Seminario dottorato di ricerca

Wednesday November 25, 2015 at 4:00 p.m.
Aula Giacomini
Dipartimento di Biologia Ambientale

Dottorato in Biologia Ambientale ed Evoluzionistica

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"How Praying Mantises Recognize Prey: Merging Ecology, Psychology, and Neurobiology"

Frederick R. Prete, Ph.D. Department of Biology, Northeastern Illinois University - Chicago, IL, USA

The praying mantises are a group of charismatic predatory insects with a rich literary history. Despite this, much of the pertinent mid-20th century scientific literature was based on erroneous assumptions about these animals. In particular, mantises were thought to be reflex-bound, and neurologically, morphologically, and behaviorally designed to capture only small, “fly-sized” prey. In the field, however, mantises are adept at capturing a wide range of prey items including same-sized conspecifics and the occasional vertebrate. Psychophysical studies done in our lab have demonstrated that mantises do not recognize these various prey items explicitly (e.g., by matching-to-template). Instead, they do so implicitly by simultaneously assessing several stimulus parameters (e.g., size, orientation, movement, and contrast). If a sufficient number of parameters meet threshold levels, the object is seen as prey. This is analogous to how humans, for instance, identify an exemplar of an abstract category such as “attractive person”. We are now exploring the neural networks underpinning prey recognition. Electroretinograms (ERGs) recorded from the compound eyes of several mantis species indicate that luminance increments elicit robust photoreceptor depolarizations similar to those created by TRPL (transient receptor potential-like) cation channels. These depolarizations are opposed by rectifying currents similar to the voltage gated potassium currents seen in other insects. Luminance decrements (e.g., as would be caused by moving prey), elicit both photoreceptor hyperpolarizations, and depolarizations of lamina monopolar cells (LMCs) on which photoreceptors synapse. We believe that a subset of LMCs synapse on lobula giant movement detector interneurons (LGMDs), the activity of which we have shown to be correlated both with the appearance of prey-like stimuli and with the occurrence of predatory strikes in intact mantises.

 

 

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