About the Project
Background: Conifer forests in central Europe are currently suffering from an enormous outbreak of bark beetles. Millions of hectares of spruce trees (Picea abies) in Germany and surrounding countries are being killed by the Eurasian spruce bark beetle (Ips typographus) due to warming temperatures that speed up the beetle life cycle and increase tree stress1. Successful attack of the spruce bark beetle is known to depend on the presence of free-living fungal symbionts, which the beetle inoculates into the attacked tree2. However, bacterial symbionts in the gut could also play an important role in promoting beetle attack by supplying critical nutrients or detoxifying host tree defenses3-5.
Project Description: We plan to investigate the role of the gut microbial community in promoting bark beetle development on spruce. First, we will survey the bacteria present in the digestive tract by sequencing 16S RNA amplicons from beetles raised on different diets and at different stages of development6. Next, we will manipulate gut microbes by antibiotic treatment and supplementation of cultured organisms to help test their function in providing nutrients and metabolizing host tree defenses, such as terpene resins and bark phenolics. Genomic and transcriptomic approaches will be employed to identify candidate genes in the most abundant bacterial taxa, and the encoded proteins characterized to determine their catalytic activity. Knowledge about the role of microbial gut symbionts in the bark beetle life cycle may give new insights into how insects are able to survive on trees with low nutrient content and abundant chemical defenses, as well as suggesting new strategies to combat this pest.
Candidate profile: We are looking for a highly motivated candidate with an MSc degree in microbiology, entomology, biochemistry, or a related field. Expertise in basic molecular biology is essential, and experience in biochemistry, analytical chemistry and bioinformatics is desirable.
Reading:
Biedermann PHW, Müller J, Grégoire J-C, Gruppe A, Hagge J, Hammerbacher A, Hofstetter RW, Kandasamy D et al. (2019) Bark beetle population dynamics in the Anthropocene: challenges and solutions. Trends Ecol. Evol. 34: 914-924.
Kandasamy D, Gershenzon J, Andersson MN, Hammerbacher A. (2019) Volatile organic compounds influence the interaction of the Eurasian spruce bark beetle (Ips typographus) with its fungal symbionts. ISME J. 13: 1788-1800.
Wadke N, Kandasamy D, Vogel H, Lah L, Wingfield BD, Paetz C, Wright LP, Gershenzon J, Hammerbacher A. (2016) Catechol dioxygenases catalyzing the first step in Norway spruce phenolic degradation are key virulence factors in the bark beetle-vectored fungus Endoconidiophora polonica. Plant Physiol. 171: 914-931.
Berasategui A, Salem H, Paetz C, Santoro M, Gershenzon J, Kaltenpoth M, Schmidt A. (2017). Gut microbiota of the pine weevil degrades conifer diterpenes and increases insect fitness. Mol. Ecol. 26: 4009-4110.
Douglas AJ. (2015) Multiorganismal insects: diversity and function of resident microorganisms. Annu. Rev. Entomol. 60:17-34.
Berasategui A, Axelsson K, Nordlander G, Schmidt A, Borg-Karlson A-K, Gershenzon J, Terenius O, Kaltenpoth M. (2016) The gut microbiota of the pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is similar across Europe and resembles that of other conifer-feeding beetles. Mol. Ecol. 25: 4014-4031
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