José Roberto Trigo

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Larvae of Chrysomya albiceps (Wiedemann) and Chrysomya putoria (Wiedemann) (Diptera: Calliphoridae) were reared on tissues from rabbits administered twice the lethal dosage of diazepam in order to study the effects of this drug on the development of these two species. The rabbits were given 50mg of diazepam via ear vein infusion. From 18 to 54h, larvae(More)
Brugmansia suaveolens (Solanaceae) contains tropane alkaloids (TAs), which can act as chemical defenses. Selective pressures might modulate the allocation of alkaloids within the plant, as postulated by optimal-defense theory. By tracing scopolamine, the most abundant TA in this species, we found that scopolamine in an artificial diet, in concentrations(More)
In Brazil, four populations of Lutzomyia longipalpis each producing different sex pheromones are recognised. It has been suggested that these chemotype populations represent true sibling species. In this study we present the results of an analysis, by coupled gas chromatography-mass spectrometry, of the pheromones of males L. longipalpis from two different(More)
Pyrrolizidine alkaloids (PAs), mainly those with a 1,2-double bond in the necine base moiety (=1,2-dehydropyrrolizidines), constitute a class of well studied compounds with respect to their flux through different trophic levels. Plants belonging to various clades (e.g. Echiteae, Eupatorieae and Senecioneae, Boraginaceae, and Crotalarieae) biosynthesize PAs(More)
Larvae of the ithomiine butterflyPlacidula euryanassa sequester tropane alkaloids (TAs) from the host plantBrugmansia suaveolens and pass them through the pupae to freshly emerged adults. Wild caught adults also show in their tissues, variable amounts of pyrrolidizine alkaloids (PAs), probably sequestered from variable plant sources and subject to dynamics(More)
Local adaptation of parasites to their hosts due to coevolution is a central prediction of many theories in evolutionary biology. However, empirical studies looking for parasite local adaptation show great variation in outcomes, and the reasons for such variation are largely unknown. In a previous study, we showed adaptive differentiation in the arctiid(More)
Pyrrolizidine alkaloids (PAs), acquired by adults or larvae of Danainae and Ithomiinae butterflies and Arctiidae moths from plants, protect these lepidopterans against predators and are biosynthetic precursors of male sex pheromones. The investigation of PAs in many species of wild-caught adults of Ithomiinae showed lycopsamine (1) [(7R)-OH, (2′S)-OH,(More)
Plant defensive compounds may be a cost rather than a benefit when plants are attacked by specialist insects that may overcome chemical barriers by strategies such as sequestering plant compounds. Plants may respond to specialist herbivores by compensatory growth rather than chemical defense. To explore the use of defensive chemistry vs. compensatory growth(More)
The alkaloid extract of Senecio brasiliensis inflorescences contain a mixture of the pyrrolizidine alkaloids (PA) senecionine, integerrimine, retrorsine, usaramine and seneciphylline. We evaluated this PA mixture on preventive antiulcerogenic effects on standard rodent models of induced gastric and duodenal ulcers. In the HCl/ethanol,(More)
Lysine has long been recognized as an essential amino acid for humans and the lack or low supply of this compound in the diet may lead to mental and physical handicaps. Since lysine is severely restricted in cereals, the most important staple food in the world, the understanding of its biological roles must be a major concern. Here we show that lysine is an(More)