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Mechanisms behind hornworm self-defense discussed at the 2023 American Physiology Summit

Image of M Sexta By Th1rt3en via Wikimedia Commons

Graduate student Christian Valtierra presented research conducted in Dr. Megumi Fuse’s lab (San Francisco State University) at the 2023 American Physiology Summit last month. The research was focused on examining the defensive strike response in Manduca sexta hornworms.

Animals respond to potentially damaging stimuli with the help of sensory neurons, called nociceptors, that specialize in detecting these stimuli. In humans, activation of these receptors is what causes us to perceive pain. Receptor activation causes animals to change their behaviors to avoid the stimulus. When the receptors are activated over a long period of time, it can result in nociceptive sensitization, which is characterized by changes in the nervous system as well as heightened sensitivity to the stimulus. It is this sensitization that can also contribute to chronic pain.

Research in Dr. Fuse’s lab has shown that when M. sexta hornworms are touched, they respond with a very fast “defensive striking” behavior after which they become more sensitive to stimuli. In fact, they found that the hornworms have an increased sensitivity to lighter touches for close to 24 hours after the initial poke. Christian’s research aims to figure out how neurons in these hornworms become sensitized.

You can read more about Dr. Fuse’s research on her website.


Christian Valtierra, Dennis Tabuena, and Megumi Fuse. Pain and Plasticity: Spike Sorting Based Approach for Characterizing the Neural Circuitry Mediating Nociceptive Sensitization of the Defensive Strike Response in M. sexta. Presented at the 2023 American Physiology Summit in Long Beach, CA.

Categories: Agriculture, Aquaculture, and Livestock, Intelligence and Neuroscience, Physiology on the Road, Stress

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