Influence of Seed Head–Attacking Biological Control Agents on Spotted Knapweed Reproductive Potential in Western Montana Over a 30-Year Period

2008 ◽  
Vol 37 (2) ◽  
pp. 510-519 ◽  
Author(s):  
Jim M. Story ◽  
Lincoln Smith ◽  
Janelle G. Corn ◽  
Linda J. White
Keyword(s):  
Biological Control ◽  
Reproductive Potential ◽  
Western Montana ◽  
Spotted Knapweed ◽  
Biological Control Agents ◽  
Seed Head

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.

Biological Control of Diffuse Knapweed (Centaurea diffusa) and Spotted Knapweed (C. maculosa)

Weed Science ◽  
1982 ◽  
Vol 30 (1) ◽  
pp. 76-82 ◽  
Author(s):  
Donald M. Maddox
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Reproductive Potential ◽  
Control Agent ◽  
Flower Head ◽  
Spotted Knapweed ◽  
Centaurea Diffusa ◽  
Weedy Species ◽  
Diffuse Knapweed ◽  
Number Of Seeds

Diffuse knapweed (Centaurea diffusa Lam.) and spotted knapweed (C. maculosa Lam.) presently infest approximately 1.5 million ha of pasture and rangeland in Washington, Montana, Idaho, Oregon, and California. The serious losses caused on lands where returns from herbicidal control are marginal or less prompted the testing and introduction of two strains of a seed-head fly (Urophora affinis Frlfld.) as a biological-control agent in these states. Over 27 000 flies were released in about equal numbers on both weeds during the years 1974 to 1977 and in 1979 and 1980. The fly became established in all states where it was released. The adult was found to disperse over 76 m from release point from 1974 to 1976, and to reduce the number of seeds per flower head in sampled heads by 80% in northern Washington and over 64% at the Heppner, Oregon site. A newly released moth (Metzneria paucipunctella Zell.) and a root-boring beetle (Spbenoptera jugoslavica Obenb.) are expected to cause additional pressure on these plants. The reproductive potential of the knapweeds is such that more natural enemies will be needed to provide enough stress to reduce these weedy species to an acceptable level.

Detection and Identification of Viruses in Economically Important Insects

2000 ◽  
Vol 6 (S2) ◽  
pp. 666-667
Author(s):  
E. L. Styer ◽  
J. J. Hamm
Keyword(s):  
Biological Control ◽  
Insect Pests ◽  
Reproductive Potential ◽  
Biological Control Agents ◽  
Control Programs ◽  
Detection And Identification ◽  
Zoo Animals ◽  
Viruslike Particles ◽  
And Behavior ◽  
Insect Viruses

Economically important insects include pests of plants, animals and stored products as well as insects produced commercially (honey bees, silkworms, insects for fish bait and food for birds and zoo animals). Other insects are produced in large numbers for experimental purposes, biological control of insect pests and weeds and the production of sterile insects for population suppression. Insect viruses may affect morphology, physiology and behavior, often reducing longevity and reproductive potential. Thus insect viruses can be used as biological control agents of pest insects. Insect viruses may also interfere with the production or function of biological control agents (e.g., parasitoids and predators) and insects used for research purposes. Therefore, it is advantageous to screen commercial and research colonies and imported insects for viruses.Electron microscopy of negatively stained specimens (NS EM) offers a relatively rapid and inexpensive means of screening populations of insects for the presence of viruses or viruslike particles and to monitor the progress of virus control programs.

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