Entomotoxic activity of Rhinella icterica (Spix, 1824) toad skin secretion in Nauphoeta cinerea cockroaches: An octopamine-like modulation

Abstract Rhinella icterica is a poisonous toad whose toxic secretion has never been studied against entomotoxic potential. Sublethal doses of Rhinella icterica toxic secretion (RITS) were assayed in Nauphoeta cinerea cockroaches, in order to understand the physiological and behavioral parameters, over the insect central and peripheral nervous system. RITS (10 μg/g) injections, induced behavioral impairment as evidenced by a significant decrease (38 ± 14%) in the distance traveled ( p p n  = 28, respectively). In cockroaches semi-isolated heart preparations, RITS (16 μg/200 μl) induced a significant irreversible dose-dependent negative chronotropism, reaching ~40% decrease in heart rate in 20 min incubation. In in vivo cockroach neuromuscular preparations, RITS (20, 50 and 100 μg/g of animal weight) induced a time-dependent inhibition of twitch tension that was complete for 20 μg/g, in 120 min recordings. RITS (10 μg/g) also induced a significant increase in the insect leg grooming activity (128 ± 10%, n  = 29, p