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

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.

Weed Science ◽  
1987 ◽  
Vol 35 (2) ◽  
pp. 145-148 ◽  
Author(s):  
Jim M. Story ◽  
Robert M. Nowierski ◽  
Keith W. Boggs

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.


2020 ◽  
Vol 49 (4) ◽  
pp. 823-828
Author(s):  
Alex N Neidermeier ◽  
Darrell W Ross ◽  
Nathan P Havill ◽  
Kimberly F Wallin

Abstract Two species of silver fly, Leucopis argenticollis (Zetterstedt) and Leucopis piniperda (Malloch) (Diptera: Chamaemyiidae), from the Pacific Northwest region of North America have been identified as potential biological control agents of hemlock woolly adelgid (Hemiptera: Adelgidae: Adelges tsugae Annand) in eastern North America. The two predators are collectively synchronized with A. tsugae development. To determine whether adult emergence of the two species of silver fly are also synchronized with one another, we collected adult Leucopis which emerged from A. tsugae-infested western hemlock [Pinaceae: Tsuga heterophylla (Raf.) Sarg.] from four sites in the Pacific Northwest over a 29-d period. Specimens were collected twice daily in the laboratory and identified to species using DNA barcoding. The study found that more adult Leucopis were collected in the evening than the morning. Additionally, the daily emergences of adults over the 29-d sampling period exhibited sinusoidal-like fluctuations of peak abundance of each species, lending evidence to a pattern of temporal partitioning. This pattern could have logistical implications for their use as biological control agents in eastern North America, namely the need to release both species for maximum efficacy in decreasing A. tsugae populations.


Weed Science ◽  
2004 ◽  
Vol 52 (1) ◽  
pp. 172-177 ◽  
Author(s):  
E. R. Lutgen ◽  
M. C. Rillig

Spotted knapweed is an invasive mycorrhizal weed prevalent in the Pacific Northwest of the United States. Little is known about the effects of spotted knapweed or its management methods on soil quality and soil structure. This study compared soils from spotted knapweed–infested areas with areas where spotted knapweed is being managed using several herbicides and mechanical treatments. We measured concentrations of glomalin, a glycoprotein produced by arbuscular mycorrhizal fungi (AMF), that is correlated with soil aggregate stability, AMF hyphal length, and percent water-stable aggregates (WSA) in soils from managed and unmanaged areas. Areas with high knapweed density (unmanaged areas) generally had lower glomalin concentrations and AMF hyphal lengths compared with areas receiving chemical and combined mechanical–chemical management treatments. Total glomalin was significantly negatively correlated with percent knapweed cover. However, WSA was high (70 to 80%) in soils from all management treatments and was not affected by knapweed cover. Our results suggest that spotted knapweed does not have negative effects on soil quality from our study site, likely because of the high aggregate stability of the soils in the area. However, Centaurea maculosa may have negative effects on soil quality in soils with lower aggregate stability.


1985 ◽  
Vol 117 (8) ◽  
pp. 1061-1062 ◽  
Author(s):  
Jim M. Story

Two tephritid flies of European origin have been introduced into North America for biological control of spotted knapweed, Centaurea maculosa Lam., and diffuse knapweed, C. diffusa Lam. One, Urophora affinis Frauenfeld, was released in British Columbia in 1970 and in 5 states, including Montana, in 1973 (Hanis 1980a; Maddox 1979; Story and Anderson 1978). The other, Urophora quadrifasciata (Meigen), was introduced at Ned's Creek, British Columbia but was not released in the United States. The larvae of both flies induce galls (1 larva/gall) in immature knapweed flower heads and thus reduce seed production. Galls of Urophora affinis occur in the flower-head receptacle whereas galls of U. quadrifasciata are in the ovary wall. In contrast with U. affinis, which has only a partial second generation, U. quadrifasciata normally has 2 complete generations per year, induces thinner galls, and attacks more-mature flower heads than does U. affinis (Harris 1980a).


1997 ◽  
Vol 129 (2) ◽  
pp. 373-374 ◽  
Author(s):  
J.M. Story ◽  
W.R. Good ◽  
L.J. White

Cyphocleonus achates (Fahaeus) is a Eurasian, root-feeding weevil introduced into North America for the biological control of spotted knapweed, Centaurea maculosa Lamarck. Stinson et al. (1994) reported that C. achates is one of the most damaging root-feeding insects on knapweed in Eurasia and should be a valuable addition to the biocontrol effort in North America. The biology, host specificity, and potential impact of the weevil were described by Stinson et al. (1994). Larvae mine into the root cortex where they induce formation of a conspicuous root gall. Feeding by older larvae causes much damage, especially to small plants or plants containing several larvae. The weevil overwinters as a larva in the root and emerges as an adult from mid-July to October. Adult weevils are large (14 mm long) and flightless, and feed on knapweed foliage. The weevil has one generation per year.


Plant Disease ◽  
1997 ◽  
Vol 81 (1) ◽  
pp. 113-113
Author(s):  
S. A. Kearing ◽  
R. M. Nowierski ◽  
W. E. Grey

In June and July of 1995, stems of spotted knapweed (Centaurea maculosa) displayed dieback at two field locations near Bozeman, MT. Dieback developed after plant bolting and during apical bud development. Seedlings and plants in the rosette stage were not affected. Symptoms included curling of stems at the tip, similar to a shepherd's crook, and brown, discolored stem tissues separated from healthy tissues by a constriction. Dissection of the stem showed disintegrated pith and blackened, infected vascular bundles. The disease was observed after a 3-week period of cool (0.5°C below normal of 15°C, 2 nights below 0°C) and wet (nine rainfall periods totaling 7.1 cm) weather and extensive bud wounding by the seed head fly, Urophora affinis Frnfd., an introduced biological control agent on spotted knapweed. Fluorescent pseudo-monads were isolated from six symptomatic stems by culturing the homogenate from surface-sterilized, macerated, symptomatic sections on King's medium B (KB) (1). A representative purified strain induced a hypersensitive reaction on tobacco (Nicotiana tabacum ‘White Burley’) leaves. The strain was identified as Pseudomonas syringae pv. syringae by GC-FAME analysis (TSBA [rev. 3.90]) with similarity index of 0.945; and as Pseudomonas syringae pv. aptata by Biolog (version 3.7) with similarity index of 0.840 by Microbe Inotech Laboratories, Inc. St. Louis, MO. New stems on five spotted knapweed plants were spray inoculated with bacteria from 48-h KB cultures suspended in 0.2% Silwet L-77 to a concentration of 1010 CFU per ml. Five plants were misted with 0.2% Silwet L-77 in sterile water as a check. All plants were placed in a humidity chamber for 48 h, then transferred to a greenhouse. After 30 days at 20 ± 3°C, approximately 30% relative humidity, and a photoperiod of 14 h, no symptoms were observed on inoculated or control plants. Pathogenicity was demonstrated by injecting each of 10 healthy, developing spotted knapweed buds with 0.1 ml of the strain suspended in sterile water at 107 CFU/ml. Inoculated plants and controls, injected with sterile water only, were placed in a humidity chamber for 48 h, then in greenhouse conditions as before. After 14 days, only inoculated plants developed stem necrosis and dieback. Fluorescent pseudomonads were isolated from affected stem tissue 3 to 5 cm below the point of inoculation. The original strain and the strain from inoculated plants were identified as Pseudomonas syringae pv. syringae (GC-Fame analysis (TSBA [rev. 3.90]) with similarity indices of 0.941 and 0.938, respectively) by Ann Kennedy, USDA-ARS-LWMC, Pullman, WA. In the field, diseased plants had a sporadic distribution, but were more frequent in areas of high soil moisture. The combination of cold and wet conditions, coupled with bud wounds created by the seed head fly U. affinis, may be environmental requirements for spotted knapweed stem dieback caused by P. syringae in the field. This is the first report of a bacterial disease of spotted knapweed. Reference: (1) E. O. King et al. J. Lab. Clin. Med. 44:301, 1954.


2000 ◽  
Vol 18 (4) ◽  
pp. 197-201 ◽  
Author(s):  
P.D. Pratt ◽  
B.A. Croft

Abstract The predatory mite Neoseiulus fallacis (Garman) is an important biological control agent of spider mites in landscape plants produced in the Pacific Northwest. Using pesticide toxicity information from the SELCTV database and recent literature reports, we estimated toxicity of several general pesticide classes to N. fallacis, compared susceptibility of N. fallacis to 3 other predatory mites and developed summary tables of pesticide toxicity to N. fallacis. Pesticide classes ranged from low or non-toxic to N. fallacis (i.e., organosulfur) to highly toxic (i.e., oxime carbamate). Pesticide susceptibility data for N. fallacis within or between chemical classes was similar to data for either of Typhlodromus pyri Scheuten, Galendromus occidentalis Nesbitt, or Phytoseiulus persimilis Athias-Henriot. While all pesticide types (i.e., insecticides, fungicides, herbicides, etc.) contained representatives that were highly toxic to N. fallacis, various compounds were rated low or non-toxic. On average, insecticides were most toxic to N. fallacis, fungicides least toxic and herbicides intermediate. Probability of exposure and integration of N. fallacis into current control practices are discussed.


2019 ◽  
Vol 110 (3) ◽  
pp. 303-308 ◽  
Author(s):  
Alexander Rose ◽  
Darrell W. Ross ◽  
Nathan P. Havill ◽  
Kyle Motley ◽  
Kimberly F. Wallin

AbstractThe hemlock woolly adelgid (Hemiptera: Adelgidae: Adelges tsugae Annand) is an invasive insect, introduced from Japan to eastern North America, where it causes decline and death of hemlock trees. There is a closely related lineage of A. tsugae native to western North America. To inform classical biological control of A. tsugae in the eastern USA, the density and phenology of three native western adelgid specialist predators, Leucopis argenticollis (Zetterstedt), Le. piniperda (Malloch) (Diptera: Chamaemyiidae), and Laricobius nigrinus Fender (Coleoptera: Derodontidae), were quantified in the Pacific Northwest. Infested branches were collected from western hemlock (Pinaceae: Tsuga heterophylla (Raf.) Sarg.) at four sites around the Puget Sound, Washington and three sites in Oregon. Immature Leucopis were identified to species using DNA barcodes. Leucopis argenticollis was roughly twice as abundant as Le. piniperda. Laricobius nigrinus larvae were more abundant than the two species of Leucopis during the egg stage of the first adelgid generation, but Leucopis were present as feeding larvae during the second adelgid generation when La. nigrinus was aestivating in the soil, resulting in Leucopis being more abundant than La. nigrinus across the entire sampling period. Adelges tsugae and La. nigrinus densities were not correlated, while A. tsugae and Leucopis spp. densities were positively correlated. Leucopis spp. and La. nigrinus densities were negatively correlated. These results support the complementary use of La. nigrinus and the two Leucopis species for biological control of A. tsugae in the eastern USA, and point to the need for further investigation of spatial and temporal niche partitioning among the three predator species.


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