Immunity
''Drosophila neotestacea'' and other mushroom-breeding Drosophila have been studied extensively for their interactions with '' Howardula'' nematode parasites, particularly '' Howardula aoronymphium''. Unlike related species, ''D. neotestacea'' is sterilized by ''H. aoronymphium'' infection. The genetic basis of this susceptibility is unknown, and is nematode-dependent. For instance, a related ''Howardula'' species from Japan does not sterilize ''D. neotestacea'', even though the European and North American ''Howardula'' species do. Moreover, the related '' Drosophila orientacea'' is resistant to infection by the European ''Howardula'' nematodes, but susceptible to the Japanese ''Howardula'' nematodes. Accordingly, nematode infection strongly suppresses genes involved in egg development. Comparisons between ''D. neotestacea'' and nematode-resistant members of the Testacea species group can help tease apart interactions of fly immunity genetics and nematode parasitism genetics. Initially discovered in ''D. neotestacea'', mushroom-feeding flies are commonly infected with the trypanosomatid parasite '' Jaenimonas drosophilae''. The major innate immunity pathways of ''Drosophila'' are found in ''D. neotestacea'', however the antimicrobial peptide Diptericin B has been lost. This loss of Diptericin B is also common to the related ''Drosophila testacea'' and ''Drosophila guttifera'', but not the also-related ''Drosophila innubila''. As such, these loss events appear to have been independent, suggesting that Diptericin B is actively selected against in these species; indeed, ''Diptericin B'' is conserved in all other Drosophila species. It also seems that unrelated Tephritid fruit flies have independently derived a ''Diptericin'' gene strikingly similar to the ''Drosophila'' ''Diptericin B'' gene. Like mushroom-feeding flies, these Tephritids also have a non- frugivorous sub-lineage that has similarly lost the Tephritid Diptericin B gene. These evolutionary patterns in mushroom-breeding ''Drosophila'' and other fruit flies suggests that the immune system's effectors (like antimicrobial peptides) are directly shaped by host ecology.Symbiosis
''Drosophila neotestacea'' can harbour bacterial symbionts including '' Wolbachia'' and notably '' Spiroplasma poulsonii''. The ''S. poulsonii'' strain of ''D. neotestacea'' has spread westward across North America due to the selective pressure imposed by the sterilizing nematode parasite '' Howardula aoronymphium''. While ''S. poulsonii'' can be found in other ''Drosophila'' species, the ''D. neotestacea'' strain is unique in defending its host against nematode infestation. Like other ''S. poulsonii'' strains, the ''D. neotestacea'' strain also protects its host from parasitic wasp infestation. The mechanism through which ''S. poulsonii'' protects flies from nematodes and parasitic wasps relies on the presence of toxins called ribosome-inactivating proteins (RIPs), similar to Sarcin or Ricin. These toxins cut a conserved structure in ribosomal RNA, ultimately changing the nucleotide sequence at a specific site. This leaves a signature of RIP attack in nematode and wasp RNA. ''Spiroplasma poulsonii'' likely avoids damaging its host fly by carrying parasite-specific complements of RIP toxins encoded on bacterial plasmids. This allows genes for RIP toxins to readily move between species bySelfish genetic elements
The Testacea species group is used inSee also
* Drosophila testacea species group * '' Spiroplasma'' * Meiotic driveReferences
{{Taxonbar, from=Q14591958 neotestacea Insects described in 1992