A 20-year evaluation of successes with biological control of spotted knapweed (Centaurea stoebe) in Colorado

2021 ◽  
Vol 159 ◽  
pp. 104631
Author(s):  
T.R. Seastedt ◽  
D.G. Knochel
Keyword(s):  
Biological Control ◽  
Spotted Knapweed ◽  
Centaurea Stoebe

scholarly journals Biological control and precipitation effects on spotted knapweed (Centaurea stoebe): empirical and modeling results

Ecosphere ◽  
2013 ◽  
Vol 4 (7) ◽  
pp. art80 ◽  
Author(s):  
Anastasia Maines ◽  
David Knochel ◽  
Timothy Seastedt
Keyword(s):  
Biological Control ◽  
Spotted Knapweed ◽  
Centaurea Stoebe

Distribution of Urophora affinis and U. quadrifasciata, Two Flies Introduced for Biological Control of Spotted Knapweed (Centaurea maculosa) in Montana

Weed Science ◽  
1987 ◽  
Vol 35 (2) ◽  
pp. 145-148 ◽  
Author(s):  
Jim M. Story ◽  
Robert M. Nowierski ◽  
Keith W. Boggs
Keyword(s):  
United States ◽  
Biological Control ◽  
North America ◽  
Positive Relationship ◽  
The United States ◽  
Centaurea Maculosa ◽  
Spotted Knapweed ◽  
Seed Head ◽  
Strong Positive Relationship ◽  
Southeasterly Direction

A survey was conducted at 88 sites in Montana in 1984 and 1985 to determine the distribution of Urophora affinis Frauenfeld and U. quadrifasciata (Meigen), two seed head flies released on spotted knapweed (Centaurea maculosa Lam. # CENMA) in North America. U. affinis, released in Montana during 1973 to 1977, was found at 40 of the 88 sites. The fly was concentrated within a short radius (about 5 to 8 km) of release sites, even at sites having well-established populations. U. quadrifasciata, released in British Columbia in 1972, but not in the United States, was found at 84 sites. The data suggest that the fly entered the state in the northwest corner and dispersed in a southeasterly direction. There was a strong positive relationship between mean number of galls per seed head and percent infestation for both fly species.

METZNERIA PAUCIPUNCTELLA ZELLER (LEPIDOPTERA: GELECHIIDAE), A MOTH INTRODUCED AGAINST SPOTTED KNAPWEED: ITS FEEDING STRATEGY AND IMPACT ON TWO INTRODUCED UROPHORA SPP. (DIPTERA: TEPHRITIDAE)

1991 ◽  
Vol 123 (5) ◽  
pp. 1001-1007 ◽  
Author(s):  
J.M. Story ◽  
K.W. Boggs ◽  
W.R. Good ◽  
P. Harris ◽  
R.M. Nowierski
Keyword(s):  
Biological Control ◽  
Seed Dispersal ◽  
Pacific Northwest ◽  
Biocontrol Agent ◽  
Feeding Strategy ◽  
Centaurea Maculosa ◽  
Spotted Knapweed ◽  
Seed Head ◽  
The Pacific ◽  
Normal Seed

AbstractMetzneria paucipunctella Zeller is a seed head moth introduced for biological control of spotted knapweed, Centaurea maculosa Lamarck, in the Pacific Northwest. A cage study was conducted in Montana in 1987 and 1988 to assess the feeding strategy of the M. paucipunctella larva and its impact on two seed head flies, Urophora spp., also introduced on spotted knapweed. Each moth larva destroyed an average of 8.13 knapweed seeds. Most of the seeds were destroyed prior to seed dispersal in early September but the remaining seeds were attacked in the spring of the following year. Each larva tied an average of 7.0 seeds with silk webbing which allowed for feeding long after normal seed dispersal. Seed survival in cages containing both the moth and the two fly species (4.71 seeds per head) was significantly less than in fly-only cages (9.75 seeds per head). The moth larvae caused extensive mortality to the two Urophora species, especially during the spring months. Moth-caused mortality to U. affinis larvae increased from 19% during June through October to 67% in May of the following year. Mortality to U. quadrifasciata also occurred but did not increase significantly in the spring. Data from 10 field sites showed very little association between M. paucipunctella and the two Urophora species which suggests that the unnatural conditions associated with the cages did not increase the incidence of joint moth and fly attack to individual seed heads. The moth is a valuable biocontrol agent as it is contributing significantly to the overall consumer pressure on spotted knapweed seed heads.

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