Progress 09/01/09 to 08/31/12
Outputs
OUTPUTS: Advanced research training was provided to Dr. Tara Gariepy, a Canadian scientist who has since obtained a permanent research position with Agriculture Canada. We developed and applied multiplex PCR assays to investigate the occurrence of in-host competition between parasitoids and/or hyperparasitoids on melon aphids collected from fields of taro, Colocasia esculenta. To fully document the parasitoid-hyperparasitoid community within A. gossypii, both live and mummified aphids were examined. A total of 818 live and 245 mummified aphids were analyzed using the multiplex assays, with congruent rearing of over 600 mummified aphids serving as a basis for qualitative comparisons in terms of species composition and trophic linkages. Sequence data were obtained from 10 voucher specimens each of A. colemani, A. certus, E. fugitiva, L. testaceipes, B. communis, S. aphidivorus, and P. siphonophorae. Data were made available online (Genbank Accession Nos. HQ599561-HQ599576), and the multiplex assay was described in detail in academic publications (see below). Results were further disseminated in professional conferences and symposia. PARTICIPANTS: Dr. Tara Gariepy served as a post-doctoral researcher and co-PI and developed the molecular techniques used in this project. She has since moved on to a permanent research position with Agriculture Canada. Dr. Holly Johnson replaced Dr. Gariepy and for some months worked to extend the findings and to help train graduate students in the use of multiplex technology for analyzing food webs. Ms. Angel Acebes used the techniques developed to help ascertain the field establishment of a newly introduced Chinese parasitoid in taro agro-ecosystems; and obtained her Master's Degree from the University of Hawaii using these data in her dissertation. TARGET AUDIENCES: All farmers in Hawaii that grow crops attacked by invasive aphid species stand to benefit by advances in methodology to evaluate parasitism and hyperparasitism of these invasive pests. Other biocontrol practitioners, such as the Hawaii Dept. of Agriculture (who list several invasive aphids as key target pests in the islands) may also benefit from the development and use of these new tools. Members of the conservation community that are concerned with the fact that invasive aphids attack many threatened and endangered plant species in Hawaii will also appreciate efforts to improve biological control implementation and evaluation. And other research entomologists around the world that study aphid food webs and biological control can adapt and use our techniques. PROJECT MODIFICATIONS: The co-PI on this proposal, Dr. Tara Gariepy, left Hawaii to take a professional position in Canada. A new post-doc (Dr. Holly Johnson) was hired as a replacement to continue the research. There was a significant delay in research progress due to the need to re-advertise, find, and hire a new scientist with appropriate molecular biology skills on Kauai. Some months after her hire, Dr. Johnson had to leave the project due to illness.
Impacts
Molecular analyses revealed that hyperparasitism and multiparasitism of live aphids is remarkably low, whereas hyperparasitism of mummified aphids was extraordinarily high in both rearing and molecular analyses. The rearing and the DNA methods showed similar trends, with sharp declines in one parasitoid species followed by sharp increases in another during the course of the season. In comparison to reared samples, molecular analysis of the parasitoid community was more complete and permitted the identification of previously unknown or unconfirmed trophic linkages. Using molecular techniques, the ability to identify trophic linkages in a parasitoid community is becoming more refined. Although we failed to detect all linkages in the present study, several undescribed or unconfirmed associations were uncovered using the multiplex PCR assays. The inclusion of B. communis in the multiplex assay allows us to assess establishment, parasitism, and dispersal of this new species following its release in Hawaii.
Publications
- No publications reported this period
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Progress 09/01/10 to 08/31/11
Outputs
OUTPUTS: Experiments were conducted and analyzed to show that multiple PCR assays could be effectively used to document the trophic relationships among aphid pests, their primary parasitoids, and their hyperparasitoids in a system commonly occurring in taro field of Hawaii. Hyperparasitism and multiparasitism of live aphids was very low, whereas hyperparasitism of mummified aphids was extraordinarily high in both rearing and molecular analyses. In comparison to reared samples, molecular analysis of the parasitoid community was more complete, and permitted the identification of previously unknown or unconfirmed trophic linkages Results from the project were presented at professional meetings, including: Classical biocontrol in a new regulatory environment. International Symposium on Biological Control of Arthropods, Christchurch, New Zealand, February 2009. Annual Meeting of Western Regional Research Project W-2185: Biological Control in Pest Management Systems of Plants. Portland, Oregon, March 2009. PARTICIPANTS: Opportunity for training and professional development was provided by the project to the post-doctoral researcher Dr. Tara Gariepy; and to Master's Degree graduate student Angelita Acebes. TARGET AUDIENCES: Target audiences for the detailed research outputs include all farmers in Hawaii with crops that are attacked by the pest aphid Aphis gossypii. For the wider adaptation of the methods developed during the project, almost all farmers in the state with insect pest problems susceptible to attack by predators and parasitoids can benefit from our research results. Other entomologists and ecologists, and land managers, can also apply these findings in other crop and natural ecosystem studies. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
New methods were developed and tested to determine the trophic relationships among primary parasitoids and hyperparasitoids attacking pest aphids in Hawaiian taro fields. The demonstration of this methodology can serve as an example for the study of similar relationships in other pest/natural enemy complexes. The results of this study allow us to better understand the role and the potential of new natural enemies to integrate into the system, and in fact can guide future classical biological control projects.
Publications
- Gariepy, T. D. and Messing, R. H.. 2011. Development and use of molecular diagnostic tools to determine trophic links and interspecific interactions in aphid-parasitoid communities in Hawaii. Biological Control 60: 26-38.
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Progress 09/01/09 to 08/31/10
Outputs
OUTPUTS: Species-specific PCR primers were developed for seven species of primary and hyper-parasitoids that attack the invasive melon aphid, Aphis gossypii, in Hawaii. A multiplex assay was designed that allows us to efficiently and economically detect these primers within individual aphid specimens. PARTICIPANTS: Dr. Russell Messing (PD) managed the project and provided overall guidance, mentoring, help with data interpretation, presentation, and writing. Dr. Tara Gariepy (currently with the University of Guelph Barcoding Project) did the initial work on primer development, specificity testing, and multiplex design. Dr. Holly Johnson used the molecular tools to obtain substantial data on field parasitism rates. Angelita Acebes, a Master's degree graduate student from the Philippines, obtained training and professional development in her use of molecular tools and data as part of her thesis research project. TARGET AUDIENCES: All farmers in Hawaii that grow crops attacked by invasive aphid species stand to benefit by advances in methodology to evaluate parasitism and hyperparasitism of these invasive pests. Other biocontrol practitioners, such as the Hawaii Dept. of Agriculture (who list several invasive aphids as key target pests in the islands) may also benefit from the development and use of these new tools. Members of the conservation community that are concerned with the fact that invasive aphids attack many threatened and endangered plant species in Hawaii will also appreciate efforts to improve biological control implementation and evaluation. PROJECT MODIFICATIONS: The co-PI on this proposal, Dr. Tara Gariepy, left Hawaii to take a professional position in Canada. A new post-doc (Dr. Holly Johnson) was hired as a replacement to continue the research. There was a significant delay in research progress due to the need to re-advertise, find, and hire a new scientist with appropriate molecular biology skills on Kauai.
Impacts
The use of these new molecular tools will enable us to more accurately asses the identities and rates of parasitism on important aphid pests in Hawaiian agro-ecosystems. The information will help us to document establishment and distribution of newly released parasitoid species; and the impact of biotic resistance (hyperparasitism, multi-parasitism) on efficacy of classical biocontrol introductions.
Publications
- No publications reported this period
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