By Ricardo L. Palma, Curator of Terrestrial Invertebrates
Managing the survival and conservation of animal species which are in danger of extinction has become a widespread activity in many parts of the world. Until now, most of the conservation effort has been concentrated on birds and mammals, probably because they are relatively large, popular, warm blooded, and easily seen and identified in the wild. However, most people do not realise that living in association with birds and mammals, there are a vast number of other animal species, such as parasites, commensals, and other kind of host-specific affiliates, which would also become extinct together with the host (Dunn 2009).
The subject of conserving the parasites of endangered birds and mammals began to receive some attention in the 1990s with the publication of several short notes (see References).
“Equal rights for parasites!” was perhaps the most original slogan supporting the cause, as D.A. Windsor proclaimed in his note published in Nature magazine in 1990, and again in 1995. The most important message of those notes is that parasites are also part of Earth biodiversity and for that reason alone they deserve to be saved from extinction. However, there are several other good reasons to conserve parasites. Believe or not, some even argue that the presence of parasites – despite their reputation of damaging the host – may be beneficial. For example, flat-worms have been given to human patients suffering from a range of auto-immune diseases such as asthma, eczema, hay fever and food allergies with positive results. (See Helminthic therapy, Wikipedia, for more information.)
Considering all animal parasites, lice (wingless flat insects living upon the host during their entire life cycle) are among the most host-specific, meaning that usually one species of louse lives on only one species of host. There are some well-known examples of parasitic lice becoming extinct in historical times either because their only host is also extinct (for example, the New Zealand huia and its unique louse), or because the host population has been reduced to a critical point where no specimen harbours any louse anymore (the host-specific lice of the Californian condor, see Dunn 2009).
The case of the most endangered wild cat in the world, the Iberian lynx and its unique louse, is another example which, at present, is the subject of active research in Spain and Portugal. I was involved in the original description and naming of the Iberian lynx louse (as Felicola isidoroi) based on a single male found on one dead wild lynx in 1997 (Pérez & Palma 2001). This louse species has not been found again on the many other lynxes searched for lice since then. Consequently, the female of the Iberian lynx louse is still unknown and, judging from the estimated number of surviving lynxes and the lack of any other lice found, it is believed that this unique species may already be extinct (Anonymous 2014).
Another important issue resulting from the study and active search of the Iberian lynx louse is the dilemma which scientists face when dealing with lynxes captured alive to check their health status, or to breed in captivity in an attempt to boost the wild population by reintroducing more lynxes to their natural habitat (Pérez et al. 2013). Should all the parasites be removed from captured animals, supposedly to increase their chances of survival, as it was done with the Californian condor in the mid-1980s, or… should the host be left with all its parasitic fauna both to enhance its immune system and to preserve the entire biodiversity?
I certainly support and advocate for the second option!
Anonymous (12 June 2014). Científicos piden que se conserve el piojo del lince ibérico. Huelva Información, Medio Ambiente. Andalucía, Spain. http://andaluciainformacion.es/huelva/412790/cientificos-piden-que-se-conserve-el-piojo-del-lince-iberico/
Dunn, R.R. (2009). Coextinction: anecdotes, models, and speculation. Chapter 8. Pp. 167–180. In: Turvey, S.T. (Ed.) Holocene extinctions. Oxford University Press: New York. xii+ 352 pp.
Pérez, J.M. & Palma, R.L. (2001). A new species of Felicola (Phthiraptera: Trichodectidae) from the endangered Iberian lynx: Another reason to ensure its survival. Biodiversity and Conservation 10: 929–937.
Pérez, J.M.; Sánchez, I. & Palma, R.L. (2013). The dilemma of conserving parasites: the case of Felicola (Lorisicola) isidoroi (Phthiraptera: Trichodectidae) and its host, the endangered Iberian lynx (Lynx pardinus). Insect Conservation and Diversity 6: 680–686.
Rózsa, L. (1992). Points in question. Endangered parasites species. International Journal for Parasitology22(3): 265–266.
Stork, N. & Lyal, C.H.C. (1993). Extinction or ‘co-extinction’ rates? Nature 366: 307.
Windsor, D.A. (1990). Heavenly hosts. Nature 348: 104.
Windsor, D.A. (1995). Equal rights for parasites. Conservation Biology 9(1): 1–2.