Source: CORNELL UNIVERSITY submitted to
USE OF AN INSECT PARASITIC NEMATODE TO CONTROL THE NEW INVASIVE WOODWASP, SIREX NOCTILIO, ATTACKING PINES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0213102
Grant No.
(N/A)
Project No.
NYC-139419
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2007
Project End Date
Sep 30, 2010
Grant Year
(N/A)
Project Director
Hajek, A. E.
Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853
Performing Department
ENTOMOLOGY
Non Technical Summary
The pine-killing woodwasp, Sirex noctilio, is one of the top 10 most serious forest insect pest invaders worldwide. This woodwasp attacks numerous species of pines and is particularly threatening because it can kill relatively healthy trees. S. noctilio is native to Europe but has caused extensive losses in non-native pine plantations in numerous countries in the southern hemisphere where it has been introduced. This woodwasp was first found in North America in 2004 and has spread through much of New York and into Pennsylvania and Michigan since then. A parasitic nematode (Deladenus siricidicola) that is specific to wood wasps has been introduced for very successful biological control of S. noctilio in the southern hemisphere. Deladenus siricidicola has never been tested for control of Sirex noctilio in areas where New York's native species of pines are native or naturalized. There is great interest in introducing this nematode to North America for control of S. noctilio but the situation in North America differs from that in the southern hemisphere, where many of the susceptible pines have been introduced and are grown in plantations and there are no native Sirex species. Our study will investigate potential non-target effects of this nematode, whether the species of pine present in the northeastern U.S. are acceptable to the nematode and we will begin to investigate methods for release of the nematode, given that our first two objectives yield promising results.
Animal Health Component
(N/A)
Research Effort Categories
Basic
30%
Applied
40%
Developmental
30%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2153110111050%
2153130111050%
Goals / Objectives
The pine-killing woodwasp, Sirex noctilio, is one of the top 10 most serious forest insect pest invaders worldwide. This woodwasp attacks numerous species of pines and is particularly threatening because it can kill relatively healthy trees. S. noctilio was first trapped in the field in North America in Fulton, NY in fall 2004 and it has been spreading ever since. Biological control and silvicultural management have effectively reduced damage caused by S. noctilio in southern hemisphere pine plantations. The most successful biological control strategy has been introduction of a parasitic nematode, Deladenus siricidicola, which originally came from Europe, the native home of S. noctilio. This study will work toward potential use of this nematode for biological control of S. noctilio in North America. The three objectives of the study include 1. To address issues of environmental safety, we will evaluate interactions between D. siricidicola and non-target invertebrates inhabiting pines in New York State; 2. We will evaluate the effect of pine species on levels of parasitism of Sirex noctilio by Deladenus siricidicola. D. siricidicola has not been tested in the main species of pine occurring in New York State, e.g., eastern white pine (Pinus strobus) and red pine (Pinus resinosa). This study will also provide information on the success of the primary pest, S. noctilio, in the different species of pines in New York; and 3. We will compare the efficacy of different strategies for introducing the insect parasitic nematode Deladenus siricidicola for control of Sirex noctilio. Release methods that have been developed in the southern hemisphere are appropriate for exotic pine plantations. We will test release methods that would be more appropriate for the common types of pine plantings and forests in New York State and the northeastern U.S.
Project Methods
To evaluate non-target impacts of Deladenus siricidicola, pine trees in 3-5 locations in New York will be girdled, weakened with herbicide or felled to allow the diversity of pine-boring arthropods and their associates to invade them. Logs will be taken to the quarantine on Cornell campus where D. siricidicola will be inoculated into trees using a wad punch. After varying lengths of time, logs will be caged and all emerging invertebrates will be evaluated to detect potential parasitism by D. siricidicola. In addition, some of the logs will be split open to collect invertebrates that might not emerge. We will evaluate cause of death of any dead invertebrates found within trees but will also check living individuals for presence of the nematode. There are native species of Deladenus parasitizing the native Sirex and other native siricids. Using molecular methods, we will confirm whether Deladenus that are collected are the species we've released or a native species. We will continue investigating non-targets (especially native species of Sirex) throughout the 3 years of this study. To evaluate the success of D. siricidicola in different pine species, trap logs of different species of pine present in New York will be placed in the field as well as presented to female S. noctilio in the laboratory, so that they become infested by S. noctilio. D. siricidicola will then be inoculated into logs and adult S. noctilio emerging one year later will be collected to evaluate parasitism by D. siricidicola. Wood chips will be used as an additional method for quantification of nematodes in different pines. The next objective will require a permit to release D. siricidicola in the field. Our results from non-target testing will be provided to APHIS to obtain a permit for field studies. We plan to use methods for introducing D. siricidicola to sirex-infested pine bolts that have been developed in Australia. D. siricidicola will be obtained and we will work in sirex-infested stands where sirex presence and densities will be determined using the optimal methods available. We will inoculate differing numbers of pine bolts with D. siricidicola in replicates of 3-5 types of pine stands representative of New York forests and plantings (chosen in collaboration with DEC and stakeholders). Nematode-inoculated bolts will be left in pine stands to be attacked by S. noctilio which will subsequently emerge to attack other trees. Results will be evaluated by rearing S. noctilio to detect nematodes from bait logs and success of releases will be based on presence and abundance of D. siricidicola in logs or girdled trees. This objective is dependent on this nematode being environmentally safe, which will be addressed by Objective 1 during year 1. If we are not granted a permit for these field studies, we will instead put more efforts into non-target studies.

Progress 10/01/07 to 09/30/10

Outputs
OUTPUTS: Results from this study have been summarized in an undergraduate honors thesis at Cornell University, written by Alexandra Jimenez and presented by Alex as a poster and an oral presentation. A graduate student, Elizabeth Erin Morris, is now involved with this project for her doctoral dissertation and is presently writing the results for one chapter of her thesis. Non-target studies are being conducted in collaboration with Dr. David Williams, USDA, APHIS. Results from our studies are of great interest to federal land managers and scientists and will help them to choose whether this parasitic nematode will be used for biological control in the United States. Our findings have been reported at conferences and during university seminars. PARTICIPANTS: Individuals working on the project: Ann E. Hajek, Charlotte Nielsen, Stefan Long, Alexandra Jimenez, E. Erin Morris. Collaborators: David W. Williams, Victor Mastro, Kelley Zylstra (USDA, APHIS, PPQ, CPHST)and Kevin Dodds, USDA, Forest Service. Training: Alex Jimenez, Cornell undergraduate conducting an independent research project and Cornell undergraduate Susan Finkbeiner. E. Erin Morris, doctoral graduate student is conducting her doctoral research on the Sirex-parasitic nematode. TARGET AUDIENCES: Land managers working with pines and Sirex noctilio. Ecologists and environmentalists with interests in invasive species and biological control. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
In fall 2007, Deladenus siricidicola, obtained from Ecogrow in Australia, was injected into pines. Trees were harvested in March 2008, insects were reared from the wood and our laboratory evaluated whether this nematode was present in all emerging non-siricids. We dissected 974 insect specimens, including beetles (at least 10 species from 4 families) and parasitic wasps (at least 4 species from 2 families), checking for parasitic nematodes. We found nematodes in only 9 specimens, one of which was an ichneumonid wasps (a parasitoid attacking cerambycids) and the other 8 were beetles. We collected one specimen of a genus previously known as a host of D. siricidicola (Serropalpus)but did not find nematodes in it. In fall 2008, pines were injected with D. siricidicola and our laboratory diagnosed emerging non-targets: 202 ibaliids and 6 ichneumonids (all Rhyssa), none of which contained parasitic nematodes. We have non-target samples from trees inoculated with D. siricidicola in fall 2009 (141 ibaliids, 11 Rhyssa, 1 Megarhyssa, 490 bark beetles and 3 insects that are presently unknown) and these samples are presently being processed. Deladenus siricidicola was already present in North America before the Ecogrow nematodes were released. When Sirex larvae are not present in trees, D. siricidicola grows and reproduces while feeding on the growing tips of Amylostereum areolatum, the symbiotic white rot fungus carried by S. noctilio and other Sirex. We investigated the diversity of strains of A. areolatum carried by Sirex noctilio and native siricids in the northeastern US using nuclear ribosomal internal transcribed spacers (ITS), nuclear ribosomal intergenic spacers (IGS) and vegetative compatibility groups (VCGs). We detected two strains of A. areolatum in samples from New York State and Pennsylvania. We used five isolates of A. areolatum (including these two strains) to compare growth of D. siricidicola. The nematode increased on all strains of A. areolatum but did not increase when provided with the native Amylostereum chailletii. Strains of A. areolatum differed in growth rates but nematode growth was not always associated with fungal growth rate. The extent that these laboratory results reflect activity within trees is not known although results from this study have implications for mass production of this nematode (mass production is accomplished using the fungus-feeding form of the nematode and not the Sirex-parasitic form). We investigated the effect of different pine species on growth D. siricidicola. We grew A. areolatum in Petri dishes containing A. areolatum and either ground, gamma-irradiated scots, white or red pine. Nematodes survived in plates with each species of pine but results did not conclusively demonstrate improved growth on a specific pine species. We also studied the hymenopteran parasitoids associated with Sirex species in New York State. The most common parasitoid, Ibalia leucospoides ensiger, is most abundant in smaller diameter wood while more S. noctilio females emerged from larger diameter wood, suggesting that this parasitoid could have more impact on male than female S. noctilio.

Publications

  • Morris, E.E., Williams, D., Hajek, A.E. 2011. Trading places: fungus and nematode switch off as predator and prey. USDA, Forest Service, Northern Res. Stn., Gen. Tech. Rpt. (in press).


Progress 10/01/08 to 09/30/09

Outputs
OUTPUTS: The pine-killing woodwasp, Sirex noctilio, is one of the top 10 most serious forest insect pest invaders worldwide. This woodwasp attacks numerous species of pines and is particularly threatening because it can kill relatively healthy trees. S. noctilio was first trapped in the field in North America in Fulton, NY in fall 2004 and it has been spreading ever since. Biological control and silvicultural management have effectively reduced damage caused by S. noctilio in southern hemisphere pine plantations. The most successful biological control strategy has been introduction of a parasitic nematode, Deladenus siricidicola, which originally came from Europe, the native home of S. noctilio. This study will work toward potential use of this nematode for biological control of S. noctilio in North America. Our results to date have been summarized in an undergraduate honors thesis at Cornell University by Alexandra Jimenez and presented by Alex as a poster and an oral presentation. A graduate student, Elizabeth Erin Morris, is now involved with this project for her doctoral dissertation. Non-target studies are being conducted in collaboration with Dr. David Williams, USDA, APHIS. Results from our studies are of great interest to federal land managers and scientists and will help them to choose whether this nematode will be used for biological control in the United States. Our findings have been reported at conferences and during university seminars. PARTICIPANTS: Individuals working on the project: Ann E. Hajek, Stefan Long, Charlotte Nielsen; Collaborators: David W. Williams, Victor Mastro, Kelley Zylstra (USDA, APHIS, PPQ, CPHST), Kevin Dodds, USDA, Forest Service; Training: Alexandra Jimenez, Cornell undergraduate conducting an independent research project; Susan Finkbeiner, Cornell undergraduate. TARGET AUDIENCES: Land managers working with pines and Sirex noctilio. Ecologists and environmentalists with interests in invasive species and biological control. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Before the biological control nematode Deladenus siricidicola can be released in New York State the potential effects on non-target organisms must be evaluated (along with efficacy). USDA, APHIS scientist David Williams has been conducting controlled releases of this nematode in New York State. At 4 New York State sites, Sirex noctilio-struck pines were identified. In October 2007, Deladenus siricidicola, obtained from Ecogrow in Australia, was injected into trees, following guidelines developed by Robin Bedding. Trees were harvested in March 2008, bolts were placed into barrels and insects emerging were collected and frozen until dissection. Our APHIS collaborators who hold permits for the releases retained the siricids but sent non-siricids to our laboratory to check for parasitic nematodes. We dissected a total of 974 insect specimens, including beetles (at least 10 species from 4 families) and parasitic wasps (at least 4 species from 2 families), checking within them for parasitic nematodes. We found nematodes in only 11 specimens, two of which were parasitic wasps and the other 9 were beetles. In the literature, D. siricidicola has only been reported parasitizing a melandryid beetle (Serropalpus) and four species of Sirex. We collected one specimen of the same genus of melandryid (Serropalpus) but did not find any nematodes in it. Specimens with nematodes have been stored and will be checked using molecular methods when possible (see following). Dr. Williams and others found that Deladenus siricidicola was already present in North America before the Ecogrow nematodes were released. Whether the D. siricidicola already present was a native parasite of native siricids or had been introduced with S. noctilio is unknown. Regardless, in order to both evaluate efficacy of releases of the Australian nematodes (which originated in Hungary) and effects on non-targets it is necessary to be able to differentiate between these nematodes. We have investigated several regions of the genome of these nematodes and are developing methods for differentiating between these two strains of D. siricidicola. We have also been interested in the effect of different pine species on activity of the symbiotic fungus and the nematode. Toward this objective, we had pine samples sterilized using gamma radiation and grew fungus on plates containing ground scots, white or red pine. Methods for continuing these studies in order to evaluate nematode growth are being developed.

Publications

  • Long, S.J., D.W. Williams, A.E. Hajek. 2009. Sirex species (Hymenoptera: Siricidae) and their parasitoids in Pinus sylvestris in eastern North America. Can. Entomol. 141: 153-157.


Progress 10/01/07 to 09/30/08

Outputs
OUTPUTS: The invasive woodwasp Sirex noctilio is native to Europe but has been introduced throughout the southern hemisphere to areas where pines from the northern hemisphere are grown. This pine-killing woodwasp carries a symbiotic fungus, Amylostereum areolatum, a wood-rotting white rot basidiomycete, which adult females inject into trees when they lay eggs. Sirex noctilio was first found in New York State next to the southeastern shore of Lake Ontario in 2004 and it has been spreading since then; S. noctilio has never before been introduced to an area where pines and Sirex species are native but this invasive species is already thought to be more aggressive than the native North American woodwasps, which are thought to attack only very weakened trees. We conducted a study comparing strains of the genus Amylostereum carried by Sirex species in the northeastern US and a manuscript for a peer-reviewed journal is virtually complete. We also conducted a study of the hymenopteran parasitoids attacking species of Sirex in central New York State. Three species of parasitoids emerged from wood that was heavily infested with Sirex noctilio and lightly infested by the natives Sirex edwardsii and Sirex nigricornis. The most common of these parasitoids, Ibalia leucospoides ensiger, was more abundant in smaller diameter scots pine while the percentage of Sirex noctilio females (versus males) was higher in larger diameter scots pine. These data have also been written for publication in a peer-reviewed scientific journal. A major goal of our studies is to investigate the potential for release of the parasitic nematode Deladenus siricidicola to control Sirex noctilio; a Hungarian strain of this nematode has been introduced throughout the southern hemisphere for biological control of Sirex noctilio and in some instances this nematode has been a key factor in controlling outbreak S. noctiio populations. This nematode has two phases, one of which parasitizes and sterilizes Sirex noctilio which vectors it, and the second phase feeds on A. areolatum. The fungal-feeding phase is used for commercial mass production of this nematode in Australia. We have been comparing seven different media to optimize growth of A. areolatum. We are helping to evaluate arthropod samples from trees infested by D. siricidicola to determine potential effects of D. siricidicola on non-targets and thus far, through our dissections of hymenopteran parasitoids and beetles that emerged from trees in which D. siricidicola was released, we have found no non-target infection by this nematode. In samples of native siricids trapped in the mid-Atlantic and southeastern US, we found native nematodes that we hypothesize are closely related to D. siricidicola. PARTICIPANTS: Individuals working on the project: Ann E. Hajek, Charlotte Nielsen, Stefan Long Collaborators: David W. Williams, Victor Mastro, Kelley Zylstra (USDA, APHIS, PPQ, CPHST) Kevin Dodds, USDA, Forest Service Training: Alex Jimenez, Cornell undergraduate conducting an independent research project; Susan Finkbeiner, Cornell undergraduate. TARGET AUDIENCES: Land managers working with pines and Sirex noctilio. Ecologists and environmentalists with interests in invasive species. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The woodwasp Sirex noctilio is a recent invader in the northeastern US and we know little about how this pine-killing woodwasp will interact in this ecosystem. S. noctilio has never before been introduced to a habitat where pines and their associated communities, including woodwasps, are native. S. noctilio females carry a white rot basidiomycete fungus, Amylostereum areolatum, and inject it into trees when they lay eggs. The fungus begins growing and rotting the tree and the S. noctilio immatures grow while feeding on fungal-infested wood. We have been investigating the diversity of strains of the genus Amylostereum carried by Sirex noctilio and native siricids in the northeastern US. In fact, this aspect of the native North American siricids is poorly known but must be studied to understand the impact of S. noctilio on native woodwasps. Isolates of the fungal symbionts carried by the invasive woodwasp Sirex noctilio and native woodwasps in the genus Sirex from New York State and Pennsylvania were compared, using nuclear ribosomal internal transcribed spacers (ITS), nuclear ribosomal intergenic spacers (IGS) and vegetative compatibility groups (VCGs). Data analysis has been completed and a paper for a peer-reviewed journal is virtually complete. We have also been studying the hymenopteran parasitoids associated with Sirex species in New York State and these data will help us to understand the extent to which native parasitoids are attacking this new invasive. Our results show that the most common parasitoid, Ibalia leucospoides ensiger, is most abundant in smaller diameter wood while more S. noctilio females emerged from larger diameter wood, suggesting that this parasitoid could have more impact on male S. noctilio than female. Our laboratory is interested in the potential for release of the Sirex noctilio-parasitic nematode Deladenus siricidicola which has been used extensively for successful control of S. noctilio in the southern hemisphere. Because this nematode can be mass produced on A. amylostereum, we have been comparing media toward optimizing growth of this fungus and we will continue these studies toward optimizing growth of D. siricidicola. The potential impact of D. siricidicola on non-target organisms must be understood before this nematode could be considered for release for S. noctilio control in the US. Our laboratory has been evaluating the potential for impact of the nematode on hymenopteran parasitoids attacking S. noctilio; to date, we have found no parasitism of non-targets by D. siricidicola. However, we have detected native nematodes that are closely related to D. siricidicola in samples of Sirex species from the mid-Atlantic and southeastern US. D. siricidicola could compete with native sirex-parasitic nematodes in the US if these attack the same siricid species and feed on the same fungal species but to date little is known about the native nematodes parasitizing native Sirex species.

Publications

  • No publications reported this period