Abstract:
Ips typographus (Coleoptera, Scolytinae) is a spruce-infesting bark beetle that occurs throughout
Europe and Asia. The beetle can cause considerable damage, especially when colonized trees are stressed and
beetle populations increase. Although some studies have shown that populations of I. typographus in Europe,
China and Japan are genetically distinct, these populations are biologically similar, including a strong association
with ophiostomatoid fungi. To date, only two Leptographium spp. have been reported from the beetle in China,
while 40 species have been reported from Europe and 13 from Japan. The aims of this study were to identify the
ophiostomatoid fungal associates of I. typographus in north-eastern China, and to determine whether the fungal
assemblages reflect the different geographical populations of the beetle. Field surveys in Jilin and Heilongjiang
provinces yielded a total of 1046 fungal isolates from 145 beetles and 178 galleries. Isolates were grouped based
on morphology and representatives of each group were identified using DNA sequences of the ribosomal LSU, ITS,
β-tubulin, calmodulin and elongation factor 1-α gene regions. A total of 23 species of ophiostomatoid fungi were
identified, including 12 previously described species and 11 novel species, all of which are described here. The
dominant species were Ophiostoma bicolor, Leptographium taigense and Grosmannia piceiperda D, representing
40.5 %, 27.8 % and 17.8 % of the isolates, respectively. Comparisons of species from China, Europe and Japan
are complicated by the fact that some of the European and all the Japanese species were identified based only on
morphology. However, assuming that those identifications are correct, five species were shared between Europe,
Japan and China, two species were shared between China and Japan, five between Europe and China, and two
between Europe and Japan. Consequently, Ips typographus populations in these different geographic areas have
different fungal assemblages, suggesting that the majority of these beetle-associations are promiscuous. The
results also suggested that the symbionts of the bark beetle do not reflect the population structures of the beetle.
The use of fungal symbiont assemblages to infer population structures and invasion history of its vectors should
thus be interpreted with circumspection.
