The Insecticidal Activity of Rhinella schneideri (Werner, 1894) Paratoid Secretion in Nauphoeta cinerea Cocroaches

• Published in: Toxins Vol. 12; no. 10; p. 630
• Main Authors: Leal, Allan, Karnopp, Etiely, Barreto, Yuri Correia, Oliveira, Raquel Soares, Rosa, Maria Eduarda, Borges, Bruna Trindade, Goulart, Flávia Luana, Souza, Velci Queiróz de, Laikowski, Manuela Merlin, Moura, Sidnei, Vinadé, Lúcia, Rocha, João Batista Teixeira da, Dal Belo, Cháriston André
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.10.2020; MDPI
• Subjects: Acetylcholinesterase; AChE inhibition; Biocompatibility; Biotechnology; Cockroaches; Dosage; Enzymes; Heart; Heart rate; insect behavioral deficits; Insecticides; Insects; Lethality; Locomotion; Mass spectrometry; Muscles; natural insecticide; Nauphoeta cinerea; Neostigmine; neuromuscular blockade; Pesticides; Physiology; Rhinella schneideri; Scientific imaging; Secretion; toad parotid secretion; Toads; neuromuscular blockade; natural insecticide; insect behavioral deficits; AChE inhibition; toad parotid secretion
• ISSN: 2072-6651; 2072-6651
• DOI: 10.3390/toxins12100630

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, cockroaches were used as an experimental model in biochemical, physiological and behavioral procedures. Lethality assays with paratoid secretion (RSPS) determined the LD value after 24 h (58.07µg/g) and 48 h exposure (44.07 µg/g) (R = 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 ( 0.001, = 5). Insect locomotion recordings revealed that RSPS decreased the distance traveled by up to 37% with a concomitant 85% increase in immobile episodes ( 0.001, = 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 ( 0.001, ≥ 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 ( 0.001, ≥ 6). The effect of RSPS on spontaneous sensorial action potentials was characterized by an increase in the number of spikes 61% ( 0.01). Meanwhile, there was 42% decrease in the mean area of those potentials ( 0.05, ≥ 6). The results obtained here highlight the potential insecticidal relevance of RSPS and its potential biotechnological application.