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Bark Beetle
© Matthias Herrmann/MPI for Developmental Biology, Tübingen

Entomo-Nematology

Project leader:
Matthias Herrmann

Department:
IV - Evolutionary Biology

Director:
Ralf. J. Sommer

Office:
Kostadinka Krause
Spemannstrasse 39
D-72076 Tübingen
Germany
Phone: +49 7071 601 484/441
Fax: +49 7071 601 498

Introduction

Nematodes are the most species-rich animal group on earth. They show a multitude of different lifestyles from being free-living in water or soil to being associated with other animals. And still, detailed knowledge on the biology and ecology of most nematode species is sparse to non-existent. We focus on the nematode family Diplogastridae, which are insect-associated nematodes. By having a closer look at the nematodes in their natural environment we want to get new insights into nematode distribution, speciation, phylogeny and their interaction with other animals. With this we are able to isolate an enormous number of nematodes new to science, which then can be brought in culture, characterized in detail and distributed to colleagues for all kinds of projects.

Publications

Projects

Bark beetles and their nematodes

Micoletzkya male (SEM picture by Jürgen Berger)
© Jürgen Berger/MPI for Developmental Biology, Tübingen Micoletzkya male (SEM picture)

Bark beetles (Coleoptera: Scolytidae) are without doubt a beetle group that affects forest ecology and human economy tremendously. To date there are about 6000 bark beetle species in 220 genera described, most of them very picky in the choice of the plants they infest. Some of them prefer deciduous trees, some coniferous trees and others even small herbs and shrubs.

With changing climate (i.e. less rainfall and higher temperatures) it is highly likely that the damage induced by bark beetles will increase dramatically.

We are interested in the nematode associates of bark beetles and other wood-boring insects.

Many of the nematodes we find are from the diplogastrid genus Micoletzkya (SEM picture of a male on the left) which is very tightly associated with bark beetles. The nematodes sit below the hind wings of the beetles in dauer larval stage (see video below) and will exit the beetles once these establish new galleries in the bark of til then uninfested trees.  In these galleries the nematodes fulfill their life-cycle, reproduce and eventually, when the offspring of the bark beetles are leaving the tree, a new generation of Micoletzkya dauer larvae will infest them and disperse to new trees.

 

Publications:

Wegensteiner, R., Wermelinger, B., Herrmann, M. (2015): Natural enemies of bark beetles: Predators, parasitoids, pathogens and nematodes. In: Bark beetles: Biology and ecology of native and invasive species (eds. Vega F.E., Hofstetter R.W.). Academic Press, London, pp. 247-304.

Susoy, V. & Herrmann, M. (2014): Preferential host switching and codivergence shaped radiation of bark beetle symbionts, nematode of Micoletzkya (Nematoda:Diplogastridae). Journal of Evolutionary Biology, 27, 889-898.

Susoy, V. & Herrmann, M. (2012) Validation of the genus Rhabditolaimus Fuchs, 1914 (Nematoda: Diplogastridae) supported by integrative taxonomic evidence. Nematology link

Susoy, V., Kanzaki, N. & Herrmann, M. (2012) Description of bark-beetle-associated nematodes Micoletzkya masseyi n. sp. and M. japonica n. sp. (Nematoda: Diplogastridae). Nematology, 15, 213-231.

Diplogastrid nematodes and their insects

latest phylogeny of diplogastrid nematodes
© Vladislav Susoy/MPI for Developmental Biology

Besides Micoletzkya we find many other diplogastrid nematodes together with insects. After isolation of nematodes from the insects we establish isogenic lines by transferring single gravid females to new plates. When these lines are established and growing we perform a more detailed characterization by sequencing several markers.

Sequencing results are used to construct molecular phylogenies that help us with the evolutionary interpretations of differences in developmental and ecological patterns. Molecular and morphological techniques are combined for state of the art species descriptions.

So far we have been able to discover four new diplogastrid genera in association with insects. All new taxa have been named and properly described.

Parapristionchus is the closest sister to the genus Pristionchus, Leptojaccobus is the most basal diplogastrid nematode. Sudhausia is the only viviparous genus in the family and Levipalatum the fifth hermaphroditic genus.

selected Publications:

Herrmann, M., Ragsdale, E. J., Kanzaki, N. & Sommer, R. J. (2013): Sudhausia aristotokia n.gen., m. sp. and S. crassa n. gen., n. sp. (Nematoda: Diplogastridae): viviparous new species with precocious gonad development. Nematology, in press, doi: 10.1163/15685411-00002738.

Ragsdale, E. J., Kanzaki, N. & Sommer, R. J. (2014): Levipalatum texanum n. gen., n. sp. (Nematoda: Diplogastridae) an androdioecious species from the south-eastern USA. Nematology, 16, 695-709.

Kanzaki, N., Ragsdale, E., Susoy, V., & Sommer, R. J. (2014): Leptojacobus dorci n. gen., n. sp. (Nematoda: Diplogastridae), an associate of Dorcus stag beetles (Coleoptera: Lucanidae). J. of Nematology, 46, 50-59.

Kanzaki, N., Ragsdale, E., Herrmann, M., Mayer, W.E., Tanaka, R. & Sommer, R.J.(2012) Parapristionchus giblindavisi n.gen, n.sp. (Rhabditida: Diplogastridae) isolated from stag beetles (Coleoptera: Lucanidae) in Japan. Nematology, 14 (8):933-947 [LINK]

Mayer, W.E., Herrmann, M. & Sommer,R.J. (2009) Molecular phylogeny of beetle associated diplogastrid nematodes suggests host switching rather than nematode-beetle coevolution. BMC Evolutionary Biology 2009, 9:212 doi:10.1186/1471-2148-9-212

Scientists involved:

Selected References:

Wegensteiner, R., Wermelinger, B., Herrmann, M. (2015): Natural enemies of bark beetles: Predators, parasitoids, pathogens and nematodes. In: Bark beetles: Biology and ecology of native and invasive species (eds. Vega F.E., Hofstetter R.W.). Academic Press, London, pp. 247-304.


Susoy, V. & Herrmann, M. (2014): Preferential host switching and codivergence shaped radiation of bark beetle symbionts, nematode of Micoletzkya (Nematoda:Diplogastridae). Journal of Evolutionary Biology, 27, 889-898.


Herrmann, M., Ragsdale, E. J., Kanzaki, N. & Sommer, R. J. (2013): Sudhausia aristotokia n.gen., m. sp. and S. crassa n. gen., n. sp. (Nematoda: Diplogastridae): viviparous new species with precocious gonad development. Nematology, 15, 1001-1020.

Kanzaki, N., Ragsdale, E. J., Herrmann, M., Roeseler, W. & Sommer, R. J. (2013): Pristionchus bucculentus n. sp. (Rhabditida: Diplogastridae) isolated from a shining mushroom beetle (Coleoptera: Scaphidiidae) in Hokkaido, Japan. J. of Nematology, 45, 77-84.


Susoy, V. & Herrmann, M. (2012) Validation of the genus Rhabditolaimus Fuchs, 1914 (Nematoda: Diplogastridae) supported by integrative taxonomic evidence. Nematology , 14, 595-604

Herrmann, M. & Sommer, R. J. (2011) The genome of Pristionchus pacificus and implications for survival attributes. In: Molecular and Physiological Basis of Nematode Survival (Eds. R. Perry & D. Wharton). pp. 86-98.


Herrmann, M., Kienle, S., Mayer, W.E., Rochat, J. & Sommer, R.J.(2010) Haplotype diversity of the nematode Pristionchus pacificus on Réunion in the Indian Ocean suggests multiple independent invasions. Biological journal of the Linnean Society ,100, 170-179.


Herrmann, M., Mayer, W.E, Hong, R.L., Kienle, S., Minasaki,R. & Sommer, R.J. (2007). The Nematode Pristionchus pacificus (Nematoda: Diplogastridae) is associated with the Oriental Beetle Exomala orientalis(Coleoptera: Scarabaeidae) in Japan. Zoological Science ,24: 883–889.


Herrmann, M., Mayer, W.E.& Sommer,R.J. (2006) Sex, bugs and Haldane's rule: the nematode genus Pristionchus in the United States. Frontiers in Zoology 3:14 doi:10.1186/1742-9994-3-14 [LINK]


Herrmann, M., Mayer, W.E.& Sommer,R.J. (2006) Nematodes of the genus Pristionchus are closely associated with scarab beetles and the Colorado potato beetle in Western Europe. Zoology , 109, 96–108

Non peer-reviewed articles
Herrmann, M. (2008) Eine Käferleiche zum Frühstück. GfBS Newsletter No.21
Herrmann, M., (2008) Worms on my scarabs. SCARABS. Occasional Issue Number 32; Print ISSN 1937-8343 Online ISSN 1937-8351