Short version:

Some parasitic bacteria, such as Wolbachia, cause hosts from sexually-reproducing insect species to reproduce asexually instead, with an all-female line. Sometimes, all members of the species end up reproducing in this way - see e.g. Encarsia formosa wasps. How many generations can this remain viable before the effects of

  • reduced genetic diversity/inbreeding

  • possible reduced parasite resistance

  • etc.

take their toll?

If that's too vague a question, what is the longest time/no. of generations that induced-parthenogenetic species have been known to survive?

NOTE: This only applies to induced parthenogenesis resulting from e.g. parasitic bacteria infections. Not to naturally-occurring parthenogenesis.

Full version:

Certain parasitic bacteria, such as Wolbachia can induce thelytokous parthenogenesis in their haplodiploid insect hosts. The infection is passed on down the generations, from mother to daughters. Eventually, this can lead to speciation.

(In non-technical language... the effect of this is that infected female insects lay unfertilised eggs, which hatch exclusively into females, which later on lay unfertilised eggs which hatch into more female insects...

Members of a species which previously reproduced sexually now reproduce asexually, and the asexually-reproducing members of the species may eventually diverge so much from the others genetically that they become a separate species.)

All Hymenoptera (ants, wasps etc.) are haplodiploid.

One would expect that this would reduce genetic diversity in the infected population. A species which previously reproduced sexually, and now reproduces entirely asexually, might be expected long-term to lose biological fitness as a result of inbreeding depression. See also: "Muller's ratchet"

However, a 2001 paper investigated the effects of Wolbachia-induced parthenogenesis on Trichogramma wasp species, comparing such wasps to those that reproduced sexually and to those that were naturally parthenogenetic. Fewer of the infected wasp embryos survived to adulthood, but this was due to direct effects of the infestation on embryonic growth. Inbreeding depression was not a factor.

A 2000 paper also noted that Wolbachia can be horizontally transmitted through the sharing of a common food source, and stated:

horizontal transfer of parthenogenesis-inducing Wolbachia among offspring of infected females offers the potential for recombination between different Wolbachia variants and thus for circumventing Muller's ratchet.

Though I think that would only apply to the bacteria, not its host.

A notable example of Wolbachia-induced parthenogenesis is the chalcidoid wasp species Encarsia formosa. I don't know how long this has existed as a distinct species. Antibiotic treatment to kill the Wolbachia can restore their ability to give birth to males.

Is there a theoretical limit on the number of generations an induced-partheogenetic species should be able to survive? And what is the longest amount of time that any such species has been observed to survive?


Tagami, Y., Miura, K., & Stouthamer, R. (2001). How does infection with parthenogenesis-inducing Wolbachia reduce the fitness of Trichogramma?. Journal of Invertebrate Pathology, 78(4), 267-271. (Paywalled, unfortunately.)

Huigens, M. E., Luck, R. F., Klaassen, R. H. G., Maas, M. F. P. M., Timmermans, M. J. T. N., & Stouthamer, R. (2000). Infectious parthenogenesis. Nature, 405(6783), 178-179.

Stouthamer, R., & Luck, R. F. (1993). Influence of microbe‐associated parthenogenesis on the fecundity of Trichogramma deion and T. pretiosum. Entomologia Experimentalis et Applicata, 67(2), 183-192. (Paywalled.)

  • $\begingroup$ What a good question!I think that Wolbachia infections could be sustainable on the long term.Lots of species are currently infected by Wolbachia (looks like at least 25% of all insects species could host Wolbachia) and some scientists call it a symbiosis rather than an infection.In other words, I think Wolbachia doesn't lower the evolutionary success of its hosts. $\endgroup$ – zafalija Feb 1 '20 at 22:00
  • $\begingroup$ @Zafalija Bear in mind that Wolbachia infection affects different hosts in different ways. In some areas, there are species with 100% of the population infected, but no apparent symptoms. (Not even Wolbachia's famous biasing of sex ratios.) For example, in the Carpathian Basin, three of my favourite butterfly species - the Large Blue (Phengaris arion), Alcon Blue (Phengaris alcon) and Mountain Alcon Blue (Phengaris rebeli) are all 100% infected. And in the UK, 19 populations of another butterfly, Euphydryas aurinia, also have 100% Wolbachia prevalence, without any apparent effect! $\endgroup$ – Astrid_Redfern Feb 2 '20 at 12:42
  • $\begingroup$ Sources for the above: researchgate.net/publication/… and en.wikipedia.org/wiki/Euphydryas_aurinia $\endgroup$ – Astrid_Redfern Feb 2 '20 at 12:43
  • $\begingroup$ @Zafalija OK. I just wanted to get across that my question is explicitly about host species that it induces parthenogenesis in. It doesn't do that in any of the butterfly species with 100% infection that I mentioned. $\endgroup$ – Astrid_Redfern Feb 2 '20 at 13:19
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    $\begingroup$ And Wolbachia can be lost of course, e.g ncbi.nlm.nih.gov/pmc/articles/PMC6493766 Loss of cytoplasmic incompatibility in Wolbachia-infected Aedes aegypti under field conditions $\endgroup$ – Polypipe Wrangler Feb 2 '20 at 13:23

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