Publication Alert: How might semantic value associations have impacted the study of parasites?
Antarctophthirus trichechi louse; photo credit to Vince Smith (Wikipedia Commons)
‘Biologically Degenerate, Ecologically Marginal’: Parasites as a Case Study in Societal Values Impacting Ecological Research (Barrett et al. 2025; Philosophy, Theory, and Practice in Biology)
During my dissertation, I briefly worked on some solitary, predatory wasps in New York State. The wasps, Isodontia auripes, paralyze katydids with their venom and bring them back live to the nest, where hungry larvae wait to consume the living prey before pupating to overwinter. As I pried apart the wooden boards of my artificial nests on my kitchen table that fall so that I could document the number of pupae, I was shocked to discover a cloud of tiny, parasitic wasps emerging. Several hundred parasitic wasps, wings glittering like dust in sunlight, flooded the downstairs of my house. (My husband did not find this story amusing.)
As I looked down at that empty nest, I saw the brown pupal case that contained the larvae all those wasps had eaten lying amongst all the discarded bits of the katydids that this same wasp had itself eaten, and I briefly wondered: “What’s the difference, here, between a parasite and a predator? Aren’t they both just… eating?”
This question made me feel, as a graduate student with a decent background in ecology, kind of stupid. But, it turns out it wasn’t as stupid as I thought; after all, E.O. Wilson said it best: “Parasites, in a phrase, are predators that eat prey in units of less than one“. And there’s much more subtle variation in how we classify these consumer organisms ecologically than I had originally learned about in my undergraduate ecology curricula. But what mattered to me when I read this quote by Wilson was the sensation that I had sort of… felt like there was some very meaningful difference between parasites and predators that was actually not there. I returned to my undergraduate textbook and read over the sections on parasites and predators and the kinds of roles they play in ecosystems; how they are (or aren’t) incorporated in food webs; and, in conservation, which animals were especially important success stories and worthy of preservation.
What I found in that educational resource helped me develop a theory for my own sense, as a young ecologist, of the value of parasites and predators. First, I noticed that parasites were frequently missing - they received much less coverage in the book compared to predators (see Figure 1).
Figure 1: Parasites are neglected in ecological textbooks compared to predators. Twelve online ecology textbooks published in the last 15 years were searched for parasit* or predat* containing words using the ProQuest, RedShelf, or Amazon kindle search tool. The number of parasit* containing words was divided by the number of predat* containing words; a ratio of less than one means that parasites are not equivalently represented.
I noticed that they were missing from food webs; missing from stories of conservation success; and rarely documented as having critical ecosystem functions worth preserving. In fact, even where they were present, they didn’t get much credit: predators were talked about as ‘taking out sick prey’ and thereby regulating disease and prey populations… ignoring the fact that parasites might be the original agent of change, by making the prey sick to begin with. I wondered why it was that these two organisms - both fundamentally classes of consumers - were given such divergent treatment in my educational materials. And thus, sparked this paper with Bob Fischer and Tom Raffel.
In our paper, we document the history of the words parasite and predator - both of which were used to describe humans in a social context long before they were adopted by ecological theories. We talk about the values associated with those terms - and how those values might have shaped ecological theories when they were adopted. We demonstrate bias against parasites in much of the foundation ecological literature - much of which is now having to be corrected, given the increasingly important roles we now know parasites play. We contend that semantic value associations, alongside many other factors - like morphological similarity, difficulty of observation, etc. - may have played some role in the divergence in how ecologists theorize about parasites and predators.
In the end, we present some proactive ways scientists could move forward, trying to proactively identify and head off these kinds of semantic problems in the future (where we think they may be detrimental to, instead of improving, our science). We also talk about what to do when a value is already embedded in a discipline, such as is the case with parasites (or even the ‘Queen’ bee). A huge thanks to my interdisciplinary collaborators for agreeing to take on this wild and crazy project with me!
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