Stained Wolbachia pipensis inside wasp egg.
Wolbachia is a very common and very interesting group of bacteria. It infects insects and arthropods, living inside their cells, and is known for modifying the reproduction of host species in a variety of ways. It may play a role in rapid speciation, lateral gene transfer, and has potential as a vector in genetic engineering.
Some of the ways Wolbachia modifies reproduction:
Wolbachia can also cause bidirectional incompatibility. This may lead to rapid speciation. For example, Nasonia is a wasp genus consisting of three sibling species. They can’t reproduce with each other, and each species has its own strain of Wolbachia. It is, however, unclear which one preceded the other.
Vertical gene transfer is the usual, parent to offspring. Gene transfer outside parent-to-offspring is called lateral gene transfer. It’s uncommon to see lateral gene transfer between prokaryotes and multicellular eukaryotes, but scientists have found evidence of gene transfer between Wolbachia and insect as well as roundworm species. Some species had the entire Wolbachia genome embedded in their own.
Finally, there’s the potential for using these bacteria in biological control. Genetic engineers prefer to piggyback on nature: that way is a lot easier. Genetically modified Wolbachia can potentially be used to control insects that carry diseases like Malaria, either by transferring genes that make the carriers unable to carry the parasite, or by using Wolbachia's manipulation of reproduction to reduce the fertility of the insect population.