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Olfaction in Eurasian spruce bark beetle (lps typographus) larvae in response to symbiotic fungi

Lender, Laura (2023) BIOM02 20231
Degree Projects in Biology
Popular Abstract
Sniffing out friends and foes: Bark beetle larvae and fungal scents.

A tiny but destructive force is threatening Eurasian forest habitats – the Eurasian spruce bark beetle, Ips typographus. The larvae of this beetle species develop under the bark of conifers and feed on tree tissue. This leads to tree death and thus widespread devastation in wooded landscapes. The beetles live in partnership with microscopic fungi. The adult beetles locate their fungal partners via scent, but it is unknown whether larvae – the true culprits of tree death – can also recognise these fungi.

Unraveling the relationship between bark beetles and their fungal partners improves our understanding of this important insect pest. Fungi could be beneficial to... (More)
Sniffing out friends and foes: Bark beetle larvae and fungal scents.

A tiny but destructive force is threatening Eurasian forest habitats – the Eurasian spruce bark beetle, Ips typographus. The larvae of this beetle species develop under the bark of conifers and feed on tree tissue. This leads to tree death and thus widespread devastation in wooded landscapes. The beetles live in partnership with microscopic fungi. The adult beetles locate their fungal partners via scent, but it is unknown whether larvae – the true culprits of tree death – can also recognise these fungi.

Unraveling the relationship between bark beetles and their fungal partners improves our understanding of this important insect pest. Fungi could be beneficial to bark beetle larvae, for example by providing nutrients. But they can also be harmful and kill developing beetles. By elucidating larval responses to different fungi, we can gain a better understanding of the nature of the relation between the two partners.

In this study, I analysed the chemical scents emitted by six different fungal species. I recorded electrical signals in the sensory organs of bark beetle larvae to investigate whether they possess the necessary sensory equipment – so-called olfactory sensory neurons – to respond to the scent compounds produced by the fungal partners. In addition, I conducted simple behavioural tests in which the larvae had to choose between fungal scents and controls. This was to study whether larvae are attracted by fungal scents or avoid them.

I have found that scents emitted by different fungi are mostly distinct from each other. I have also shown that bark beetle larvae are equipped to perceive fungal odours. The larvae are not only able to react neuronally to fungal scents, but also show corresponding behaviour: They are attracted to the scent of a certain fungus, which also attracts adult individuals. The exact role of this fungus is not yet known, but the observed larval attraction suggests that the fungus plays an important role for this beetle species. In contrast, larvae clearly avoided a fungus that is expected to be harmful to them. The beetle larvae seem to be able to recognise the scent of this deleterious fungus as a source of harm, which causes avoidance behaviour.

Where do we go from here?

This study provides a first insight into the olfactory system of bark beetle larvae and thus lays the foundation for further research into olfaction of the Eurasian spruce bark beetle at this stage of development. By investigating the nature of fungal associations in this system and further exploring the sensitivities of the larval olfactory system, we can gain a deeper understanding of the biology of this species – a forest pest with far-reaching ecological and economic consequences.


Master’s Degree Project in Biology, 30 credits, 2023
Department of Biology, Lund University

Advisors: Martin N. Andersson and Dineshkumar Kandasamy
Pheromone group, Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Lender, Laura
supervisor
organization
course
BIOM02 20231
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
9136007
date added to LUP
2023-09-01 14:03:04
date last changed
2023-09-01 14:03:04
@misc{9136007,
  author       = {{Lender, Laura}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Olfaction in Eurasian spruce bark beetle (lps typographus) larvae in response to symbiotic fungi}},
  year         = {{2023}},
}