Tag Archives: hosts

Protection from Two Enemies with One Defense

Image Credit: Connor Long, CC BY-NC-SA 3.0, Image Cropped

Of poisons and parasites—the defensive role of tetrodotoxin against infections in newts (2018) Johnson et al., Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.12816

The Crux

Many organisms in nature produce powerful (and sometimes deadly) toxic substances, often taken as evidence that prey evolved chemical defenses against predators. Interestingly, these chemical defenses are deadly not only to predators, but also to parasites. This complementary defense, in addition to the ubiquity of parasites themselves, indicate that parasites may have had a hand in the evolution of host toxicity.

One particularly potent toxin found in the animal kingdom is tetrodotoxin (TTX). It can cause paralysis, difficulty with breathing, and even death in some cases. Newts in the genus Taricha are notorious for having high concentrations of TTX in their skin and eggs, and this has long been thought to have evolved as a defense against predators. In particular, Taricha newts and garter snakes (Thamnopholis spp.) are a classic example of arms-race dynamics (see Did You Know). Despite this relationship, newt toxicity and snake resistance to the toxin don’t always match up perfectly in nature, suggesting that other factors may influence newt toxicitiy. The goal of today’s study was to study parasitic infection and compare it to variation in toxicity among two newt species, the rough-skinned newt (T. granulosa) and the California newt (T. torosa).

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Taken For a Ride

This parasitic fungus takes over the brain and then ejects its spores out of the ant’s head (Image Credit: Erich G. Vallery, USDA Forest Service – SRS-4552, Bugwood.org, CC BY 3.0 US)

Mind Control: How Parasites Manipulate Cognitive Functions in Their Insect Hosts (2018) Libersat et al., Frontiers in Psychology, https://doi.org/10.3389/fpsyg.2018.00572

The Crux

The field of neuro-parasitology is a relatively new field in biology and deals with the study of parasites that manipulate the nervous system of their hosts for their own gain (usually at the expense of the host). The authors of this review focused on host-parasite interactions between insect hosts and their myriad of parasites, due not only to most studies in this field being done with insects, but also the fact that most animals on the planet are in fact insects.

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