Feeding on Host Plants with Different Concentrations and Structures of Pyrrolizidine Alkaloids Impacts the Chemical-Defense Effectiveness of a Specialist Herbivore

Abstract

Sequestration of chemical defenses from host plants is a strategy widely used by herbivorous insects to avoid predation. Larvae of the arctiine moth Utetheisa ornatrix feeding on unripe seeds and leaves of many species of Crotalaria (Leguminosae) sequester N-oxides of pyrrolizidine alkaloids (PAs) from these host plants, and transfer them to adults through the pupal stage. PAs confer protection against predation on all life stages of U. ornatrix. As U. ornatrix also uses other Crotalaria species as host plants, we evaluated whether the PA chemical defense against predation is independent of host plant use. We fed larvae from hatching to pupation with either leaves or seeds of one of eight Crotalaria species (C. incana, C. juncea, C. micans, C. ochroleuca, C. pallida, C. paulina, C. spectabilis, and C. vitellina), and tested if adults were preyed upon or released by the orb-weaving spider Nephila clavipes. We found that the protection against the spider was more effective in adults whose larvae fed on seeds, which had a higher PA concentration than leaves. The exceptions were adults from larvae fed on C. paulina, C. spectabilis and C. vitellina leaves, which showed high PA concentrations. With respect to the PA profile, we describe for the first time insect-PAs in U. ornatrix. These PAs, biosynthesized from the necine base retronecine of plant origin, or monocrotaline- and senecionine-type PAs sequestered from host plants, were equally active in moth chemical defense, in a dose-dependent manner. These results are also partially explained by host plant phylogeny, since PAs of the host plants do have a phylogenetic signal (clades with high and low PA concentrations in leaves) which is reflected in the adult defense.

The conservation of native, lowland Indonesian Begonia species (Begoniaceae) in Bogor Botanic Gardens

“…Related to MIC and MBC several medicinal plants of India (Patil et al 2012), Korea (Kim et al 2008b), and Indonesia (Batubara et al 2009) were reported to have MIC and MBC potential against P. acnes. The inhibition of leaf extract from C. pallida may cause by some compounds contained in this plant such as pyrrolizidine alkaloids (Martins et al 2015), peptides (Pelegrini et al 2009), flavonoids (Ko et al 2004) or others compound. The V. pinnata extracts inhibited P. acnes can be affected by iridoids, flavonoids, ecdysteroids, pinnata sterones or others compound (Ata et al 2009;Meena et al 2010).…”

Pyrrolizidine Alkaloids in the Pericopine MothScearctia figulina(Erebidae: Arctiinae): Metabolism and Chemical Defense

“…14,15,[27][28][29] We assigned the absolute stereochemistry of PAs based only in retention index of chiral PAs reported in the literature. 20,27 Chemical defense of Scearctia figulina: predation bioassays…”

“…11 Other interesting PA pathways in arctiine moths are the de novo biosynthesis of insect ester alkaloids (insect PAs) and the stereochemical inversion of 7R configuration to 7S pyrrolizidine rings. [14][15][16] Both biochemical mechanisms are involved in the biosynthesis of dihydropyrrolizine male sexual pheromones. [16][17][18][19] Insect PAs are esters biosynthesized from plant-acquired necine bases with necic acids of insect origin, and it has been suggested that they are biosynthesized via transesterification of plant PAs.…”

“…16,20 Callimorphine type PAs were found in the Arctiina Arctia caja, Creatonotos transiens, Estigmene acrea, and Grammia geneura, in the Callimorphina Callimorpha dominula and Tyria jacobaea, and in the Pericopina Gnophaela latipennis and Hyalurga syma. [14][15][16] PAs of the creatonotine type were found in the Arctiina Creatonotos transiens, Estigmene acrea, and Grammia geneura, and in the Callimorphina Utetheisa ornatrix. 16 Insect PAs were not found in the Callimorphina Nyctemera annulata.…”

“…The Ethics Committee for Animal Use of the University of Campinas approved all experimental procedures. Chicks were donated to free range farms by the Martins and Trigo 1439 Vol. 27, No.…”