1) Project title: Biological control of purple loosestrife (Lythrum salicaria L.) in North Dakota

Investigators: Rodney G. Lym and Katheryn M. Christianson, Dept. of Plant Sciences, North Dakota State University.

Contact: Rodney G. Lym (rod_lym@ndsu.nodak.edu)

Project Description: Purple loosestrife is found in 11 North Dakota counties with the largest infestations in urban areas.  Biological control of purple loosestrife fits well in urban areas considering public apprehension of herbicides sprayed in close proximity to residential areas. An experiment was established in the Chautauqua Park along the Sheyenne River in Valley City, North Dakota where a mixed population of the leaf feeding beetles Galerucella calmariensis (4000) and G. pusilla (10,000) were released at a single release point in June 1998 and 1999, respectively.  Galerucella spp. established at Valley City as both adults and egg masses were found in 1999, 1 yr after release and began to reduce the purple loosestrife infestation 2 yr following release (Table 1).  Stem height was reduced at the release pole from 1.4 m to 0.4 m in 1999 and 2000, respectively.  Also the average flower spike length in 2000 was reduced to zero at the release pole and 25 feet from the pole.  The number of stems increased following the Galerucella spp. release even though the number of flowering plants and stem length decreased.  In general, the plants were short and remained in the vegetative growth stage 2 years after the first biocontrol agent was released. The number of eggs observed increased from an average of 1/m² in 1998 to 27/m² in 2000.  However, there was no increase in the number of larvae observed and only a slight increase in adults.  The reason for the large increase in eggs observed compared to the small increase in adults may be due to the adults moving to purple loosestrife further down stream from the experimental site.  Also, since the area is in a city park, some of the reduction may be due to loss from insecticide spraying conducted for mosquito control. 

2) Project title: Biology and seasonal abundance of parasitoids of the banded sunflower moth (Lepidoptera: Tortricidae) in sunflower. Biol. Control 20: 113-121.

Investigator: Laurence D. Charlet. USDA-ARS, North Crops Science Laboratory, Fargo, ND.

Contact: Laurence D. Charlet (charletl@fargo.ars.usda.gov)

Project description: Mortality, parasitization, and overwintering development through pupation of the banded sunflower moth, Cochylis hospes Walsingham, larvae and two of its endoparasitoids, Glypta prognatha Dasch and Chelonus phaloniae Mason, were followed over a two-year period (1987 to 1989). Development of parasitoids in the field was determined for each species by examination of moth eggs and larvae during the 1989 season. Parasitoids of C. hospes, recovered from cultivated sunflower, Helianthus annuus L., from North and South Dakota, and Minnesota in 1994 and 1995, parasitized 24% and 17% of larvae, respectively. Species of Hymenoptera collected included G. prognatha and Trathala sp. (Ichneumonidae), C. phaloniae and Macrocentrus ancylivorus Rohwer (Braconidae), and Perilampus robertsoni Crawford (Pteromalidae). The most abundant parasitoid was G. prognatha. In 1994 and 1995, C. phaloniae, an egg-larval parasitoid, emerged earlier but was less abundant than the later-occurring larval parasitoid G. prognatha. Species of parasitoids collected from cultivated sunflower and five species of native sunflowers were similar. An additional parasitoid, Mastrus sp. (Ichneumonidae), was recovered only from the native sunflowers H. annuus and H. tuberosus L. Results from 1994 and 1995 showed that parasitization rates for the total season by the two most abundant parasitoids were similar in fields using three planting dates. These results suggest that altering planting date could be successfully used as a pest management strategy without disrupting the biological control of the banded sunflower moth. Conservation of these parasitoids in the sunflower agroecosystem is needed since they play an important role in the management of C. hospes.

3) Project title: The effect of Aphthona czwalinae and A. lacertosa (Coleoptera: Chrysomelidae) larval feeding on leafy spurge, Euphorbia esula L., root systems and stem density in

North Dakota: 1988-96. Submitted to Biological Control.

Investigators:  Donald A. Mundal, Denise L. Olson, and Robert B. Carlson, Dept. of Entomology, North Dakota State University.

Contact: Denise L. Olson (Denise.Olson@ndsu.nodak.edu) 

Project description: Leafy spurge, Euphorbia esula L., is a perennial plant native to Eurasia that has become a widespread weed in North Dakota.  Since 1988, North Dakota State University, Entomology Department, has conducted research on leafy spurge at several locations using Aphthona czwalinae Weise, and A. lacertosa Rosenheim, to determine what impact larval feeding has on the root mass and stem density.  A mixed shipment of Aphthona lacertosa (36%) and A. czwalinae was received from the United States Department of Agriculture-Animal Plant Health Inspection Service (USDA-APHIS) and Agriculture Research Service (ARS) in June of 1988 and released into a single field cage.  By 1993, adult flea beetles, collected for redistribution, were 74% A. lacertosa.  The population of flea beetles consisted of 98% A. lacertosa after 1993.  Aphthona lacertosa established and reduced leafy spurge stem and root tissues 70 to 90% in habitats ranging from high and dry to wet dense wooded areas that have a soil environment of silt loam, clay loam, loam or loam/fine sand loam, with a pH of 6.8-7.9 and 6.0-9.8% organic matter.  A fine sand soil classification appears to restrict the development of filament roots within a few centimeters of the soil surface.  Consequently, an accessible food source is not available for newly emerged A. lacertosa larvae, resulting in reduced impact and population development under these conditions.

4) Project title: The effect of Aphthona flava flea beetle (Coleoptera: Chrysomelidae) larval feeding on leafy spurge, Euphorbia esula L., root systems and stem density in North Dakota:

1986-95. Submitted to Biological Control.

Investigators: Donald A. Mundal, Denise L. Olson, and Robert B. Carlson, Dept. of Entomology, North Dakota State University.

Contact: Denise L. Olson (Denise.Olson@ndsu.nodak.edu) 

Project description: Leafy spurge, Euphorbia esula L., is a perennial plant native to Eurasia that has become a widespread weed in North Dakota.  Starting in 1986, North Dakota State University, Entomology Department, conducted research on leafy spurge at several locations using the flea beetle specie Aphthona flava Guillebeau, to determine what impact larval feeding has on leafy spurge root mass and stem density.  Aphthona flava obtained from the United States Department of Agriculture-Agriculture Research Service (USDA-ARS) and Animal Plant Health Inspection Service (APHIS) were released at different locations in North Dakota.  Aphthona flava  reduced the root mass and stem densities by 40 to 60% within five years in study areas where a population level of 85-100 adults per m² was constant.  Populations of A. flava only persisted at these levels in habitats that consisted of silt clay loam soil with a pH of 7.6-7.9 and 7.3-8.4% organic matter the year beetles were released.  Stem density and height ranged from 127-329 stems per m² and 35.56-45.72 cm.  The habitats that are not conducive for A. flava survival and development consisted of loam, find sand loam, or clay loam soil, with a pH of 6.6-7.9 and 2.8-8.0% organic matter.  Stem density and height ranged from 145-371 stems per m² and 48.26-60.96 cm.  Because the habitat requirement for A. flava is restricted, it will be necessary to collect and redistribute this flea beetle into its preferred habitat when using this biological control agent to treat large infestations of leafy spurge that includes a range of habitat characteristics.    

5) Project title: The effect of Aphthona nigriscutis flea beetle (Coleoptera: Chrysomelidae) larval feeding on leafy spurge, Euphorbia esula L., root systems and stem density in

North Dakota: 1989-96. Submitted to Biological Control.

Investigators: Donald A. Mundal, Denise L. Olson, and Robert B. Carlson, Dept. of Entomology, North Dakota State University.

Contact: Denise L. Olson (Denise.Olson@ndsu.nodak.edu) 

Project description: Leafy spurge, Euphorbia esula L., is a perennial plant native to Eurasia that has become a widespread weed in North Dakota.  Starting in 1989, North Dakota State University, Entomology Department, conducted research on leafy spurge at several locations using Aphthona nigriscutis Foudras, to determine what impact larval feeding has on the root mass and stem density.   Aphthona nigriscutis flea beetles received from United States Department of Agriculture-Agriculture Research Service (USDA-ARS) and Animal Plant Health Inspection Service (APHIS) were released in various habitats throughout North Dakota.  The success of A. nigriscutis will vary among characteristically different habitats that often occur in very large infestations of leafy spurge.  Aphthona  nigriscutis is more successful when leafy spurge is growing under 90% direct sunlight in a well drained loam soil with a pH of 7.1 to 7.9 and 8 to 11% organic matter; and, the spurge stem height and density is less than 45.72 cm and 187 stems m².  Aphthona nigriscutis can reduce a spurge infestation by 90% under these conditions.  This flea beetle species will reduce the vegetative tissues of leafy spurge by 50 to 70% when the habitat consist of a loam or loam find sand soil with a ph of 6.5-7 and 2.4-4.3% organic matter; and, the stem density is 119 to 229 stems per m² with a plant height of 30.48 to53.34 cm.  Aphthona nigriscutis does not reach sufficient population levels to impact leafy spurge infestations in habitats where the soil is classified fine sand with 0.9 to 2% organic matter.

6) Project Title The utilization of Oberea erythrocephala as an additional bio-control agent on leafy spurge in the little Missouri River basin and in southeast and north central North Dakota.

Investigators: Denise L. Olson and Donald A. Mundal, Dept. of Entomology, North Dakota State University.

Contact: Denise L. Olson (Denise.Olson@ndsu.nodak.edu) 

Project description: Leafy spurge inhabits a wide range of different environmental habitats.  Leafy spurge placement in the soil appears to limit the success of Aphthona spp. to only a particular range of environmental conditions.  The beneficial cerambycid beetle, Oberea erythrocephala has a different reproductive and feeding behavior and therefore, may be better suited for successful establishment in environmental habitats where the success of Aphthona flea beetles has been less than satisfactory.  The successful establishment of Oberea will support the efforts of managing leafy spurge with another bio-control agent. Oberea erythrocephala was released at four sites in the little Missouri River basin, and five sites in southeast and one site in north central North Dakota.   Each site was examined for the presence of Oberea population development and activity (stem girdling and oviposition punctures).  At all the sites (not including north central North Dakota) Oberea was present the following year after release.  An average of 3.7 adults per sweep and 8.5 adults were collected two and three years after release in southeast North Dakota.  An average of 5.7% and 4.9% of the spurge plants were damaged by Oberea among the release sites in the Little Missouri River basin during the initial release year and one year following release.  Leafy spurge stand counts were reduced an average of 4.22 stems/m² at two of these locations and increased by 4.6 stems/m² at one location.  This study indicates that O. erythrocephala will establish under different environmental conditions that vary in annual temperature and precipitation , soil composition, and landscape.       

7) Project title: Effects of alkaloids on the growth of Beauveria bassiana.

Investigators: Carl L. Jorgensen and Denise L. Olson, Dept. of Entomology, North Dakota State University.

Contact: Denise L. Olson (Denise.Olson@ndsu.nodak.edu) 

Project description: The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), has developed resistance to most classes of insecticides after a history of frequent insecticide applications.  Resistant potatoes and the entomopathogen, Beauveria bassiana (Balsamo) Vuillemin, are effective against CPB.  The integration of compatible tactics in an IPM program will be necessary for sustainable management of this pest.  The compatibility of B. bassiana with alkaloids was determined in laboratory studies.  Chaconine, solanine, tomatine, leptin I, leptin II, a  crude extract from a resistant potato genotype (ND4832-17), water, and ethanol were tested at 0.0016, 0.0033, 0.0065, and 0.013 mg/cm²; chaconine, solanidine, demissidine, solasodine, dolanine, tomatine, tomatidine, water, and ethanol were tested at 0.0065, 0.013, and 0.026 mg/cm² against B. bassiana.  In the first series of alkaloids, the fungal colony area was measured at 67, 91, 115, and 139 hours; colony numbers were counted at 67 hours after inoculation.  In the second series of alkaloids, the colony diameter and numbers were measured at 48, 72, and 96 hours after inoculation.  None of the treatments in the first series affected the growth of B. bassiana.  None of the alkaloids, at any rate, had an effect on the number of colonies formed.  In the second series of alkaloids, tomatidine, inhibited colony growth the most at all rates and times.  The other alkaloids only slightly inhibited the growth of B. bassiana compared to the checks.  Data from this series indicated that B. bassiana would be compatible with insect-resistant potatoes in an IPM program.  

8) Project title: Evaluation of biologically based integrated pest management for Colorado potato beetle (Leptinotarsa decemlineata).

Investigators: Carl L. Jorgensen and Denise L. Olson, Dept. of Entomology, North Dakota State University.

Contact: Denise L. Olson (Denise.Olson@ndsu.nodak.edu) 

Project description: The Colorado potato beetle (CPB), Leptinotarsa decemlineata, is a serious foliage pest of potatoes.  Insecticide resistance has made chemical insecticide control unreliable in some circumstances.  The compatibility of alternative control tactics is essential for developing integrated pest management for CPB.  In 1999 and 2000, a cage study was conducted to evaluate the interactions of a resistant potato genotype or a susceptible potato type; the CPB predator, Perillus bioculatus; and chemical and biological insecticides.  Colorado potato beetle population levels and percent defoliation were recorded twice a week throughout the production season.  Tuber weight was recorded for yield data.  Both years, some difference were detected between the Russet Burbank variety and the resistant genotype, but the differences may be due to other factors besides inherent characteristics between the potato types.  In 1999, storms damaged the resistant plants, and they were not able to recover from the events and CPB feeding, resulting in differences in yield and defoliation.  In 2000, the resistant potato type reduced the adult population and the defoliation associated with the adult population.  The plots with P. bioculatus had a greater reduction of CPB compared to plots without P. bioculatus,  but plant injury and subsequent yield losses did occur.  The biological insecticides, B. bassiana and B. thuringiensis, performed as well (in 2000) or better (in 1999) than Furadan in reducing CPB populations.  Interactions of the predator, and chemical or biological insecticides had the most notable effect on CPB populations and their effects on defoliation, but did not affect differences in yield. 

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