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Screening for infection by the endosymbiotic bacteria Wolbachia pipientis in Russian Melitaea butterflies

Bengzon, Isa (2019) BIOK01 20182
Degree Projects in Biology
Popular Abstract
Do Russian Melitaea butterflies contain the symbiotic bacteria Wolbachia?

Background
Up to 60 percent of insect species in the world are infected with the intracellular, obligate symbiont called Wolbachia pipientis, making it one of the most common arthropod endosymbionts, and potentially one of the most successful organisms on Earth. The bacterium affects its host species in negative and/or positive ways. In many insect species, infection causes disruption of the female to male ratio via a variation of female-favouring mechanisms. These include (I) male-killing, during which Wolbachia kills its male hosts at early or late developmental stages, (II) feminization; where males transform into fully functional females, and (III) cell... (More)
Do Russian Melitaea butterflies contain the symbiotic bacteria Wolbachia?

Background
Up to 60 percent of insect species in the world are infected with the intracellular, obligate symbiont called Wolbachia pipientis, making it one of the most common arthropod endosymbionts, and potentially one of the most successful organisms on Earth. The bacterium affects its host species in negative and/or positive ways. In many insect species, infection causes disruption of the female to male ratio via a variation of female-favouring mechanisms. These include (I) male-killing, during which Wolbachia kills its male hosts at early or late developmental stages, (II) feminization; where males transform into fully functional females, and (III) cell incompatibility between egg and sperm of individuals with a different infection status.

Project and hypothesis
In this project, I screen for infection by Wolbachia in a genus of fritillary butterflies known as Melitaea (first described by Fabricius, 1807). My hypothesis is that Wolbachia is present in Melitaea, and that infection is present in species across the Melitaea clade, since this is common in many arthropods.

Studies on Wolbachia are stellar opportunities to investigate host-symbiont relationships, which makes this project extra interesting as it focuses on infected butterflies from one specific country. The samples used in this study represented 17 species of Melitaea, and were all collected in Russia, making this study the first of its kind: a screening for Wolbachia presence in Russian Melitaea butterflies.

Method
By performing polymerase-chain-reactions (PCR) on DNA extracts from these butterflies, bacterial genes in the butterfly body can be amplified to large quantities. With a technique using specific gene markers called multi-locus-sequence-typing genes (MLST) Wolbachia infection can be detected after PCR amplification using agarose gel electrophoresis.

I collected the genetic sequences for the mitochondrial gene COI, which exists in all butterflies, to create a phylogenetic tree.

Result
The presence of Wolbachia was low, with amplification of the MLST genes appearing in only two species. Analysis of the phylogeny showed that these are separated by several speciation events.

This provides a good foundation for further studies on Wolbachia infection in Melitaea from other countries worldwide.

Thesis work for bachelor’s degree in Biology 15 hp 2019
Institution of Biology, Lund University

Supervisor: Anne Duplouy
Systematic biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Bengzon, Isa
supervisor
organization
course
BIOK01 20182
year
type
M2 - Bachelor Degree
subject
language
English
id
8972902
date added to LUP
2019-03-13 14:42:29
date last changed
2019-03-13 14:42:29
@misc{8972902,
  author       = {{Bengzon, Isa}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Screening for infection by the endosymbiotic bacteria Wolbachia pipientis in Russian Melitaea butterflies}},
  year         = {{2019}},
}