Longicorn beetle that vectors pinewood nematode carries many Wolbachia genes on an autosome
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Updated: Jun 20, 2026
Observation and Quantification of Mating Behavior in the Pinewood Nematode, Bursaphelenchus xylophilus
Published on: December 25, 2016
Takuya Aikawa1, Hisashi Anbutsu, Naruo Nikoh
1Tohoku Research Center, Forestry and Forest Product Research Institute, Morioka, Japan. taikawa@ffpri.affrc.go.jp
Abstract:
Monochamus alternatus is the longicorn beetle notorious as a vector of the pinewood nematode that causes the pine wilt disease. When two populations of M. alternatus were subjected to diagnostic polymerase chain reaction (PCR) detection of four Wolbachia genes, only the ftsZ gene was detected from one of the populations. The Wolbachia ftsZ gene persisted even after larvae were fed with a tetracycline-containing diet for six weeks. The inheritance of the ftsZ gene was not maternal but biparental, exhibiting a typical Mendelian pattern. The ftsZ gene titres in homozygotic ftsZ(+) insects were nearly twice as high as those in heterozygotic ftsZ(+) insects. Exhaustive PCR surveys revealed that 31 and 30 of 214 Wolbachia genes examined were detected from the two insect populations, respectively. Many of these Wolbachia genes contained stop codon(s) and/or frame shift(s). Fluorescent in situ hybridization confirmed the location of the Wolbachia genes on an autosome. On the basis of these results, we conclude that a large Wolbachia genomic region has been transferred to and located on an autosome of M. alternatus. The discovery of massive gene transfer from Wolbachia to M. alternatus would provide further insights into the evolution and fate of laterally transferred endosymbiont genes in multicellular host organisms.
Insights
A large genomic region from Wolbachia bacteria was transferred to the Monochamus alternatus beetle genome. This massive gene transfer was found on an autosome, offering insights into endosymbiont gene evolution in hosts.
Area of Science:
- Genomics
- Insect Biology
- Microbial Genetics
Background:
- Monochamus alternatus beetles transmit the pine wilt disease pathogen.
- Wolbachia are intracellular bacteria known to infect insects.
- Understanding endosymbiont gene transfer is crucial for evolutionary biology.
Purpose of the Study:
- To investigate the presence and integration of Wolbachia genes in M. alternatus.
- To determine the inheritance pattern and location of detected Wolbachia genes.
- To explore the implications of massive gene transfer from endosymbionts to insect hosts.
Main Methods:
- Polymerase chain reaction (PCR) for Wolbachia gene detection.
- Tetracycline treatment to assess gene persistence.
- Fluorescent in situ hybridization (FISH) for gene localization.
- Mendelian inheritance analysis.
Main Results:
- The Wolbachia ftsZ gene was detected and persisted despite antibiotic treatment.
- Biparental inheritance of the ftsZ gene was observed, following Mendelian patterns.
- A large number of Wolbachia genes were detected in both insect populations, with many containing mutations.
- FISH confirmed the integration of Wolbachia genes onto an M. alternatus autosome.
Conclusions:
- A significant portion of the Wolbachia genome has been transferred to the M. alternatus nuclear genome.
- These transferred genes are located on an autosome and exhibit Mendelian inheritance.
- This discovery provides a unique model for studying the long-term fate and evolutionary impact of endosymbiont gene transfer in eukaryotes.
