Urophora affinis

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Compatibility of seed head biological control agents and mowing for management of spotted knapweed.

Story Jim M; Corn Janelle G; White Linda J Montana Agricultural Experiment Station, Western Agricultural Research

Bibliographic Information

Answer 2:

picloram chlorophenoxyacetate Urophora Centaurea control

Supplementary Terms

(toxicity of, to Urophora affinis and U. quadrifasciata, integrated control of spotted knapweed in relation to)

Role: PRP (Properties)

37339-60-9

1918-02-1, Picloram

94-75-7, 2,4-D, biological studies

(of spotted knapweed, integrated, compatibility of picloram and 2,4-D with Urophora for)

Weed control

(integrated control of, with 2,4-D and picloram and Urophora)

Centaurea maculosa

(in integrated control of spotted knapweed, 2,4-D and picloram compatibility in relation to)

Urophora quadrifasciata

Urophora affinis

Indexing -- Section 5-3 (Agrochemical Bioregulators)

Field studies were conducted to evaluate the acute effects of spring applications of 2,4-D, picloram and a 2,4-D-picloram mixt. on

overwintering larvae of U. affinis and U. quadrifasciata assocd. with spotted knapweed, Centaurea maculosa (Compositae:

Cynareae). Also, the chronic effects of picloram of the re-establishment of the flies into previously treated spotted knapweed

sites were evaluated. Spring applications of 2,4-D, picloram, or their combination did not significantly affect larval-pupal mortality

rates of U. affinis. Picloram and a picloram-2,4-D mixt. did not significantly affect U. quadrifasciata mortality. There were

significant differences, albeit conflicting, between the high and low rates of 2,4-D in the two plots studied. Flies from one plot

exhibited a higher rate of mortality with the high rate of 2,4-D whereas flies from the second plot displayed higher mortality with thelower rate of 2,4-D. No long-term impacts of picloram on the reestablishment of Urophora spp. into previously treated sites were

found. Infestation rates (no. of galls per capitulum and percent capitula infested) for the two fly species in treated plots were not

significantly different from those in control plots. Larval-pupal mortality rates for both species were also not significantly

affected. Thus, applications of 2,4-D and picloram are generally compatible with the utilization of these two biol. control agents for

the management of spotted knapweed in northern Idaho.

Abstract

Compatibility of picloram and 2,4-D with Urophora affinis and U. quadrifasciata (Diptera: Tephritidae) for spottedknapweed control. McCaffrey, Joseph P.; Callihan, Robert H. Dep. Plant, Soil, Entomol. Sci., Univ. Idaho, Moscow, ID,

USA. Environmental Entomology (1988), 17(5), 785-8. CODEN: EVETBX ISSN: 0046-225X. Journal written in English.

CAN 110:2811 AN 1989:2811 CAPLUS (Copyright (C) 2011 ACS on SciFinder (R))


Answer 1:

22 July 2011 Page: 1SciFinder


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Five insect biological control agents that attack flower heads of spotted knapweed, Centaurea stoebe L. subsp.

micranthos (Gugler) Hayek, became established in western Montana between 1973 and 1992. In a controlled field

experiment in 2006, seed-head insects reduced spotted knapweed seed production per seed head by 84.4%. The

seed production at two sites in western Montana where these biological control agents were well established was

91.6-93.8% lower in 2004-2005 than 1974-1975, whereas the number of seed heads per square meter was 70.7%

lower, and the reproductive potential (seeds/m(2)) was 95.9-99.0% lower. The average seed bank in 2005 at four sites

containing robust spotted knapweed populations was 281 seeds/m(2) compared with 19 seeds/m(2) at four sites where

knapweed density has declined. Seed bank densities were much higher at sites in central Montana (4,218

seeds/m(2)), where the insects have been established for a shorter period. Urophora affinis Frauenfeld was the mostabundant species at eight study sites, infesting 66.7% of the seed heads, followed by a 47.3% infestation by Larinus

minutus Gyllenhal and L. obtusus Gyllenhal. From 1974 to 1985, Urophora spp. apparently reduced the number of

seeds per seed head by 34.5-46.9%; the addition of Larinus spp. further reduced seed numbers 84.2-90.5% by 2005.

Path analysis indicated that both Larinus spp. and U. affinis contributed significantly to reduction of seed production

Abstract

Influence of seed head-attacking biological control agents on spotted knapweed reproductive potential inwestern Montana over a 30-year period. Story Jim M; Smith Lincoln; Corn Janelle G; White Linda J Montana

Agricultural Experiment Station, Western Agricultural Research Center, 580 Quast Ln., Corvallis, MT 59828, USA

[email protected] Environmental entomology (2008), 37(2), 510-9. Journal code: 7502320. ISSN:0046-225X.

United States. Journal; Article; (JOURNAL ARTICLE); (RESEARCH SUPPORT, NON-U.S. GOV'T); (RESEARCH

SUPPORT, U.S. GOV'T, NON-P.H.S.) written in English. PubMed ID 18419924 AN 2008259662 MEDLINE

(Copyright (C) 2011 U.S. National Library of Medicine on SciFinder (R))


Answer 3:

*Seeds: PS, parasitology

*Insects: PH, physiology

*Host-Parasite Interactions

*Centaurea: PS, parasitology

Animals

Controlled Terms

Field studies were conducted at two sites in western Montana during 2006 and 2008 to assess the compatibility of

mowing with five seed head insect species introduced for biological control of spotted knapweed, Centaurea stoebe

Lamarck subsp. micranthos. In 2006, mowing of spotted knapweed plants at the bolting and flower bud stages

resulted in the development of new seed heads that contained significantly more seeds and significantly fewer larvae

of each insect species than in seed heads in unmowed controls. No seed heads were produced in the plots mowed at

the flowering stage. Seed numbers per seed head in 2008 were also significantly higher in plots mowed at the bolting

stage than in unmowed controls, but between-treatment differences in insect numbers were more variable. The seed

head insects Larinus spp. and Urophora affinis Frauenfeld were the primary cause of the reduced knapweed seed

numbers per seed head in 2006. Spotted knapweed should not be mowed at the bolting and flower bud stages if large

populations of seed head insects are present because mowing can result in the formation of new seed heads that are

free from the insects' attack, thus allowing greater seed production. Mowing of spotted knapweed at the flowering

stage and later can be conducted without a subsequent increase in seed production, but the mowing may cause

mortality of the insect larvae.

Abstract

Center, Corvallis, MT 59828, USA [email protected] Environmental entomology (2010), 39(1), 164-8. Journal

code: 7502320. E-ISSN:1938-2936. United States. Journal; Article; (JOURNAL ARTICLE); (RESEARCH SUPPORT,

NON-U.S. GOV'T); (RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.) written in English. PubMed ID 20146853

AN 2010098730 MEDLINE (Copyright (C) 2011 U.S. National Library of Medicine on SciFinder (R))



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Time Factors

*Seeds: PS, parasitology

Reproduction: PH, physiology

Population Density

*Pest Control, Biological: MT, methods

Montana

*Insects: PH, physiology

Feeding Behavior: PH, physiology

Conservation of Natural Resources

*Centaurea: PS, parasitologyAnimals

Controlled Terms

over the 30-yr period. Spotted knapweed density may not decrease significantly until the seed bank falls below a

critical threshold.


Urophora affinis

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