Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Since its introduction into the Southern Appalachians in the 1950s, the balsam woolly adelgid, Adelges piceae, has reduced native populations of Fraser fir, Abies fraseri, and requires chemical treatments for Christmas tree growers. Adelges piceae-resistant Fraser fir trees would lessen costs for the Christmas tree industry and assist in the restoration of native stands. A time- and cost-effective technique has been developed for infesting Abies seedlings with Adelges piceae. The technique involves suspending heavily infested bolts above the noninfested plants and allowing the crawlers to hatch and fall onto the trees, mimicking wind dispersal. Crawler density immediately under and within a 30 cm band underneath the log can range from 500 to over 3000 individuals within a 58 cm2 area. Three studies into artificially infesting severed Abies branches suggest that these cuttings can be maintained long enough to produce at least one generation of A. piceae; this technique may be useful in early resistance screening trials. PARTICIPANTS: Leslie Newton is a PhD candidate that has been working on the project. TARGET AUDIENCES: The target audience is Fraser fir Christmas tree growers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The suspended bolt technique mimics natural dispersal and is highly effective in producing heavy A. piceae infestations in a time-efficient manner. This technique can be utilized for large or small studies and can be adapted for infestations of other wind-dispersed insects. Bolts of heavily infested Fraser fir are capable of producing tens of thousands of A. piceae crawlers and could be hung for a period of time over one set of trees and moved to another set of trees, thus economizing the number of bolts required for infestations. The technique of tying individual pieces of infested bark to trees is effective, although time consuming, and can be utilized in small studies or studies requiring infestation of specific areas of a tree rather than the entire tree. The cut branch experiments are promising for providing a nondestructive technique for initial host resistance screening trials.
Publications
- Newton, L., F. Hain, and J. Frampton. 2009. Host resistance screening for balsam woolly adelgid: Early results from 13 fir species. Proc. 9th International Christmas Tree Res. and Ext. Conf. IUFRO Unit 2.02.09: 51-54.
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: We are currently utilizing the suspended bolt technique and the cut branch technique for a comprehensive program of host resistance screening of multiple fir species. We are pursuing three screening strategies to search for resistance: 1) grafts of long-term surviving trees from natural Fraser fir stands in Great Smokey Mountain National Park, 2) surviving Turkish and Trojan fir seedlings from a Phytophthora inoculation trial, and 3) genetically diverse populations of Fraser fir seedlings. Our current efforts are focused on screening for resistance. A logical complement to screening is an investigation into the mechanisms of resistance. The goal of this project is to clarify the BWA resistance/susceptibility mechanisms between and within fir species. Plant defenses are expressed during different stages of insect use of its host plant. Within and between susceptible host plant species there is a continuum of tolerance to the insect which may be expressed at 2 levels. First, the host may have enough defenses to ward off the initial infestation. Host tree surface and/or internal chemistry may be too toxic for the insect to survive. Alternately, the insect may be unable to physically locate a suitable feeding site due to either parental adaptation to an alternate host or host tree structure and function prohibit successful feeding. Second, the host may tolerate levels of infestation and natural enemies maintain population densities below a threshold level that would otherwise result in host tree mortality. Finally, the host tree may be susceptible to the insect, lack natural enemies to maintain the population and die from indirect consequences of feeding. Our hypotheses are: Fraser firs are highly susceptible to BWA. However, some fir trees have survived. Other fir species display considerable resistance to BWA. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Fraser fir Christmas tree growers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This project will identify differences in probing behavior of resistant and susceptible fir species. This information will then be used in subsequent studies to assay fir species and hybrids for resistance to BWA. Additionally, information will be obtained on what substrates the adelgid ingests and possible extra-oral digestion of these substrates. The project will also provide a clearer understanding of the role of bark juvabione concentration (this aspect of the project will probably not be completed during the first 2 years of funding) and bark texture in resistance to BWA. Finally the project will provide an indication of the genetic control of juvabione production in Fraser fir. This trait may be useful for early indirect selection to establish a BWA resistant population of Fraser fir.
Publications
- No publications reported this period
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Our long term objective is to reduce chemical inputs for balsam woolly adelgid (BWA) on Christmas tree plantations by developing genetically resistance Christmas tree stock. To this end, our short term objectives were to: 1) Develop reliable techniques for artificially infesting and bioassaying fir seedlings for resistance to BWA; and 2) Begin screening for host resistance to BWA across multiple fir species and within Fraser fir. We have conducted five studies relating to these objectives: 1) An infestation techniques study was conducted from July 2006 to June 2007; three different techniques (tying infested bark to seedlings, placing infested bark at base, hanging infested logs over seedlings) were tested for infesting young Fraser fir trees with BWA. We utilized two ages of Fraser fir (2- and 6-year old seedlings); a total of 144 trees were included in the study. 2) We conducted a crawler abundance and dispersal study, in which Fraser fir bolts heavily infested with BWA were suspended over a grid for five days; BWA crawlers fell from the bolt onto the grid and were trapped in an adhesive material. The crawlers were counted and dispersal patterns noted. 3) A novel approach for initial screening trials was tested, in which we infested tips of branches cut from Fraser fir and Veitch fir seedlings and mature trees. 4) We conducted a study of Fraser fir resistance to BWA in a clonal seed orchard (October 2006); 1200 trees were included in this study - we correlated BWA infestation levels with various traits such as bark thickness and bark appearance, and calculated the heritability of various traits. 5) A BWA host resistance screening trail across multiple fir species was conducted from August 2007 to May 2008. Thirteen fir species (three seed sources within Fraser fir) were tested (720 total trees) for comparative responses to BWA infestation. PARTICIPANTS: Leslie Newton, Graduate Student TARGET AUDIENCES: North Carolina Christmas tree growers PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Four of the above studies have been completed and analysis is underway for the fifth. 1) We have developed an effective and efficient technique for infesting Fraser fir seedlings with the balsam woolly adelgid. This technique has been adapted for host resistance studies involving hemlocks and the hemlock woolly adelgid. 2) From the crawler abudance and dispersal study, we learned that through the bolt-suspension technique, seedlings are exposed to thousands of BWA crawlers. The bolts can be placed approximately one foot apart to effect a uniform pattern of coverage. 3) Infesting cut branch tips (hydrating the tips in water) is an effective technique for rearing BWA in the lab (a potential source for maintaining BWA throughout the year for studies or predator rearing) and may be used as a method for conducting non-destructive screening throughout the native range of Fraser fir. 4) The clonal Fraser fir study taught that, although there was no evidence of immunity to BWA, there do appear to be clonal differences. We are conducting a neighborhood analysis to determine if the differences are related to spatial autocorrelation rather than genetics. 5) The multiple fir species sreening study is currently being assessed; early results indicate that BWA crawlers settle preferentially on the buds of young fir trees, regardless of species. BWA development from first to second or third instar was observed and individual trees showed signs of reaction to the insect in the form of swelling (gouting) at the feeding site. However, it is too early to form any definitive conclusions.
Publications
- No publications reported this period
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Progress 10/01/06 to 09/30/07
Outputs
Information from this project has been disseminated through the following public presentations at professional meetings: Newton, L. and F. Hain. 2006. Balsam woolly adelgid: survivor firs in GSMNP and artificial infestation of Fraser fir seedlings. Southern Appalachian Forest Entomology and Pathology Seminar, Crossnore, NC. Mar. 9-10. Newton, L., F. Hain, and J. Frampton. 2006. Host resistance to balsam woolly adelgid in and IPM strategy for Christmas trees. North American Forest Insect Work Conference. Asheville, NC. May 22-26. Hain, F. 2006. Forests in crisis: The threat of exotic insects. Society of American Foresters National Convention. Oct. 25-29. Newton, L., F. Hain, and J. Frampton. 2006. Survivor Fraser fir (Abies fraseri) in the Great Smoky Mountains National Park. Entomological Society of America National Meetings. Dec. 11-13.
Impacts
Insect host resistance screening requires an effective technique for artificially infesting the material under observation, so that both host responses to the insect and insect responses to the host can be assessed. Past methodologies have relied primarily upon the application of BWA-infested bark pieces to fir trees of various ages by pinning or tying the infested bark to the stem of the tree. This is an effective method, but it is time consuming, requires repeated applications, and the insects on the bark pieces are sometimes damaged in the process. We have developed a method in which infested bolts of fir are suspended over the material to be infested and the crawlers allowed to simply drop onto the material, mimicking the natural process of infestation. This technique can be utilized in both laboratory and greenhouse trials with minimal time involvement and maximum exposure to BWA crawlers. Additionally, we will present a new and relatively nondestructive technique
for host resistance screening throughout the native range of Fraser fir by infesting branch tips cut from living trees. This technique has been successfully employed with both seedlings (5 year old) and mature (20 year old) Fraser fir.
Publications
- No publications reported this period
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Progress 10/01/05 to 09/30/06
Outputs
Balsam Woolly Adelgid infestations were noted on a number of trees in the Crossnore Fraser fir clonal seed orchard in August 2006. Permission was sought and granted for a full assessment of the orchard. Over 96% of the trees were infested with BWA. There were no clone differences in percent infested but there was a significant year difference. Although there were a few individual trees with no visible BWA infestations, every clone was susceptible at some level to this insect. Of the 59 clones, 28 had infestation levels ranging from no infestation to heavy infestation (0 to 3); 27 ranged from light to heavy (1 to 3); three (clones 23, 148 and 227) ranged from moderate to heavy (2 to 3); and one (clone 278) was always heavily infested (3).
Impacts
We expect to determine if resistance to the balsam woolly adelgids exists in the Fraser fir population. If it does, we will begin a program to select for resistant trees. If it does not, we will determine if resistance can be established in hybrids of Fraser fir and other fir species that are resistant.
Publications
- No publications reported this period
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Progress 10/01/04 to 09/30/05
Outputs
The goal of the spruce spider mite work is to develop an IPM system on Fraser fir Christmas trees that relies on maintaining a habitat (ground cover) for natural enemies. We have established 2 plantations with various ground covers to determine the optimum covers for natural enemies and tree growth. The balsam woolly adelgid work is concerned with understanding host resistance. Various fir species seedlings have been potted and varios bioassay techniquesn are being evaluated. A reliable technique is necessary so that screening studies can begin. We have also improved the technique for analysis of juvabione, a defensive compound, in the bark tissue. Finally, we are testing various diets for artificially rearing balsam woolly adelgid.
Impacts
The work on biological control of spruce spider mite should result in a pest management plan for Fraser fir Christmas trees that will maintain a predator friendly ground cover and minimize insecticde use. The host resistance work on balsam woolly adelgid should clarify the liklihood of Fraser fir survival in natural stands, and the possibility of screening for resistant Fraser fir for the Christmas tree industry.
Publications
- Newton, L.P. and F.P. Hain. 2005. Host interactions of the balsam woolly adelgid. Pp. 199-209. In: Onken, B. and R. Reardon (compilers) Third Symposium on hemlock woolly adelgid in the eastern United States. USDA For. Serv. FHTET-2005-01. 384 pp.
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Progress 10/01/03 to 09/30/04
Outputs
The goal of the spruce spider mite work is to develop an IPM system on Fraser fir Christmas trees that relies on maintaining a habitat (ground cover) for natural enemies. Surveys of selected plantations with different cover types has been completed and the data is being analyzed. We are in the preocess of establishing 2 plantations with various ground covers to determine the optimum covers for natural enemies and tree growth. The balsam woolly adelgid work is concerned with understanding host resistance. Various fir species seedlings have been potted in preparation for developing a bioassay technique. We will develop a reliable technique so that screening studies can begin. We have also improved the technique for analysis of juvabione, a defensive compound, in the bark tissue. Bark samples from surviving mature Fraser firs from the Great Smoky Mountains National Park have been collected for analysis.
Impacts
The work on biological control of spruce spider mite should result in a pest management plan for Fraser fir Christmas trees that will maintain a predator friendly ground cover and minimize insecticde use. The host resistance work on balsam woolly adelgid should clarify the liklihood of Fraser fir survival in natural stands, and the possibility of screening for resistant Fraser fir for the Christmas tree industry.
Publications
- No publications reported this period
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Progress 10/01/02 to 09/30/03
Outputs
Arthropods were collected in a survey of beneficials in Fraser fir Christmas tree plantations with native ground covers during the summer of 2002. Currently they have been sorted to Order and over 50% to family, some to genus or species. The data has been added to a data base. The suitability of various ground covers as predator habitat for spruce spider mites is being evaluated. Twig cuttings and bark samples have been collected from mature Fraser fir in the Great Smoky Mountain National Park that have survived the balsam woolly adelgid attack. The cuttings have been grafted onto root stock. The bark samples are being processed for juvabione analysis. Bark samples from a plantation of apparently immune Veitch's fir have also been collected for juvabione analysis. Plantings of several fir species with various degrees of resistance to balsam woolly adelgid is in progress.
Impacts
The work on biological control of spruce spider mite should result in a pest management plan for Fraser fir Christmas trees that will maintain a predator friendly ground cover and minimize insecticde use. The host resistance work on balsam woolly adelgid should clarify the liklihood of Fraser fir survival in natural stands, and the possibility of screening for resistant Fraser fir for the Christmas tree industry.
Publications
- No publications reported this period
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Progress 10/01/01 to 09/30/02
Outputs
The spruce spider mite project consisted of taking samples from Fraser fir Christmas tree foliage and the surrounding ground cover in 4 plantations that represented different management strategies. The management stategies ranged from intensive weed control to light weed control. Sampling was done throughout the growing season to determine the number and type of natural enemies in the system. The data is currently being analyzed. The balsam woolly adelgid project consisted of sampling for juvabione in natural stands and a plantation in the Great Smoky Mountain National Park. Samples were taken from 108 old growth Fraser fir that have survived the adelgid infestation. In the plantation 125 samples were taken on a monthly basis to evaluate seasonal fluctuations in juvabione concentrations. Part of the plantation consisted of a half-sib planting. From 315 of the half-sib trees bark samples were taken for juvabione analysis. On an additional 6 trees, wood samples were
also taken to correlate wood and bark juvabione concentrations. GC and data analysis is currently in progress.
Impacts
The expected impact of the spruce spider mite project will be a better management stategy for ground cover that will encourage natural enemies. For the balsam woolly adelgid project, the expected impact is a better understanding of the mechanisms and genetic control of host resistance to the adelgid.
Publications
- No publications reported this period
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Progress 10/01/00 to 09/30/01
Outputs
A proposal entitled "resistance mechanisms of Fraser fir to balsam woolly adelgid infestation" was partially funded by USDI Park Service. The objectives are: (1) To investigate the potential resistance of Fraser fir to balsam woolly adelgid (BWA) by evaluating juvabione concentrations and bark thickness in surviving mature Fraser fir within the Great Smoky Mountain National Park (GSMNP). (2) To investigate the potential resistance of Fraser fir to BWA by evaluating juvabione concentrations in a half-sib plantation of infested Fraser fir within the GSMNP. (3) to preserve the genotypes from trees with apparent BWA resistance and/or high juvabione production by collecting scions and grafting them onto seedling stock. To date bark samples have been collected from 67 trees in natural stands, and the juvabione analysis is in progress.
Impacts
(N/A)
Publications
- Fowler, G., J. Zhang, F.P. Hain, and J.F. Manville. 2001. The distribution pattern of two juvenile hormone related compounds in Fraser fir and the induced response to a balsam woolly adelgid infestation. Can. J. For. Res. 31: 1701-1707.
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Progress 10/01/99 to 09/30/00
Outputs
Several manuscripts have been submitted for publication. No additional field or laboratory research was accomplished during the past 12 months. A proposal entitled "resistance mechanisms of Fraser fir to balsam woolly adelgid infestation" has been submitted to the State Partnership Program, USGS. If funded, the objectives will be: (1)To investigate the potential resistance of Fraser fir to balsam woolly adelgid (BWA) by evaluating juvabione concentrations and bark thickness in surviving mature Fraser fir within the Great Smoky Mountain National Park (GSMNP). (2) To investigate the potential resistance of Fraser fir to BWA by evaluating juvabione concentrations in a half-sib plantation of infested Fraser fir within the GSMNP. (3)To preserve the genotypes from trees with apparent BWA resistance and/or high juvabione production by collecting scions and grafting them onto seedling stock.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 01/01/99 to 12/31/99
Outputs
Studies were carried out to determine what effect topically applied juvabione and kinoprene, both juvenile hormone analogs, had on balsam woolly adelgid reproduction. Juvabione treated adelgids treated with a single application of juvabione generally did not differ in egg production or eclosion than water treated controls. However, some exceptions suggested further testing with multiple applications. Acetone had a stimulatory effect on adelgid fecundity and eclosion. Kinoprene did not seem to affect adelgid reproduction. When adelgid woolly masses were topically treated with multiple applications of juvabione, crude bark extract, acetone, or no treatment, adelgids treated with juvabione demonstrated significantly lower fecundity than controls after 2, 4 and 6 applications. Bark extract treated adelgids tended to have lower fecundity than controls but not significantly. Eclosion data revealed no significant differences with the exception of acetone, which was higher
than all other treatments following 6 applications. Since juvabione is present within the bark of Fraser fir, these results indicate that juvabione may have potential as a host resistance mechanism against the adelgid.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 01/01/98 to 12/31/98
Outputs
The objective was to compare endogenous juvabione distribution and quantity between uninfested Fraser firs and firs which are infested with the balsam woolly adelgid, Adelger piceae. The mean juvabione concentration for each infested fir was higher than their uninfested counterparts. The infested middle regions had mean juvabione values that were significantly higher than the uninfested middle regions. No other significant differences were observed. Two of the infested Fraser firs which maintained their apical dominance demonstrated the highest measured levels of juvabione in the upper region of all the infested firs. These results indicate that juvabione can be an induced response to adelgid attacks, and that trees which produce large quantities of this compound may possess tolerance or resistance to the adelgid. A second objective was to determine what effect topically applied juvabione had on balsam woolly adelgid fecundity and eclosion. Juvabione treated adelgids
generally exhibited lower egg means and eclosion rates than water treated controls. Acetone had a stimulatory effect on adelgid fecundity and eclosion. Further research will investigate the timing and amount of topical applications.
Impacts
(N/A)
Publications
- No publications reported this period
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