Biocontrol Science and Technology (2019) 29, 615-625

Ellyn V. Bitume, Patrick J. Moran and René F.H. Sforza (2019)
Impact in quarantine of the galling weevil Lepidapion argentatum on shoot growth of French broom (Genista monspessulana), an invasive weed in the western U.S.
Biocontrol Science and Technology 29 (7), 615-625
Abstract: In weed biocontrol, there is a need for pre-release efficacy assessments for potential agents. Genista monspessulana ((L.) L. A. S. Johnson (Fabaceae), French broom) is an invasive perennial shrub in the western U.S. The galling weevil Lepidapion argentatum Gerstaecker is a potential biocontrol agent. The impact of increasing weevil density on galling damage, plant height, width, leaf damage, and relative growth rate (RGR) was assessed in greenhouse experiments on two to three-month-old seedlings infested with either one or three weevils. Infestation by three female weevils caused 48% more galls producing 27% more larvae than did infestation with one female while causing only 1% leaf damage and no difference in total leaf area. Infestation with multiple weevils caused a 55% and 29% decrease in plant height and canopy width respectively, while single-weevil infestation decreased height by 32% and width to the same degree as for multiple weevils. The RGR of seedlings infested with three weevils was three times slower than the controls, while growth was reduced 2-fold by single-weevil infestation. Reductions in plant size and growth rate induced by weevil galling could reduce plant competitive survival to reproduction and also plant population dispersal as seedlings. Our results suggest that L. argentatum has the potential to cause impact to French broom seedlings if released in the invasive range.
(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): Patrick J. Moran, René Sforza

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution
evaluation - screening - selection

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Genista monspessulana (weed)		U.S.A. (SW)
Lepidapion argentatum (weed bioagent)	Genista monspessulana (weed)