Effects of plants containing pyrrolizidine alkaloids on the northern root-knot nematode Meloidogyne hapla

Abstract

1,2-Dehydropyrrolizidine alkaloids (PAs), known to be nematotoxic in vitro, represent a class of secondary plant metabolites from hundreds of plant species worldwide. Pot experiments with the commercially available PA-containing plants Ageratum houstonianum, Borago officinalis, Senecio bicolor, and Symphytum officinalis demonstrate that Meloidogyne hapla is not per se repelled by these plants as all species were infested with nematodes. However, the development of M. hapla juveniles was completely suppressed on A. houstonianum and S. bicolor. Soil in which A. houstonianum and S. bicolor were cultivated and incorporated contained 200-400 times less nematodes than soil treated with Lycopersicon esculentum.Depending on their qualitative composition of PAs at least some of these plants thus appear to be valuable tools for integrated root-knot nematode management.

Evaluation of the repellent and insecticidal activities of the leaf, stem and root powders of siam weed (<i>Chromolaena odorata</i>) against the Cowpea Beetle, <i>Callosobruchus maculatus</i>

“…Alkaloids are complex compounds that occur naturally in plants and are toxic to insects (Fatoki and Fawole, 2000). The alkaloids present in C. odorata have shown nematostatic and nematicidal effects on plantparasitic nematodes (Thoden et al, 2009;Agaba and Fawole, 2014). A class of metabolites, the 1,2-dehydropyrrolizidine alkaloids are well-known feeding deterrents against herbivores and are toxic to a wide range of non-adapted animals (Narberhaus et al, 2005;Thoden et al, 2009); and may have potential for insect pest management.…”

“…The alkaloids present in C. odorata have shown nematostatic and nematicidal effects on plantparasitic nematodes (Thoden et al, 2009;Agaba and Fawole, 2014). A class of metabolites, the 1,2-dehydropyrrolizidine alkaloids are well-known feeding deterrents against herbivores and are toxic to a wide range of non-adapted animals (Narberhaus et al, 2005;Thoden et al, 2009); and may have potential for insect pest management. Flavonoids are a class of phenolic compounds that have anti-feeding and attracting deterrent properties, thus are toxic to insects, fungi, nematodes and weeds (Carlsen and Fomsgaard, 2008).…”

Plants producing pyrrolizidine alkaloids: sustainable tools for nematode management?

“…However, in all studies on Crotalaria so far, the mechanism of nematode reduction has not been assigned to PAs. In our own studies, in addition to Crotalaria, other PA-producing plant species such as dusty miller (Senecio bicolor) or floss flower (Ageratum houstonianum) significantly suppressed population densities of Meloidogyne hapla when used for in situ mulching (Thoden et al, 2009b). Furthermore, M. incognita infestation of lettuce could be lowered significantly when nematodeinfested soil was either treated with mulch or aqueous extracts from roots of Siam weed (Chromolaena odorata), another PA-producing plant (Biller et al, 1994;Thoden et al, 2007).…”

Effects of pyrrolizidine alkaloids through different trophic levels

“…In some cases the performance is negatively affected (Vrieling et al 1991;Thoden et al 2009b). In other cases, consuming leaves with low PA concentration, despite their low nutritional content, has also been reported (Van Dam et al 1995) (Table 1).…”