Journal of Nematology (2005) 37, p. 367 (Duncan et al.)

L.W. Duncan, J.H. Graham, F. El-Borai and D.L. Porazinska (2005)
Trophic cascades and non-target effects of augmenting entomopathogenic nematode communities
Journal of Nematology 37 (3), 367-367
44th Annual Meeting, Society of Nematologists, Fort Lauderdale, Florida, 9-13 July, 2005
Abstract: Augmentative biological control is employed to increase the mortality of a pest by temporarily increasing the numbers of a biocontrol agent beyond its equilibrium density. Implicit in this tactic is the expectation that numbers of the biocontrol agent will eventually decline to the equilibrium state, due in part to the effects of natural enemies. Trophic cascades resulting from EPN augmentation could affect pest control variously, depending on the strength of specific density dependent responses in the food web. Two weeks after augmenting the entomopathogenic nematodes (EPN) beneath citrus trees to control soilborne larvae of the weevil Diaprepes abbreviatus, there were significant increases in mortality of sentinel weevil larvae, prevalence of the nematophagous fungi Arthrobotrys sp. and Dactylaria sp., and prevalence of free-living bactivorous nematodes in cadavers of sentinel weevils. Six weeks following EPN augmentation, significantly fewer sentinel weevil larvae died in augmented compared to non-augmented plots. Application of composted manure as a mulch layer beneath trees decreased the prevalence of nematophagous fungi, increased the prevalence of endemic EPN, and increased the mortality of sentinel weevil larvae. In the laboratory, addition of S. riobrave to soil from the orchard increased the mortality of both S. riobrave and S. diaprepesi that were added to the soil seven days later. At the end of two weeks, greater numbers of nematophagous fungi and fewer EPN remained in soil that was augmented at the beginning of weeks one and two, than in soil that was augmented only in week two. These effects did not occur in soil that was air-dried to disrupt fungal activity prior to the experiment. Heterorhabditis zealandica was significantly less affected by preaugmentation than were the steinernematid species. Apparently, effects of the post-application biology of EPN on biological control can be modulated in important ways by selecting appropriate species and cultural practices.
Database assignments for author(s): Larry W. Duncan, Fahiem E. El-Borai

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation
population dynamics/epizootiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Diaprepes abbreviatus	Citrus (genus)
Steinernema riobrave/Xenorhabdus cabanillasii (entomopathogen)	Diaprepes abbreviatus	Citrus (genus)
Heterorhabditis zealandica (entomopathogen)