Ecological Entomology (2013) 38, 117-122

S. Raghu, Matthew F. Purcell and Anthony D. Wright (2013)
Catchment context and the bottom-up regulation of the abundance of specialist semi-aquatic weevils on water hyacinth
Ecological Entomology 38 (1), 117-122
Abstract: 1. Bottom-up regulation is prevalent in plant-herbivore interactions and is thought to be particularly important in the case of aquatic plants and their specialist insect herbivores.
2. Recently published mesocosm studies have shown that the abundance of specialist Neochetina weevils, N. bruchi and N. eichhorniae, on water hyacinth (Eichhornia crassipes) are principally under the influence of nutrients in plant tissues.
3. We examined historical patterns of the abundance of these species of semi-aquatic weevils in two water bodies from catchments with significantly different nutrient loads in subtropical Australia to test the validity of the published conceptual model of bottom-up regulation.
4. Our results revealed that these weevils are indeed under bottom-up regulation under field conditions. However, the nature of this regulation appears to be influenced by the broader catchment context of the water hyacinth-infested water body, with plant tissue nutrients influencing weevil abundance more in the catchment with lower nutrient run-offs.
5. Our findings reaffirm the importance of bottom-up regulation in plant-insect interactions, add to the growing evidence of indirect effects spanning terrestrial and aquatic ecosystems, and inform management of water hyacinth using these weevils as biocontrol agents.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Matthew Purcell, A.D. (Tony) Wright, Sathyamurthy Raghu

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

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pontederia crassipes (weed)		Australia (NT+QLD)
Neochetina eichhorniae (weed bioagent)	Pontederia crassipes (weed)		Australia (NT+QLD)
Neochetina bruchi (weed bioagent)	Pontederia crassipes (weed)		Australia (NT+QLD)