used to study the phylogenetic relationships of the eight spined larch bark beetles. A region of the mitochondrial gene was analysed and the blue-stain fungi associated with I. cembrae in Europe were investigated and compared with those recorded as associated with the larch bark beetle in Japan. Only minor sequence differences were detected between the populations in Europe and Asia. However, the European populations differed by 4.3% from the Asian populations. The phylogenetic analysis placed the European and Asian haplotypes in significantly distinct clusters. This distinction was supported by the finding of an insertion/deletion in a non-coding region of the mitochondrial DNA. Furthermore, there are differences in the fungi associated with the eight spined larch bark beetles in Europe and Japan. The results suggest that the I. cembrae complex contains at least two taxa: I. cembrae infesting larch in Europe and I. subelongatus infesting larch in Asia.