PAs in Chromolaena odorata (Asteraceae)

Thoden TC, Boppré M, Hallmann J (2007) Pyrrolizidine alkaloids of Chromolaena odorata act as nematicidal agents and reduce infection of lettuce roots by Meloidogyne incognita. Nematology 9: 343-349. lesen / read

1,2-dehydropyrrolizidine alkaloids (PAs) represent a class of secondary plant compounds that are active in defence against herbivory. They are present in Chromolaena odorata, one of the most invasive weeds of Asia and Africa. In-vitro studies demonstrate that pure PAs from C. odorata roots have nematicidal effects to the root-knot nematode Meloidogyne incognita, even at concentrations of 70350 ppm. In-vivo experiments show that mulch or aqueous crude extracts from C. odorata roots reduce the infection of lettuce by M. incognita. Thus, the use of PA containing plants appears as a valuable element for integrated nematode management.

Boppré M, Fischer OW (1999) Harlekinschrecken (Orthoptera: Zonocerus) Schadinsekten der besonderen Art. Gesunde Pflanzen 51: 141-149. lesen / read

Heuschrecken der Gattung Zonocerus sequestrieren Pyrrolizidin-Alkaloide (PA) nicht nur von bestimmten Futterpflanzen, sondern auch unabhängig vom Nahrungserwerb. Sie speichern diese sekundären Pflanzeninhaltsstoffe zum Schutz vor Antagonisten. Mit Blüten des eingeschleppten Unkrauts Chromolaena odorata (Asteraceae) haben Trockenzeit-Populationen eine neue und nahezu unerschöpfliche Quelle für PA und erreichen damit eine höhere Fitness, was sie zu Schädlingen in Land- und Forstwirtschaft macht. Das chemoökologische Verständnis um die "pharmakophage" Beziehung von Zonocerus zu PA ermöglicht das selektive Ködern einer schädlichen Heuschreckenart und liefert den Schlüssel für ein flexibel gestaltbares, umweltgerechtes und ökonomisch vertretbares Management der Harlekinschrecken. Das Beispiel erläutert ferner verschiedene grundsätzlich relevante Aspekte zur Biologie und zum Management von Insekten.

Fischer OW, Boppré M (1997) Chemoecological studies reveal causes for increased population densities of Zonocerus (Orth.: Pyrgomorphidae) and offer new means for management. Pp 265-279 in Krall S, Peveling R, Ba Diallo D (eds) New Strategies in Locust Control. CH-Basel: Birkhäuser Verlag. lesen / read

Grasshoppers of the genus Zonocerus sequester pyrrolizidine alkaloids (PAs) not only from certain nutritional host plants but also independent of dietary requirements. Storage of PAs serves protection of the insects from antagonists, and thus aquisition of these secondary plant chemicals modulates the grasshopper's population dynamics. Flowers of the introduced weed Chromolaena odorata (Asteraceae) represent a novel and inexhaustable resource of PAs but only for populations in the dry-season. Evidence is provided that better performance related to the presence of Chromolaena is a reason that dry-season populations became a serious pest in coincidence with the spread of the weed. The chemoecological knowledge on the Zonocerus-PA relationship permits the development of selective baits, and with environmentally sound and cost-efficient application of insecticides the species can be lured to its doom. Multiple means for employing PA-baits within IPM concepts are possible, i.e. strategies of population management can be tailored according to actual demands and conditions. Apart from fighting the grasshopper in individual farms, a general reduction of Zonocerus populations is suggested to lower mean levels of abundance in areas with frequent upsurges; this could be done by combining PA-baits with mycoinsecticide technology.

Biller A, Boppré M, Witte L, Hartmann T (1994) Pyrrolizidine alkaloids in Chromolaena odorata. Chemical and chemoecological aspects. Phytochemistry 35: 615-619.lesen / read

The tropical weed Chromolaena odorata contains the N-oxides of five pyrrolizidine alkaloids (PAs): 7- and 9-angeloylretronecine, intermedine, rinderine and 3'-acetylrinderine. Highest concentrations occur in roots and mature flower heads, while leaves and stems are almost devoid of alkaloids, and no PAs are present in nectar. The polyphagous grasshopper Zonocerus variegatus sequesters intermedine and rinderine from Chromolaena flowers and transforms up to 20% of these PAs into lycopsamine and echinatine, respectively, by inversion of configuration at C-3'. Pure rinderine injected into the haemolymph of Zonocerus is partly converted into intermedine, indicating inversion of configuration at C-7.

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PAs in Chromolaena odorata (Asteraceae)