Development of an insecticide prototype using the secretions on the parotoides glands of Rhinella schneideri toad

Abstract

Introduction: chemical substances able of eliminating and/or repelling insects are known as insecticides. When the need to use insecticides arose, highly toxic chemical compounds were used and these acted not only on insects but also on humans and the environment. From this, several studies were initiated with the objective of finding or synthesizing new compounds with selective action only for insects. Objectives: the objective of this study was, from studies of the toxicity of the secretions of the parotoid glands of the toad Rhinella schneideri, to elaborate an insecticide prototype. Methods: for this, the acute toxicity test and evaluation of the topical insecticidal activity in cockroaches of the genus Nauphoeta were performed. Results: in the acute toxicity test four solutions were tested, composed of different concentrations of secretions from the parotoid glands (10; 0.1; 0.01, and 0.001 mg/mL) of the toad Rhinella schneideri. The 10 mg/mL solution was the only one capable of killing all of the cockroaches. From this concentration, a second acute toxicity test was performed in which it was observed that at a concentration of 6 mg/mL, approximately half of the cockroach group died. The topical bioassay was carried out from the elaboration of an insecticide prototype composed of 10 mg/mL of the toad's parotoid gland poison in 20% of the organic solvent (acetone), used as a vehicle. In this bioassay, the death of all cockroaches was verified after 24h. Conclusion: it was possible to conclude that the insecticide prototype elaborated from the secretions of the parotoid glands of the toad Rhinella schneideri, using the organic solvent acetone 20% as the vehicle, was able to eliminate the cockroaches of the genus Nauphoeta, thus revealing the efficiency of the prototype developed.