scholarly journals Biological control of purple loosestrife (Lythrum salicaria) : factors affecting Galerucella pusilla and Galerucella calmariensis establishment in tidal areas

2009 ◽  
Author(s):  
Lynda Moore
Weed Science ◽  
1999 ◽  
Vol 47 (3) ◽  
pp. 360-365 ◽  
Author(s):  
Elizabeth J. Stamm Katovich ◽  
Roger L. Becker ◽  
David W. Ragsdale

Starch levels, used as a measure of plant stress, were not consistently reduced in root or crown tissue of purple loosestrife plants after 2 yr of severeGalerucella calmariensisorGalerucella pusilla(Coleoptera: Chrysomelidae) defoliation. Early in the season, defoliation fromGalerucellaspp. approached 100%, but the majority ofLythrum salicariaplants regrew by the end of August, resulting in an average reduction of 81% of the aboveground biomass compared to the control. The stress imposed byGalerucellaspp. defoliation was less than that achieved from more severe stress imposed by mechanical shoot clipping at 2- or 4-wk intervals from June to October. Both shoot-clipping treatments killed the majority of plants after one growing season.Galerucellaspp. feeding reduced plant stature, which may reduce competitiveness. However, considering the extensive carbohydrate reserves present in the large woody crowns ofLythrum salicaria, it will require in excess of 2 yr of consistent, severe leaf defoliation to cause plant mortality. A combination of stresses, such as winter crown injury, or other biological control agents in addition toGalerucellaleaf defoliation may be required for plant mortality.


1997 ◽  
Vol 129 (5) ◽  
pp. 937-948 ◽  
Author(s):  
Jason K. Diehl ◽  
N.J. Holliday ◽  
C.J. Lindgren ◽  
R.E. Roughley

AbstractIn 1994 and 1995 insects were collected from several sites in southern Manitoba, where purple loosestrife, Lythrum salicaria L., is dominant. Collection techniques included the use of trap plants, sweep netting, vacuum sampling, and hand collecting. Insects from 38 families were collected and grouped into four general feeding guilds: herbivores, predators, omnivores, and fungivores. Herbivores that directly fed on L. salicaria included Galerucella nymphaeae Linné (Coleoptera: Chrysomelidae), Myzus lythri (Schrank) (Homoptera: Aphididae), Poecilocapsus lineatus (Fabricius) (Hemiptera: Miridae), Kleidocerys resedae (Panzer) (Hemiptera: Lygaeidae), Ametastegia glabrata (Fallén) (Hymenoptera: Tenthredinidae), Orgyia leucostigma (Smith) (Lepidoptera: Lymantriidae), Lophocampa maculata (Harris) (Lepidoptera: Lymantriidae), Spilosoma virginica (Fabricius) (Lepidoptera: Arctiidae), Simyra henrici (Grote) (Lepidoptera: Noctuidae), Dichomeris ligulella (Hübner) (Lepidoptera: Gelechiidae), Melanchrapicta (Harris) (Lepidoptera: Noctuidae), Hyles galli (Rottenburg) (Lepidoptera: Sphingidae), and Biston betularia cognataria (Gn) (Lepidoptera: Geometridae). These herbivores cannot severely limit the density of purple loosestrife in southern Manitoba and any interactions with the introduced agents should be minimal. The predatory stink bug, Apoecilus bracteatus Fitch (Hemiptera: Pentatomidae), was identified as a potentially important predator of the introduced biological control agents, Galerucella pusilla Duftschmidt and Galerucella calmariensis (L.) (Coleoptera: Chrysomelidae).


2010 ◽  
Vol 100 (5) ◽  
pp. 605-611 ◽  
Author(s):  
P.A. Hambäck

AbstractAggregative responses are commonly observed in insects, including chrysomelids, affecting both individual and population growth rates. In two closely related chrysomelid beetles (Galerucella calmariensisandG. pusilla) feeding on purple loosestrife (Lythrum salicaria), recent studies suggest that male-produced pheromones may cause both inter- and intraspecific attraction. This paper further examines the causes and consequences of feeding aggregations in these species. Olfactometer studies confirm previous findings, showing cross-species attraction to damaged plants, but suggest that also damaged induced plant volatiles may be involved. In addition, the studies suggest that the cross-species attraction observed in previous studies have asymmetric effects on the two beetles.Galerucella pusillawas more attracted to damage byG. calmariensisthan to damage by conspecifics. Laboratory and field data suggest that feeding aggregations in these species increase pupal mass, at least at low to intermediate larval densities. This positive feedback may have important consequences for the spatiotemporal dynamics and as a consequence on the role of the two chrysomelid beetles on biological control of purple loosestrife.


1997 ◽  
Vol 11 (4) ◽  
pp. 824-827 ◽  
Author(s):  
Cory John Lindgren

Oviposition site preferences forGalerucella calmariensisandG. pusilla, biological weed control agents against purple loosestrife, were examined in 1994 and 1995. The leaves, stems, axils, and flower buds (G. pusilladid not oviposit on flower buds) were found to be the preferred oviposition sites. Oviposited egg masses may be used as a parameter within a biological control monitoring plan, providing information onGalerucellaestablishment and/or presence, estimating future population size, and providing biological control agent dispersal information. Monitoring for egg masses should concentrate on host plant leaves, where over 56% of all egg masses were oviposited.


Author(s):  
Angela Boag

Invasive species represent a major threat to global biodiversity and have multi‐million dollar impacts onagricultural productivity as well as the functioning of natural ecosystems. Biological control, theintroduction of the natural enemies of invading species, is a potentially cost‐effective and powerfulmanagement tool for controlling the spread and impact of exotic organisms. However, the monitoringcomponent of biocontrol initiatives is rarely adequate to determine their success, impeding theimprovement of biocontrol techniques. In order to determine the efficacy of the biocontrol beetlesintroduced to control purple loosestrife (Lythrum salicaria), an invasive wetland plant in Ontario, 52 L.salicaria populations were surveyed in eastern and central Ontario in August and September 2009. Threepopulation types were surveyed, those in which the release of Galerucella species biocontrol beetles hadanecdotally been effective, anecdotally ineffective, and those in which beetles had never beenpurposefully released.  The level of herbivory damage inflicted by the biocontrol beetles was recorded, aswell as plant height, flower number, and measures of stand density.  It was determined that thebiocontrol beetles have spread throughout Ontario, and are inflicting a moderate level of damage onpurple loosestrife populations. However, significant variation exists among populations in thesemeasures, and levels of damage were not significantly different between the three site types. Thisindicates that a variety of ecological factors influence the efficacy of biocontrol, and it is recommendedthat the purple loosestrife biocontrol program be more intensively monitored in future so that it mayinform subsequent initiatives in Canada.


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