Toxicity and synergism in the feeding deterrence of some coumarins on Spodoptera frugiperda Smith (Lepidoptera: Noctuidae).
The phagodepression activity of five coumarins (= 2H-1-benzopyran-2-ones), 6-hydroxy-7-isoprenyloxycoumarin (1), 6-methoxy-7-isoprenyloxycoumarin (2), 6,7-methylenedioxycoumarin (3), 5-methoxy-6,7-methylenedioxycoumarin (4), and 6-methoxy-7-(2-hydroxyethoxy)coumarin (5), from the Argentine native herb Pterocaulon polystachyum, was tested against Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae. Two analogs, scopoletin (6) and 2-methoxy-2-methyl-3,4,5,6,7,8-hexahydro-3H-chromen-5-one (7), synthesized in our laboratory, were also evaluated for comparison. The compounds were added to an artificial diet at doses ranging from 50 to 200 microg per g of diet. Natural coumarins induced 100% of phagodepression when 200 microg were added per g of diet. Binary equimolar mixtures of the natural coumarins were phagodepressors against S. frugiperda surpassing the expected additive responses, indicating that these compounds can act synergistically against S. frugiperda larvae. Compounds 1 and 3 (non-methoxylated coumarins), and the equimolar mixture of both, displayed the strongest phagodepression. Additionally, 50 microg/g of 1 and 3 incorporated to the larval diet caused 80 and 50% of pupal mortality, respectively, while a 100 microg/g dose of compounds 2, 4, 6, and 7 produced 60, 50, 10, and 80% pupal mortality, respectively. Larval growing rate during the early larval instars was significantly reduced by treatments with the methylenedioxycoumarins 3 and 4. Coincidentally, the larval period duration was significantly increased by the latter compounds.
Vera
Nancy
N
Departamento de Química Orgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, 4000 Tucumán, Argentina.
Popich
Susana
S
Luna
Liliana
L
Cravero
Raquel
R
González Sierra
Manuel
M
Bardón
Alicia
A
D000818:Animals; D002755:Choice Behavior / Q000187:drug effects / Q000502:physiology; D003374:Coumarins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D004357:Drug Synergism; D005247:Feeding Behavior / Q000187:drug effects* / Q000502:physiology; D035264:Flowers; D007814:Larva / Q000187:drug effects / Q000502:physiology; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity; D018515:Plant Leaves; D028321:Plant Preparations / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity; D018411:Spodoptera / Q000187:drug effects* / Q000502:physiology
D003374:Coumarins; D010936:Plant Extracts; D028321:Plant Preparations; C030123:coumarin