Thursday, November 11, 2021



Parasites Benefit Their Hosts — At The Individual Level

Post #36

Donald A. Windsor                                                                                                      

Parasites are usually regarded as nasty symbionts that harm their hosts. The articles by Harris and Wickramasinghe and by Hu et al. show that some helminth parasites can actually benefit their hosts by inducing the production of antibacterial agents, in this case the SPRR2A protein. So, perhaps these helminths are not parasites but are some other form of symbiont.

Changing their designation is not merely a trivial argument over definitions. A fundamental puzzle I have been trying to solve is why parasites manage to survive. Why are hosts unable to evolve ways to render parasites extinct? An arms race is the usual answer, but I have a different one.

Parasitism is a property of life.

Life on Earth that is. A great deal of research is being done on trying to find extraterrestrial life. Will parasitism also be a property of that life?

References cited:

Harris, Nicola ; Wickramasinghe. A helminth-induced antimicrobial protein. Science 2021 November 5; 374(6568): 682-683.

Hu, Zehan ; Zhang Chenlu ; Sifuentes-Dominguez, Luis ; Zarek, Christina M. ; Propheter, Daniel C. ; Kuang, Zheng ; Wang, Yuhhao ; Pendse Mihir ; Ruhn, Kelly A. ; Hassell, Brian ; Behrendt, Cassie L. ; Zhang, Bo ; Raj, Pithvi ; Harris-Tryon, Tamia A.; Reese, Tiffany A. ; Hooper, Lora V.

Small proline-rich protein 2A is a gut bacterialcidal protein deployed during helminth infection. Science 2021 November 5; 374(6568): 710.

Windsor, Donald A. Parasitism as a property of life. Parasites Dominate 2013 September 3; Post #2.

Windsor, Donald A. Parasitism on Mars. Parasites Dominate 2015 November 8; Post #10.


Wednesday, April 14, 2021



Conservation of Parasites

Donald A. Windsor

Post #35

I recently published this open access item:

    Windsor, Donald A. Letter to the editor: Conservation of parasites. 

    International Journal for Parasitology: Parasites and Wildlife 2021 February 9; 14: 137.

Its main message is that parasites harm individual hosts but benefit their hosts by enabling them to survive as a species.

I offer the analogy that taxes harm individual members of society but benefit the society that enables them to survive.

After that, and more thought, I published this longer essay.

    Windsor, Donald A. Differences between conservation of parasites and of hosts.

    SciAesthetics Essays 2021 March 13: 1-4. DOI: 10.13140/RG.2.2.13254.80968

Its main message is that when a host is threatened or endangered, remove any parasites that may be contributing to its demise.


Wednesday, February 24, 2021



Index to Posts

Post # 34

Donald A. Windsor

The Parasites Dominate blog was launched in 2013 and has now published 34 posts. Here is the list.

Post #    Title                           Date

1 Introduction to this Blog. 2013 Aug 31

2 Parasitism as a Property of Life. 2013 Sep 3

3 Parasitism as a Form of Predation. 2013 Sep 6

4 Nine Hypotheses About Parasitism. 2013 Sep 9

5 Darwin's Entangled Bank is Maintained by Parasites. 2013 Sep 11

6 Parasite Cookies on Host Genomes. 2013 Sep 30

7 Parasites Benefit Their Hosts at the Species Level. 2014 Mar 16

8 My Epiphany Moment. 2015 Sep 12

9 Quantitating Role of Parasites in Ecosystem Using Energy Flow. 2015 Oct 19

10 Parasitism on Mars. 2015 Nov 8

11 Parasites Benefit Hosts with Survival Insurance. 2016 Oct 1

12 Parasite Benefits Host: Copepod on Shark Eyes. 2017 Mar 31

13 Role of Parasites in Earth's Biosphere. 2017Sep 30

14 Could a Paradigm about Parasites ever Shift the Traditional Paradigm of Ecology? 2017 Nov 2

15 Equal Rights for Parasites! 2017 Nov 5

16 27 Years of "Equal Rights for Parasites!" 2017 Dec 25

17 Probiotics and Parasites. 2018 Apr 25

18 Biobrokers in Parasite-Host Interactions. 2018 May 15

19 Intermediate Hosts and Biobrokers Deer Brainworm. 2018 May 28

20 Biobrokers as Catalysts and as Gatekeepers. 2018 Jun 6

21 Bioallies. 2018 Jun 9

22 Caenocholax fenyesi Males Hosted by Ants Females by Crickets. 2018 Jun 13

23 Gatekeepers in Arms Race. 2018 Jul 10

24 Parasites Caused the Phylogenetic Tree to Branch. 2018 Sep 9

25 Paradigm Shift Analyzed by the Shifter. Parasites Attain Equal Rights. 2018 Dec 6

26 Host Suicide Induced by Parasites Hemlock Wooley Adelgid. 2019 Feb 13

27 Deep Surface Biosphere Any Parasites? 2019 May 18

28 Hemiparasites Benefit Their Hosts at the Species Level. 2019 Jun 12

29 Did Humans Originate from Manipulation by Parasites? 2019 Jun 29

30 Are Parasites Singing Their Own Unceasing Song of Life? 2019 Jul 19

31 Conservation of Parasites: Emphasis as Species. 2020 Dec 26

32 How Many Habitats in Our Biosphere? 2021 Jan 18

33 Virocell Concept Applied to Parasites. 2021 Jan 30

34 Index to Posts. 2021 Feb 24 


Saturday, January 30, 2021



Virocell Concept Applied To Non-Viral Parasites

Post # 33

Donald A. Windsor

Viruses that harm their hosts are parasites. The popular notion that viruses are not alive has been dispelled by Patrick Forterre with his virocell concept (1, 2, 3). A virus is composed of a virion and a virocell. The virion is a protein capsule that contains a nucleic acid genome. The virocell is the host cell that accepts a virion and then produces more virions. The virus is the living organism. The virion is the equivalent of a plant seed.

If non-viral parasites (hereafter just called parasites) were regarded this way, the definitive host and its parasite, together, would be the living organism. The definitive host would be analogous to the virocell and the parasite would be analogous to the virion. The parasite would also be analogous to a seed.

Admittedly, this is an unconventional way of considering parasites.

But, it is consistent with my concept of considering parasitism as a property of life (4).

It is also consistent with my concept of the biocartel, first reported in 1997 (5).

A lot more thought has to go into this concept. For instance, some parasites have intermediate hosts in their life cycles. Do some viruses have intermediate virocells? Parasites may or may not reproduce in their intermediate hosts. Sometimes the intermediate host serves simply to transmit the parasite to its next host.

References cited:

1. Forterre, Patrick. Manipulation of cellular syntheses and the nature of viruses. The virocell concept. Comptes Rendus Chimie 2011; 14: 393-399.

2. Forterre, Patrick. The virocell concept and environmental microbiology. The ISME Journal [International Society for Microbial Ecology] 2013; 7:233-236.

3. Forterre, Patrick. Viruses in the 21st century: from the curiosity-driven discovery of giant viruses to new concepts and definition of life. Clinical Infectious Diseases 2017; 65 Supplement 1: S74-S78.

4. Windsor, Donald A. Parasitism as a property of life. Parasites Dominate 2013 September 3; Post #2.

5. Windsor, Donald A. The basic unit of evolution is the host-symbiont "biocartel". Evolutionary Theory 1997 August; 11(4): 275.


Monday, January 18, 2021



Post # 32

How Many Habitats In Our Biosphere?

Donald A. Windsor

Many more than realized some multiple of the total number of free-living species. Because every free-living species hosts one or more species of parasite. To a parasite, its host is its habitat. Parasites with complex life cycles dwell in several habitats. Moreover, some parasites host their own parasites.

A host provides several habitats. Each organ or tissue could be a habitat for parasites. Parasites that enter the gastrointestinal tract and travel to a specific tissue have to pass through other tissues to get to their final destination. So, the total number of habitats is a multiple of the total number of hosts.

Some free-living species host large numbers of parasite species. The American Robin (Turdus migratorious) is the host for at least 94 parasite species (1). The European Starling (Sturnus vulgaris), a cosmopolitan bird, is host to at least 175 parasite species (2). These are just the species I could document in the literature. There are likely to be many more yet to be discovered.

In addition to all the biological habitats are the non-biological habitats.

The upshot is that while the exact number of habitats on Earth may be too elusive to calculate, it is safe to proclaim that the number is astronomical.

References cited:

1. Windsor, Donald A. Biocartel of the American Robin (Turdus migratorious). Archives of the SciAesthetics Institute 2000 August; 1(1): 13-18.

2. Windsor, Donald A. Biocartel of the European Starling (Sturnus vulgaris). Archives of the SciAesthetics Institute 2000 August; 1(1): 19-28.


Saturday, December 26, 2020


 Post #31

Conservation of Parasites: Emphasis as Species

Donald A. Windsor

Successful conservation of parasites is being handicapped because people (including many scientists) are not always differentiating between parasites as individuals and parasites as species.

Here is what must be emphasized. Species evolve. Individuals do not.

Parasites, as individuals, harm their hosts, by definition.

Parasites, as species, actually benefit their host species.

At the species level, parasites benefit their hosts by enabling them to survive. Parasites manage the ecosystems in which the hosts live. Without suitable ecosystems, the hosts would have to either go extinct or evolve into new species.

Without parasites, ecosystems would deteriorate into just a few monocultures of very aggressively invasive species. Biodiversity is due to parasites. 



Friday, July 19, 2019


Are Parasites Singing Their Own Unceasing Song Of Life?
Post #30
Donald A. Windsor

Well, parasites may not be singing, but they sure are showing off their most visible presence – biodiversity.

James Lovelock referred to the infrared signal of the oxygen-methane disequilibrium radiating from Earth's atmosphere as an "unceasing song of life".

"This unceasing song of life is audible to anyone with a receiver, even from outside the Solar System." (1).

If Lovelock's statement is correct, then this song would indicate life on any extraterrestrial entity.

After such life is found, perhaps it could reveal whether parasitism is, or is not, a universal property of life. I suspect that it is.

Here on Earth, our life exhibits parasitism. But, what would life look like without parasitism? I suspect that the signature hallmark of life is biodiversity. But biodiversity can result from life adapting to environmental forces, such as competition, predation, habitat, and climate.

Parasites enhance biodiversity by thwarting monocultures. Therefore, the absence of monocultures on extraterrestrial entities could be a signature of parasitism.

However, how would a monoculture be recognized? On Earth we have no naturally occurring pure monocultures; they exists only in labs or buildings. Our so-called monocultures, such as with agricultural crops like corn and wheat, always have other species living among them.

Here is a handy metric that I propose. In a monoculture, the number of individuals of one species is at least 1 magnitude higher than the total number of individuals of all the other species combined, in the same area.

For example, if a bean field had 10,000 individual bean plants, then it would be a monoculture if the total number of individuals of all the other species in that field was under 1,000, a difference of 1 order of magnitude.

This metric would not be able to compare macro-species with microbial species, because the microbes would always outnumber the macros. However, it may be useful in comparing a monoculture of a microbe with other microbial species.

So, while the unceasing song of parasitism may not be a song, it may be an image visible to anyone with a viewer.

Reference cited:

1. Lovelock, James. The Ages of Gaia. A Biography of Our Living Earth. 2nd Edition. New York, NY: Oxford University Press. 2000. 268 pages. Quote on page 7 of the Introductory.