Inibidor de tripsina de Enterolobium contortisiliquum interfere no desenvolvimento das larvas de Aedes aegypti e potencializa a ação das proteínas cry oriundas do Bacillus thuringiensis

Abstract

Urban insects are barriers to human development such as agricultural pests and vectors of disease. The use of synthetic chemicals to control these insects has caused damage to the environment and contributed to the emergence of resistant insects. Thus, in recent years, the search for new molecules of plant origin with insecticidal activity, such as protease inhibitors and, in parallel, its synergistic effects with substances that have this recognized effect has increased. Thus, the objective of this work is to evaluate the insecticidal activity of a protease inhibitor of Enterolobium contortisiliquum (Vell.) Morong seeds. (EcTI) and its potentiating action of insecticidal activity on Aedes aegypti larvae of Bacillus thuringiensis protoxins. After the purification steps, SDS-PAGE showed a band of apparent molecular weight of 20 kDa. The EcTI showed in vitro inhibitory activity on trypsin and on larval intestinal proteases and bacteria. EcTI showed no acute toxicity to mosquito larvae, even at maximum concentration (1,000 μg.mL-1), but presented a delay in larval development when submitted to chronic exposure (710 μg.mL-1). The zymogram showed that the larvae incubated at small concentrations of EcTI (50 to 400 μg.mL-1) promoted increased activity of the intestinal proteases, and these enzymes decreased the lethal concentrations (LC50 and CL20) of the protoxins, with the increase of their activation. However, this toxicity was not observed in Artemia nauplii when tested at the maximum concentrations used with larvae. The results suggest that EcTI is promising for the development of new insecticides to control this important vector.