| Summary: | <i>Rhinella schneideri</i> is a common toad found in South America, whose paratoid toxic secretion has never been explored as an insecticide. In order to evaluate its insecticidal potential, <i>Nauphoeta cinerea</i> cockroaches were used as an experimental model in biochemical, physiological and behavioral procedures. Lethality assays with <i>Rhinella schneideri</i> paratoid secretion (RSPS) determined the LD<sub>50</sub> value after 24 h (58.07µg/g) and 48 h exposure (44.07 µg/g) (R<sup>2</sup> = 0.882 and 0.954, respectively). Acetylcholinesterase activity (AChE) after RSPS at its highest dose promoted an enzyme inhibition of 40%, a similar effect observed with neostigmine administration (<i>p <</i> 0.001, <i>n</i>= 5). Insect locomotion recordings revealed that RSPS decreased the distance traveled by up to 37% with a concomitant 85% increase in immobile episodes (<i>p <</i> 0.001, <i>n</i> = 36). RSPS added to in vivo cockroach semi-isolated heart preparation promoted an irreversible and dose dependent decrease in heart rate, showing a complete failure after 30 min recording (<i>p <</i> 0.001, <i>n</i> ≥ 6). In addition, RSPS into nerve-muscle preparations induced a dose-dependent neuromuscular blockade, reaching a total blockage at 70 min at the highest dose applied (<i>p <</i> 0.001, <i>n</i> ≥ 6). The effect of RSPS on spontaneous sensorial action potentials was characterized by an increase in the number of spikes 61% (<i>p <</i> 0.01). Meanwhile, there was 42% decrease in the mean area of those potentials (<i>p <</i> 0.05, <i>n</i> ≥ 6). The results obtained here highlight the potential insecticidal relevance of RSPS and its potential biotechnological application.
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