1) Project Title: The efficacy of ecorational versus chemical insecticides against the crucifer flea beetle, Phyllotreta cruciferae (Coleoptera: Chrysomelidae), on canola.

Investigators: Frank Antwi, Denise Olson, and Janet Knodel

Contact: Denise Olson, North Dakota State University, Dept. of Entomology, Hultz Hall, 1300 Albrecht Blvd., Fargo, ND 58105, Ph: 701.231.6292, FAX: 701.231.8557
e-mail: Denise.Olson@ndsu.edu

Project Description: The crucifer flea beetle, Phyllotreta cruciferae (Goeze) is a key economic pest of canola on Northern Great Plains of the United States and Canada. Adult flea beetles emerge from over wintering sites early in the spring as the air temperature warms up to approximately 15 C. The beetles quickly move into canola fields and immediately begin to feed on young cotyledons and leaves, and can reduce newly emerged plant stands within a few days. Feeding at the cotyledon stage of the crop by adults accounts for the greatest crop loss to this pest.

Insecticide seed treatments or foliar sprays are the first line of defense against P. cruciferae at the adult stage, when canola is in the seedling stage, The potential the crucifer flea beetle to develop resistance to synthetic insecticides coupled with the focus in agriculture for more environmentally friendly pest management drives the need for ecorational insecticide alternatives for P. crucifer management in canola.

In a leaf dip bioassay the ecorational insecticides SpinTor® 2 SC (spinosad), BotaniGard® ES (Beauveria bassiana), Surround® WP (kaolin, a clay), and Neemix® 4.5 EC (azadirachtin) were compared to two chemical insecticides, a foliar spray Capture® 2 EC (bifenthrin) and a seed treatment Helix® XTra (thiamethoxam), for their lethal concentration and lethal time against the adult crucifer flea beetle. LT25, LT50, LT75, and pairwise comparison test for the insecticide concentration groupings (0, 1X-1.5X and 2X-4X) was estimated for each treatment using survival functions. Flea beetle mortality increased in response to increasing concentrations especially for Helix XTra, Capture, and SpinTor. The LT50 values of the insecticides tested showed their efficacy to be in the order of Helix XTra, Capture, and SpinTor > BotaniGard, Neemix, and Surround. Helix XTra, Capture and SpinTor showed the best efficacy after 48 hours of exposure. SpinTor reduced the flea beetle population by at least 50% within 48 hours. Among the ecorational insecticides tested, SpinTor may be a suitable alternative to synthetic insecticides in canola production.

2) Project title: Field evaluations of ecorational versus synthetic chemical insecticides for crucifer flea beetle, Phyllotreta cruciferae (Coleoptera: Chrysomelidae) management in canola.

Investigator: Frank Antwi, Denise Olson, and Janet Knodel

Contact: North Dakota State University, Dept. of Entomology, Hultz Hall, 1300 Albrecht Blvd., Fargo, ND 58105, Ph: 701.231.6292, FAX: 701.231.8557
e-mail: Denise.Olson@ndsu.edu

Project description: Field studies were conducted to evaluate the effect of the ecorational insecticides SpinTor® , BotaniGard®, Neemx®, and Surround® against the crucifer flea beetle at the cotyledon stage of canola. These ecorational insecticides were compared to the foliar synthetic insecticide Capture (bifenthrin) and the synthetic seed treatment Helix XTra®. At 14 days after foliar treatment, flea beetle feeding injury was significantly less in the synthetic insecticide treatments compared to the ecorational insecticides. Among the ecorational insecticides, SpinTor had the best efficacy against P. cruciferae. Helix XTra, Capture, and SpinTor resulted in higher yields compared to the other treatments, and the yields between the SpinTor and Capture were not significantly different.

3) Project title: The effect of winter soil temperatures on Aphthona over wintering survival and leafy spurge growth pattern.

Investigators: Ankush Joshi and Denise Olson

Contact: Denise Olson, North Dakota State University, Dept. of Entomology, Hultz Hall, 1300 Albrecht Blvd., Fargo, ND 58105, Ph: 701.231.6292, FAX: 701.231.8557
e-mail: Denise.Olson@ndsu.edu

Project Description: Aphthona flea beetle spp. were introduced into North America during the mid-1980’s as biological control agents of leafy spurge and since have had a significant impact on spurge in numerous areas throughout the Northern Great Plains States. However the Aphthona spp. have not established at all release sites or adequately controlled leafy spurge at all sites where they have established. Field observations in North Dakota indicate that Aphthona species fail to over winter in some locations. Aphthona spp. are univoltine and require 2-3 months of low temperature (4-10oC) during the larval stage to complete the life cycle. Skinner et al. (2004) reports that a 60 d period at 3oC may be sufficient for the flea beetle to complete their development. Under field conditions in the Northern Great Plains states winter soil temperatures can reach below the lower threshold temperature for Aphthona spp. and can last for substantially longer than 60 d (Skinner et al. 2004, Sommer and Maw 1982).

We evaluated the impact of environmental conditions such as ground cover, winter soil temperature and the duration of the winter soil temperature on the over wintering success of Aphthona flea beetles in a range pasture infested with leafy spurge and with an established population of the Aphthona flea beetles spp., predominantly A. lacertosa (>95%).

During all study years, Aphthona flea beetle spring emergence was lower than the population entering the over wintering phase. During the first year of the study, flea beetle emergence was higher from snow covered plots compared to no-snow plots. Mean winter soil temperature (WST) and mean continuous subfreezing soil temperature (CSFST) were significantly lower, and the total number of winter days (WD) and continuous subfreezing winter days (CSFWD) were significantly higher in the no-snow treatment plots. There was a significant positive linear relationship of spring flea beetle emergence as a function of mean WST, and mean CSFST. The lower mean WST and mean CSFST survival threshold estimate for over wintering flea beetle larvae were -5, and -5.6 oC, respectively. Post winter emergence of flea beetle as a function of WD and CSFWD shows a significant negative linear relationship. Total WD alone explained 80% variation in spring flea beetle emergence. The greater WD and CSFWD survival threshold estimate for over wintering flea beetle larvae were 132.2, and 117.5, respectively. During the second year, spring emergence of the flea beetles was significantly greater from no-snow plots compared to snow covered plots. Mean WST and CSFST, and total WD and CSFWD, were not significantly different between the treatments. In the third year, spring flea beetle emergence was not significantly different among the winter ground treatments. Mean WST and CSFT were significantly higher in soil that had a combination of snow and debris cover compared to in soil with no or only debris covering during the winter months In the fourth years, spring flea beetle emergence were not significantly different among the experimental treatments. Mean WST was significantly lower in those plots with no protection compared to the treatments with snow cover, but not when compared to the debris only winter ground cover. The mean CSFST was significantly lower in the treatment of no winter ground cover compared to the treatments with a ground cover.

4) Project Title: An IPM approach to sustainable management of leafy spurge (Euphorbia esula L.)

Investigators: Ankush Joshi and Denise Olson

Contact: Denise Olson, North Dakota State University, Dept. of Entomology, Hultz Hall, 1300 Albrecht Blvd., Fargo, ND 58105, Ph: 701.231.6292, FAX: 701.231.8557
e-mail: Denise.Olson@ndsu.edu

Project Description: Leafy spurge is an exotic weed in North America and is found primarily in untilled non-cropland habitats such as pastures, rangeland, woodland, roadsides and wastes areas, in addition to on abandoned cropland. This invasive weed can be controlled when herbicides are applied on an annual basses; but, control will decline after discontinuing the herbicide applications. Other control methods including cultivation, competitive grass species, grazing with sheep or goats, or biological control have varying degrees of success against leafy spurge, no one-control tactic appears to be the solution to managing leafy spurge. An integrated pest management (IPM) approach may be more suitable across the diverse habitats in which this weed can flourish. Herbicides have been successfully combined with other management tools, including competitive grass species and biological control agents. In field studies we evaluated the effect of herbicide plus competitive grass species on Aphthona population establishment and development, and we evaluated an IPM approach that combines Aphthona flea beetles with herbicide and competitive grass species as a long-term management strategy for leafy spurge.

Sweep sampling conducted before Aphthona flea beetle releases yielded no beetles at both study sites. The combined effects of herbicide and native grass species had a positive impact on Aphthona spp. establishment and development. The beetles increased to 3.0 and 1.1 per five sweep sample within 4 to 3 years after there initial release. The combined effects Aphthona spp. plus herbicide and native grass species had a significant impact on the leafy spurge, with reductions of 14.3 and 4.7 stems/0.5 m2 over a four and three year period.

5) Project Title: Post establishment habitat occurrence of Aphthona spp.

Investigators: Ankush Joshi and Denise Olson

Contact: Denise Olson, North Dakota State University, Dept. of Entomology, Hultz Hall, 1300 Albrecht Blvd., Fargo, ND 58105, Ph: 701.231.6292, FAX: 701.231.8557
e-mail: Denise.Olson@ndsu.edu

Project Description: Six Aphthona spp. were released in to North Dakota in 1980s as biological control agents of leafy spurge. Four of these introduced flea beetle species are established, and have had verying degrees of suppress on spurge in the region. Aphthona flava was released in 1986 and established in the region, although its population increase has been slow. Aphthona nigriscutis was released in 1989 and was originally the most successful Aphthona spp. in the region. Within five years of releasing 80 beetles of a mixed population of A. czwalinae and A. lacertosa into North Dakota, the beetles expand quickly and the leafy spurge decreased 40 fold from 218 to 5 stems/m2. Two sites in southeast North Dakota provide an excellent opportunity to evaluate long term biological control of the leafy spurge and the population dynamics of the Aphthona flea beetles.

Twelve years after the initial release of Aphthona spp. at the two sites, we evaluated the beetle populations and leafy spurge infestations across different habitat, including: high prairie, mid prairie, thickets, trees, and wetland (combination of low prairie, meadow, and marsh). At one site the flea beetle populations and leafy spurge stands were lower in the thicket, tree and meadow habits with no significant differences in the number of beetles and the amount of spurge between these three habitats. At the second study site the leafy spurge stem count was significantly lower in the mid prairie compared to the other habits. The flea beetle population was very low and not significantly different among the different habitats at this second site.

6) Project Title: Tritrophic effects of soybean variety on natural enemies of the soybean aphid, Glycines max.

Investigators: Derek Crompton, Anne Mueller, and Paul Ode

Contact: Paul Ode, 270 Hultz Hall, 1300 Albrecht Blvd., North Dakota State University, Fargo, ND 58105, Ph: 701.231.5934, FAX: 701.231.8557, e-mail: paul.ode@ndsu.edu

Project Description: Current work is examining the effects of five resistant soybean varieties (Jackson, Palmetto, Sato, 71506, 54610) and four susceptible varieties (Glenwood, Monroe, Arksoy, Ralsoy) is being conducted to see if the parasitoid, Aphelinus albipodes, fitness and performance is affected by aphids reared on these various plants. Similar experiments have been initiated to examine varietal effects on Lysiphlebus tesatceipes and the Multi-colored Asian lady beetle, Harmonia axyridis. Parameters measured include percent parasitism, percent emergence, and body size of the parasitoids and predators feeding on soybean aphids reared on each of the nine varieties. Work is continuing using electronic penetration graph (EPG) to determine whether feeding preference/behavior of soybean aphids is differentially affected by resistant and susceptible soybean varieties. We are particularly interested in whether feeding behavior by parasitized aphids is significantly different than unparasitized aphids. We are extending this work to examine aphid feeding behavior on buckthorn.

7) Project Title: Native sunflowers in the southwest U.S. as sources for natural enemies and resistance of the sunflower stem weevil, a major pest of cultivated sunflower.

Investigators: Larry Charlet, Gerald Seiler, and Paul Ode

Contact: Larry Charlet, USDA-ARS, Northern Crop Science Laboratory, P.O. Box 5677, 1307 18th Street North, Fargo, ND 58105, Ph: (701) 239-1313, FAX: (701) 239-1346
e-mail: charletl@fargo.ars.usda.gov

Project Description: Sunflowers, Helianthus spp., are native to North America and thus the associated insects have coevolved with the plants for centuries. This relationship may have resulted in sunflower populations with mechanisms to reduce feeding injury or to resist insect attack. Also, pests developing in native sunflowers are attacked by different natural enemies. Although pest species have moved into cultivated sunflower, it is possible that some parasite species have not made the transition. Identification of the parasite complex of the sunflower insect pests in native sunflower will determine if there are species which are not present in cultivated sunflower. The potential exits to introduce species from one location to another to increase the diversity of natural enemies and possibly the level of control. The sunflower stem weevil is an important pest of cultivated sunflower, especially in the central Plains production region. The goal of this project was to conduct a survey of the native sunflower species, Helianthus annuus L., in southern Colorado, New Mexico, and Arizona, the location where sunflower originated. We drove over 2400 miles from October 2 through 9, 2005, collecting stalks harboring sunflower stem weevil to identify species of parasitoids attacking the larvae and determine whether or not they are currently present in cultivated sunflower. An additional objective will be to compare numbers of weevil larvae in stalks to locate Helianthus populations with lower insect densities as sources of germplasm that could potentially provide genes for resistance to attack or damage from this sunflower insect pest. Stalks are currently being held in a cold room to break diapause of the weevils. After a period of chilling the stalks will be split, the weevils extracted, and reared for emergence of weevil adults or parasitoids.

8) Project Title: Biological control of purple loosestrife in North Dakota.

Investigators: Rodney G. Lym and Katheryn M. Christianson.

Contact: Rodney G. Lym, Department of Plant Sciences, North Dakota State University, Fargo, ND 58105, Ph: 701.231.8996, FAX: 701.231.8474, e-mail: rod.lym@ndsu.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 about herbicides sprayed in close proximity to residential areas. Three species of purple loosestrife biological control agents were introduced in North Dakota in 1997 and 1998. The biological control agents included two leaf beetles, Galerucella calmariensis and G. pusilla, released in Grand Forks and Valley City, ND, and Hylobius transversevittatus, a root feeding weevil, in Grand Forks. The objective of this research was to evaluate purple loosestrife control with Galerucella spp. along rivers in two urban areas.

The first experiment was established in Chautauqua Park along the Sheyenne River in Valley City, North Dakota. A mixed population of about 4000 Galerucella calmariensis and 10,000 G. pusilla were released at a single point in June 1998 and 1999, respectively. The number of Galerucella spp. adults and egg masses, as well as purple loosestrife stems, stem height, and spike length were recorded at the release point and at 25 foot increments both up and down stream from the release point. In a 1-m2 area, measurements included the number of eggs, larvae, and adults estimated by counting for 60 seconds, height of the five tallest stems, length of the five longest flower spikes, and the total number of stems.

Galerucella spp. established the first year after release as both adults and egg masses were found in 1999 and the population steadily increased through 2002 (Tables 1 and 2). Gallerucella spp. began to decrease the loosestrife stem height and flower spike length 2 yr after release (2000). For instance, stem height was reduced at the release pole from 1.4 m in 1999 to 0.4 m in 2000. Stem height in 2001 was similar to that measured in 2000. The average flower spike length was reduced to zero at the release pole and 25 feet from the pole by 2000, 2 yr after release, and at 50 feet by 2001. Initially, the number of stems increased 2 yr following the Galerucella spp. release from an average of 20 to 43/m2 in 1998 to 2000, respectively. Thereafter, the number of stems declined regardless of the distance from the release point and averaged 2 stems/m2 or less in 2003.

The number of eggs observed increased from an average of 1/m2 in 1998 to 27/m2 in 2000, while larvae began to increase in 2001 and averaged 46/m2 in 2001 (Table 2). The largest number of eggs, larvae, and adults were usually found near the original release pole and decreased as the distance from the release pole increased even 3 yr after release. By 2001 and 2002 adults and evidence of larvae feeding were observed well away from the experiment which indicated the Galerucella spp. were moving out of the research location as the insect population increased and the lythrum population decreased.

The second study was established in a purple loosestrife infestation along a city storm drain in Fargo, ND. The experiment was designed as previously described except the distance measured from the release pole was increased to 100 feet in 25 foot increments. Approximately 10,000 Galerucella spp. were released in June 2002. As in the previous study the lythrum stem density increased initially following release (Table 3.) and Galerucella had established as egg masses and larvae were observed at and 25 feet from the release pole (Table 4).

In this study, Galerucella spp. established and began to reduce the purple loosestrife infestation 2 yr following release. Biological control of purple loosestrife can be an alternative to chemical control in urban areas as long as insecticides sprayed for mosquito control are restricted from the release area.

Brewer, G. J. and L. D. Charlet. 2004. Sunflower beetle (Coleoptera: Chrysomelidae): pattern of larval distribution and parasitism in cultivated sunflower fields. J. Kansas Entomol. Soc. 77: 21-25.

Charlet, L. D. and G. J. Brewer. 2004. Sunflower insect pest management, In E. B. Radcliffe and W. D. Hutchison [eds.], Radcliffe=s IPM World Textbook, URL: http://ipmworld.umn.edu. University of Minnesota, St. Paul, MN http://www.ipmworld.umn.edu/chapters/charlet2.htm

Charlet, L. D., P. Ode, and G. J. Seiler. 2005. Native sunflower in the central and northern Plains as sources for resistance and natural enemies of insect pests of cultivated sunflower: banded sunflower moth and sunflower stem weevil. Proc. 27th Sunflower Research Workshop, Natl. Sunflower Assoc., Fargo, ND, 12-13 January 2005. http://www.sunflowernsa.com/research/research-workshop/documents/ Charlet_NativeSunflowers_05.PDF

Charlet, L. D. and R. M. Aiken. 2005. Impact of planting date on sunflower stem weevil (Coleoptera: Curculionidae) larval density and parasitism in oilseed and confection sunflower in the western Kansas. Crop Management. http://www.plantmanagementnetwork.org/cm/

Erickson, A. M. and R. G. Lym. 2004. Integration of Aphthona spp. flea beetles and herbicides for leafy spurge (Euphorbia esula) control in habitat of the western prairie fringed orchid (Platanthera praeclara). Proc. XI Intern. Symp. Bio. Cont. Weeds (eds Cullen, J. M., Briese, D. T., Kriticos, D. J., Lonsdale, W. M., Morin, L. and Scott, J. k.), pp. 389- 393. CISRO Entom., Canberra, Australia.

Lym, R. G. and R. Becker. 2004. Herbicide use during Aphthona lacertosa flea beetle establishment expedites control of leafy spurge. Proc. XI Intern. Symp. Bio. Cont. Weeds (eds Cullen, J. M., Briese, D. T., Kriticos, D. J., Lonsdale, W. M., Morin, L. and Scott, J. k.), p. 476. CISRO Entom., Canberra, Australia.

Hardy, I.C.W., P.J. Ode and M. Siva-Jothy. 2005. Mating behaviour. Pages 219-260 In: M. Jervis (Ed.) Insects as Natural Enemies: a Practical Perspective. Springer, Dordrecht, The Netherlands.

Hardy, I.C.W., P.J. Ode and M. Siva-Jothy. 2005. Mating systems. Pages 261-298 In: M. Jervis (Ed.) Insects as Natural Enemies.

Ode, P.J., K.R. Hopper and M. Coll. 2005. Oviposition vs. offspring fitness in Aphidius colemani parasitizing different aphid species. Entomologia Experimentalis et Applicata 115:303-310.

Olson D.L. and J.J. Knodel. 2005. Are all Flea Beetles the Same? Crucifer Flea Beetle Versus Leafy Spurge Flea beetles. NDSU Coop. Extn. Publ., E-1274

Olson, D.L. 2004. Aphthona flea beetle population development and leafy spurge growth pattern across a diversity of habitats in North Dakota. Leafy Spurge News. Agric. Exp. Stat., NDSU Ext. Serv. Vol. 26, Issue 1 August.

Olson, D.L. 2004. Decline in flea beetle numbers probably due to variety of factors. Noxious Weed Quarterly, North Dakota Dept. of Agric. Vol. 1, No. 3.

Richardson, Laurie, A. 2004. Interaction of Imazapic, Aphthona spp. Biological Control Agents and Native Grasses for Leafy Spurge (Euphorbia esula) Control. M.S. Thesis, North Dakota State Univ. 55 p.

Wu, Z., K.R. Hopper, P.J. Ode, R.W. Fuester, M. Tuda and G.E. Heimpel. 2005. Absence of single-locus complementary sex determination in Heterospilus prosopidis (Hymenoptera: Braconidae). Heredity 95: 228-234: a Practical Perspective. Springer, Dordrecht, The Netherlands.

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