Naturally Occurring Nematicides

Abstract

This review of naturally occurring phytochemicals with biological activity against plant-parasitic nematodes focuses on several diverse classes of compounds, including polythienyls, alkaloids, phenolics, polyacetylenes, fatty acids, terpenoids, and others. The nematotoxic mode of action and physiological role of most of these compounds in plants are unknown, although some are synthesized in response to nematode infection. Only a few plant families, primarily the Asteraceae and Fabaceae, have been examined for existence of nematotoxic substances. In a few cases, synthetic analogs of naturally occurring compounds have been synthesized and have possessed stronger biological activity than the naturally occurring ones. Enhanced research and development of phytochemical nematicides and analogs could provide safe, selective compounds for minimizing the multibillion dollar annual losses inflicted by phytoparasitic nematodes in the U.S. Currently available chemicals for management of phytoparasitic nematodes are not only expensive but can also adversely affect the environment or human health (1-3). Consequently, several nematicides have been deregistered or restricted in use during the past decade, and others could face similar restrictions. Because phytoparasitic nematodes inflict annual agricultural losses of 6 billion dollars in the U.S. and 77 billion dollars in the world (4), better management tools are needed urgently.Because higher plants could be expected to be a rich reservoir of interesting compounds with biological activity against phytoparasitic nematodes, isolation and identification of naturally occurring phytochemicals with biological activity against nematodes would be a logical first step for development of new, environmentally safe nematicides. Indeed, higher plants are being increasingly examined as sources for novel compounds with activity against animal-parasitic This chapter not subject to U.S.

Yield of ‘Superior’ potatoes (Solanum tuberosum) and dynamics of root-lesion nematode (Pratylenchus penetrans) populations following “nematode suppressive” cover crops and fumigation

“…Nematicidal chemistry including nitrogenous soil amendments has been reviewed by several authors (Akhtar and Mahmood 1994;Chitwood 1993;Rodriguez-Kabana 1986;Rodriguez-Kabana et al 1987); however, many reports are on species otherthan P. penetrans. The possibility that P. penetrans is not controlled or is poorly controlled directly by the cover crops tested, is consistent with our results.…”

“…Some plants or plant parts can suppress various nematode species (Akhtar and Mahmood 1994;Chitwood 1993;Davis et al 1989Davis et al , 1991Dunn and Mai 1973;Rodriguez-Kabana 1986). Selected high glucosinolate cultiva rs of Brassica spp.…”

Investigations into the Biochemical Basis for Nematode Resistance in Roots of Three Musa Cultivars in Response to Radopholus similis Infection

“…In comparison, Yangambi Km5 always produces well developed root lesions even though nematode numbers remain low (Collingborn, unpublished). Several different classes of compounds have nematicidal properties, e.g., fatty acids, polythienes, terpenoids, alkaloids, isoflavonoids, and phenolics (Chitwood, 1993;Baldridge et al, 1998). Plants synthesize a wide variety of preinfectional and postinfectional compounds which are active against root nematodes (Giebel, 1974;Mace and Howell, 1974;Binks, 1996;Luis, 1998).…”

NMR Analysis Reveals a Wealth of Metabolites in Root-Knot Nematode Resistant Roots of Citrullus amarus Watermelon Plants

“…Lower concentrations of secondary metabolites observed in domesticated plants is likely the result of selection for desirable horticultural qualities but not for secondary metabolites that play an important role in plant defense against biotic or abiotic stress (Hadacek and Günther, 2002). Chitwood (1993Chitwood ( , 2002 elucidated several groups of metabolites associated with resistance against nematodes, including polythienyls, alkaloids, phenolics, polyacetylenes, fatty acids, and terpenoids. It is likely that the resistance of CA PIs to RKN Levi, 2003, 2007) is the result of a naturally occurring secondary metabolite(s).…”