Influence of Stem Nematode Infestation on Bacterial Wilt Reaction and Forage Yield of Alfalfa Varieties

Hawn, E. J.; Hanna, M. R.

doi:10.4141/cjps67-035

Cited by 18 publications

(6 citation statements)

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“…Nematodes can alter the performance of arthropods and other plant pathogens on shared host plants (Hawn and Hanna 1967 ; Wondafrash et al 2013 ). Here, we found that stem nematodes increased aphid abundance on alfalfa.…”

Section: Discussionmentioning

confidence: 99%

“…This is in contrast to the studies that tested the effects of root-feeding nematodes on aphid abundance aboveground (examples in McCarville et al 2012 ; Wondafrash et al 2013 ). One of a few studies examining stem nematodes investigated the impact of stem nematodes on bacterial wilt ( Corynebacterium insidiosum ) and found that nematodes also can increase the susceptibility of alfalfa varieties to this bacterium (Hawn and Hanna 1967 ). An example on melon plants shows that other plant pathogens also can enhance aphid abundance (Moran 1998 ).…”

Section: Discussionmentioning

confidence: 99%

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Stem Nematode Counteracts Plant Resistance of Aphids in Alfalfa, Medicago Sativa

Spears

2014

J Chem Ecol

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Plants are exploited by a diverse community of insect herbivores and phytopathogens that interact indirectly through plant-mediated interactions. Generally, plants are thought to respond to insects and pathogens through different defensive signaling pathways. As plants are selected for resistance to one phytophagous organism type (insect vs. pathogen) in managed systems, it is not clear how this selection may affect community interactions. This study examined the effect of nematode-resistant varieties on aphid (Acyrthosiphon pisum) suppression, and then determined how infection by the stem nematode, Ditylenchus dipsaci, mediated ecological effects on aphids and on plant defense proteins. Four alfalfa (Medicago sativa) varieties were selected with resistance to nematodes only (+,−), aphids only (−,+), nematodes and aphids (+,+), and susceptibility to nematodes and aphids (−,−). Field and greenhouse experiments were conducted to isolate the effect of nematode infection and aphid abundance on each variety. We found that varieties resistant to nematode, regardless of aphid resistance, had the lowest aphid counts, suggesting possible cross-resistance. Aphid abundance, however, increased when plants were exposed to nematodes. Resistant varieties were associated with elevated saponins but these compounds were not affected by insect or pathogen feeding. Concentrations of peroxidases and trypsin inhibitors, however, were increased in nematode resistant varieties when exposed to nematodes and aphids, respectively. The patterns of plant defense were variable, and a combination of resistance traits and changes in nutrient availability may drive positive interactions between nematodes and aphids aboveground.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Stem Nematode Counteracts Plant Resistance of Aphids in Alfalfa, Medicago Sativa

Spears

2014

J Chem Ecol

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“…It was suggested that the nematode could transmit the bacteria, as numerous bacterial cells were observed on the nematode after artificial inoculation. This nematode was able to decrease bacterial wilt resistance in lucerne by causing physiological or biochemical change, but not in all cultivars, (Hawn and Hanna, 1967).…”

Section: Conditions Favouring Disease Developmentmentioning

confidence: 92%

“…This effect was found independent of whether the bacteria or the nematode came first (Griffin and Hunt, 1972). This nematode was able to decrease bacterial wilt resistance in lucerne by causing physiological or biochemical change, but not in all cultivars, (Hawn and Hanna, 1967). Dissemination of C. michiganensis subsp.…”

Section: Conditions Favouring Disease Developmentmentioning

confidence: 95%

“…The bacterium is carried by water and benefits from mowing, freezing and thawing wounds (Koehler and Jones, 1932). It was shown that the incidence of infection is increased in the presence of this nematode (Hawn and Hanna, 1967) and by Meloidogyne hapla (Hunt et al, 1971). Nematode transmission by Ditylenchus dipsaci has been shown (Hawn, 1963(Hawn, , 1971.…”

Section: Infectionmentioning

confidence: 99%

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