ABSTRACT
BACKGROUND: A dichloromethane-methanol extract of the seeds of Piper tuberculatum Jacq. (Piperaceae) and two isobutyl amides, 4,5-dihydropiperlonguminine (1) and pellitorine (2), which were isolated by chromatographic methods, were assayed for their lethality against the sugarcane borer Diatraea saccharalis F. (Lepidoptera: Pyralidae). RESULTS: Bioassays were carried out with fourth-instar caterpillars through topical application of test solutions to the dorsal surface of the prothorax, and dose-response correlations were determined. Significant insect mortalities were observed 24, 48 and 72 h after treatment at concentrations of >or= 100 microg insect(-1). The LD(50) and LD(90) values for compound 1 were 92.83 and 176.50 microg insect(-1), and for compound 2 they were 91.19 and 184.56 microg insect(-1). CONCLUSION: According to the LD(50) and LD(90) for compounds 1 and 2, it can be inferred that the values reflect an acute lethal response to both compounds, based on interaction(s) of the toxicants with a primary target or series of targets. Thus, the amides were demonstrated to have potential value in the control of the sugarcane borer.
Subject(s)
Amides/pharmacology , Benzodioxoles/pharmacology , Fatty Acids, Unsaturated/pharmacology , Insecticides/pharmacology , Moths/drug effects , Polyunsaturated Alkamides/pharmacology , Amides/chemistry , Animals , Benzodioxoles/chemistry , Dose-Response Relationship, Drug , Fatty Acids, Unsaturated/chemistry , Insecticides/chemistry , Larva/drug effects , Lethal Dose 50 , Molecular Structure , Plant Extracts/chemistry , Plant Extracts/pharmacology , Polyunsaturated Alkamides/chemistry , Seeds/chemistry , Time FactorsABSTRACT
Acetone and ethanol extracts of the tubercula and several compounds isolated from Aristolochia pubescens (Willd) were bioassayed on velvetbean caterpillars, Anticarsia gemmatalis (Hübner), for evaluation of the insecticidal activities. Of the extracts subjected to bioassay, the acetone extract showed the highest activity. (-)-Cubebin did not show activity against soybean caterpillars, whereas aristolochic acid and ent-kaur-15-en-17-ol increased the larval period. These compounds, and (+)-eudesmin and (+)-sesamin, reduced the viability of this period, giving rise to malformed adults. These extracts and compounds are therefore potential botanical insecticide agents for the control of velvetbean caterpillars in soybean crops.
