Are Climates in Canada and the United States Suitable for the European Spruce Bark Beetle, Ips typographus, and Its Fungal Associate, Endoconidiophora polonica?

Invasions of exotic forest insects and pathogens can devastate evolutionarily naïve habitats and could cause irreversible changes to urban and natural ecosystems. Given the ever-increasing volume of trade in wood and plant stock worldwide, establishment of non-native pests under climate change is one of the most important forest health concerns currently. The European spruce bark beetle, Ips typographus, is a damaging, phloem-feeding insect of Norway spruce, Picea abies, in Eurasia. Endoconidiophora polonica is the most virulent ophiostomatoid fungal associate of I. typographus. Spruce species native to North America are susceptible to this insect-pathogen complex. We studied the suitability of ‘current’ (1970–2000) and future climates (2021–2100) in Canada and the United States for these two species via ensemble species distribution models. We also determined overlapping regions favorable to both I. typographus and E. polonica. Our results indicate that, currently, climate is particularly suitable for I. typographus and E. polonica in western Canada and throughout the United States. Northward shifts in climatic suitability are projected to occur in Canada for both species under climate change. By the end of the 21st century, a coast-to-coast corridor of climatic suitability for I. typographus and E. polonica will occur in Canada under high-temperature regimes.

Phylogeny of Leptographium Qinlingensis Cytochrome P450 Genes and Their Expression When Grown on Different Media or Treated With Terpenoids

Leptographium qinlingensis is a fungal associate of the Chinese white pine beetle (Dendroctonus armandi) and a pathogen of the Chinese white pine (Pinus armandi) that must overcome the terpenoid oleoresin defences of host trees. We identified and phylogenetically analysed the cytochrome P450 (CYP) genes in the transcriptome of L. qinlingensis. Through analyses of the growth rates on different nutritional media and inhibition by terpenoids, the expression profiles of six CYPs in the mycelium of L. qinlingensis grown on different media or treated with terpenoids were determined. The CYP evolution predicted that most of the CYPs occurred in a putative common ancestor shared between L. qinlingensis and G. clavigera. This fungus is symbiotic with D. armandi and has more similarity with G. clavigera, which can retrieve nutrition from pine wood and utilize monoterpenes as the sole carbon source. Some CYP genes might be involved in the metabolism of fatty acids and detoxification of terpenes and phenolics, as observed in other blue-stained fungi, which also indicates the pathogenic properties of L. qinlingensis in Chinese white pine.