Progress 01/01/10 to 09/30/13
Outputs
Target Audience: Our target audience was commercial and home cucurbit growers in Hawaii. These growers generally operate a diversified production system that includes a variety of cucurbits, brassica, herbs, and other crops. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? A graduate student completed an MS degree during the course of this project. In addition, three undergraduate students conducted directed research projects on pickleworm as part of their undergraduate training. Several other students became involved in the project while enrolled in Foundations of Pest Management (PEPS 421) at UH Manoa. How have the results been disseminated to communities of interest? Jari Sugano and other extension agents have been sharing the results of the research. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
We completed a survey of commercial cucurbit growers. Pickleworm continues to be a major problem for every grower surveyed. We established that there have been growers who have ceased production of cucurbit crops due to pickleworm damage. Those growers continuing to produce cucurbits continue to manage pickleworm by spraying insecticides. There are no other methods of management being used by any of the growers surveyed. A non-replicated field trial was set up at Poamoho Research Station. We evaluated organically approved products such as Entrust, Bt, Beauveria bassiana, and Steinernema feltia. Entrust was the most effective product for pickleworm. As an alternative to insecticides, several essential oils were determined to reduce neonate survivorship through both direct contact and residual contact and vapors. Further experimentation needs to be undertaken to evaluate the potential for these compounds as a pest management tool. During the course of this study, two parasitoids were reared from pickleworm larvae collected in the field. These two parasitoids were not subsequently recovered and so no further research could be conducted on them. Both were Hymenoptera, one was an ichneumonid wasp,Trathala flavoorbitalis,the other an unidentified species of braconid in the genus Apanteles. Laboratory research has yielded some interesting results. In a series of oviposition preference experiments we discovered that pickleworm females do not appear to distinguish between different varieties of cucurbit i.e. in the laboratory setting females did not distinguish or prefer a particular variety of cantaloupe over any other used in the experiments. Laboratory and glasshouse experiments tested the preferences of adult female moths for different crop plants (watermelon, squash, cantaloupe) to ascertain whether a push-pull system could be useful for management of this pest. The aim of this was to evaluate whether this could be a potential alternative to insecticide application or be incorporated into a management plan to reduce insecticide application in this crop. Watermelon was not a deterrent host as suggested by previous literature. We found that female moths readily laid eggs on this plant. There appeared to be a preference for squash over watermelon and cantaloupe, suggesting that this could be a good trap crop/attractant for pickleworm. Thus we determined that pickleworm females do seem to have preferences for different host plants but these preferences appear to change according to the scale in which the experiment is conducted. The female moths exhibited different host plant preferences when offered single leaves of host plants compared to when they were offered whole plants. We also offered female moths’ bean as a potential oviposition site. In this case, females laid fewer eggs overall and more eggs on the cage itself rather than the bean leave. Bean may be a potential push/deterrent crop. Field studies need to be conducted to further evaluate this potential. Due to our observation that neonate larvae are highly mobile we also conducted some experiments to evaluate the longevity of larvae without food and the feeding preferences of neonate larvae. Neonate larvae are able to survive for several days and move quickly across a distance comparable to normal crop row spacing. This suggests that even if adult preferences were not so labile, the neonates could move if in crowded conditions to alternative host plants. Thus we conducted experiments on host plant selection of neonate larvae. Similar to the adults, neonates demonstrated no significant preference between cucurbit crops (watermelon, squash, cantaloupe) and they would readily feed on leaves of any of these plants. But they do prefer cucurbits to bean leaves. If a larva had experience feeding on a particular cucurbit they also did not demonstrate any preference for that plant if offered a choice later on...it appears that any cucurbit will do. However, we also found that neonates will feed on bean leaves if forced to and experience with feeding on bean did lead to an apparent preference for bean. The question remains as to whether the larvae can complete development on a reputed non-host plant such as bean or not. Bean could be a possible deterrent crop used in a push-pull management system. In another experiment we investigated the impact of pupal burial on successful adult eclosion and emergence. We found that pupal burial did not affect adult eclosion regardless of the depth. Adult emergence from the soil surface declined with increasing soil depth. If the pupae were buried at least five centimeters under the soil surface then the adult moths did not survive. However, some moths still survived even if the pupae were buried four centimeters below the soil surface. These results suggest that cultural control techniques such as plowing might be useful in disrupting the pupal stage of this pest. However, this is not likely to be incorporated into current production practices in Hawaii where trellises, irrigation and ground covers remain in fixed positions. We also examined the preferences for late instar larvae for different pupation sites. We found that when given different choices about pupation materials, the material itself doesn’t seem to matter but larvae are attracted to dark areas in which to pupate. How this might be applied for pickleworm management needs to be further investigated. Jari Sugano consulted with several growers over the course of this project. In particular, a commercial aquaponics farm in Mililani had a reduction in pickleworm damage from 90%-5% through cultural/ sanitation practices and OMRI approved chemicals. Growers have expressed interest in the potential for essential oils. One grower tested lavender oil for pickleworm control in a small portion of their field but the plants experienced leaf burn. Thus further study needs to be conducted to evaluate the phytotoxicity of these products and perhaps synergists or adjuvants that would protect the plants but maintain the potency of the essential oils.
Publications
- Type:
Journal Articles
Status:
Under Review
Year Published:
2013
Citation:
Leiner R. and Spafford, H. 2013. Crop Protection. Oviposition preferences of pickleworm with implication for a potential push-pull cropping management approach.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2013
Citation:
Leiner, R. and Spafford, H. 2013. Florida Entomologist. Making tracks: Implications of neonate pickleworm (Diaphania nitidalis Cramer) movement for pest management.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Spafford, H. Wright, M. and Kaufman, L. Unwelcome guests in Hawaiian agriculture and natural systems. Invited Oral presentation at the 97th Pacific Branch meeting of the Entomological Society of America. Lake Tahoe, Nevada April 2013
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2011
Citation:
Leiner, R. and Spafford, H. 2011. Pickleworm in Hawaii: Prospects for Management. Abstracts of the 95th Pacific Branch Entomological Society of America meeting, Waikoloa, HI, March 2011. Pg 73-74 http://entsoc.org/PDF/Pacific/meetings/FINAL_PBESA_2011_Abstracts.pdf
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2012
Citation:
Leiner, R. and Spafford, H. 2012. Oviposition preferences of Pickleworm (Diaphania nitidalis) with implications for management by trap crops and companion planting. Entomological Society of America National Meeting, Knoxville, Tennessee November 2012.
http://esa.confex.com/esa/2012/webprogram/Paper69324.html
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: The overall aim of this research is to evaluate alternatives to synthetic insecticide spray for pickleworm pest management. As part of this work we evaluated the potential of a push-pull cropping system. Several experiments were completed that evaluated the oviposition behavior of adult pickleworm when offered different host plants at different scales. We also completed an experiment evaluating the longevity of adult moths on different liquid diets. Experiments were conducted to assess neonate larval longevity and dispersal behavior. Another aspect of this work has been to evaluate the mortality of neonate larvae to dilutions of various essential oils. Research results were reported at one national entomology conference, and two regional association conferences. PARTICIPANTS: Helen Spafford, lead researcher on the project. Jari Sugano, extension agent interacted with several growers Ron Mau, provided advice. Rosalie Leiner, studied pickleworm for her Master's degree research; employed as a graduate research assistant on the project. Erik Patnude, undergraduate student conducted directed research as part of this project. Students in the Foundations of Pest Management class also conducted research on pickleworm as part of a class project and presented their work at the CTAHR Student Research Symposium in 2012. TARGET AUDIENCES: Several growers were contacted and the results of the experiments were discussed with them enabling the research team to provide informed recommendations for alternatives to pesticide use. One grower tested an essential oil treatment on his squash plants but found that the concentration was phytotoxic. Other growers are interested in testing these solutions but further experimentation is clearly necessary before we can provide confident recommendations. PROJECT MODIFICATIONS: We have been unable to successfully recollect any of the parasitoids that were found in pickleworm larvae and so further research on the potential of these insects as biological control agents has not been undertaken. We also have not been able to successfully conduct the predator exclusion experiments and evaluate the potential predators of pickleworm eggs, larvae, and pupae as part of this research project. Instead we have focused on testing the essential oils.
Impacts
Through a series of experiments we determined that pickleworm females do seem to have preferences for different host plants but these preferences appear to change according to the scale in which the experiment is conducted. The female moths exhibited different host plant preferences when offered single leaves of host plants compared to when they were offered whole plants. Neonate larvae are able to survive for several days and move quickly across a distance comparable to normal crop row spacing. This suggests that even if adult preferences were not so labile, the neonates could move if in crowded conditions to alternative host plants. Thus, it appears at this point that a push-pull system using curcubits is not likely to work for pickleworm management. Consequently, we are advising growers to pursue alternative tactics to manage this pest, despite the recommendations in the published literature. Further experimentation on a field scale is necessary to confirm this. As an alternative, several essential oils were determined to reduce neonate survivorship through both direct contact, residual contact and vapors. Discussions with growers indicate an interest in the potential for essential oils to manage pickleworm. One grower tried using oil on his plants but experienced phytotoxicity. Thus, further experiments are necessary to determine both the phytotoxicity and the best method of application.
Publications
- No publications reported this period
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: The survey of growers was completed. Initial experiments to understand adult female oviposition preferences have been completed and further experimentation continues. A study on pupal burial has been completed. Investigation of neonate foraging preferences has been completed. PARTICIPANTS: Helen Spafford (PD) continued to direct the research activities of the project and participated actively in the experimental design and research direction. Ronald Mau (PD) continued to provide advice during the project. Jari Sugano (PD) provided advice to growers related to pickleworm management. An undergraduate technician was employed to assist with colony maintenance and to conduct the survey of growers.Rosalie Leiner, was appointed as a MS graduate student on this project in August 2010. She continued to progress with establishment and maintenance of the research colony and successfully completed several experiments. Another student, Jordie Ocenar, engaged in a Directed Research project as part of her undergraduate program. She was not employed by the project while completing a small experiment that contributed to the understanding of pickleworm development. Dr. Koon Hui Wang collaborated with Jari Sugano on the field evaluation of insecticides. TARGET AUDIENCES: Cucurbit growers on Oahu, Maui and Hawai'i were contacted as part of the survey on current management practices. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We completed the survey of cucubit growers. Pickleworm continues to be a major problem for every grower surveyed. We established that there have been growers who have ceased production of cucurbit crops due to pickleworm damage. Those growers continuing to produce cucurbits continue to manage pickleworm by spraying insecticides. There are no other methods of management being used by any of the growers surveyed. A non-replicated field trial was set up at Poamoho RS. We evaluated organically approved products such as Entrust, Bt, Beauveria bassiana, and Steinernema feltia. Entrust was the most effective product for pickleworm. Laboratory research has yielded some interesting results. In a series of oviposition preference experiments we discovered that pickleworm females do not appear to distinguish between different varieties of curcurbit. Experiments continue to evaluate preferences of adult female moths between different crop plants to ascertain whether a push-pull system could be useful for management of this pest. Due to our observation that neonate larvae are highly mobile we also conducted some experiments to evaluate the longevity of larvae without food and the feeding preferences of neonate larvae. We found that neonates could indeed survive for several days without food and were highly mobile during that time suggesting that larvae could potentially be important in the host plant selection process and consequent crop damage. Experiments on host plant selection of neonate larvae demonstrated no significant preference between cucurbit crops (watermelon, squash, canteloupe) and they would readily feed on leaves of any of these plants. But they do prefer cucurbits to bean leaves. If a larva had experience feeding on a particular cucurbit they also did not demonstrate any preference for that plant if offered a choice later on...it appears that any curcubit will do. However, we also found that neonates will feed on bean leaves if forced to and experience with feeding on bean did lead to an apparent preference for bean. The question remains as to whether the larvae can complete development on a reputed non-host plant such as bean or not. In another experiment we investigated the impact of pupal burial on successful adult eclosion and emergence. We found that pupal burial did not affect adult eclosion regardless of the depth. Adult emergence from the soil surface declined with increasing soil depth. If the pupae were buried at least five centimeters under the soil surface then the adult moths did not survive. However, some moths still survived even if the pupae were buried four centimeters below the soil surface. These results suggest that cultural control techniques such as plowing might be useful in disrupting the pupal stage of this pest. However, this is not likely to be incorporated into current production practices in Hawaii where trellises, irrigation and ground covers remain in fixed positions. Jari Sugano consulted with several growers over the past year. In particular, a commercial aquaponics farm in Mililani had a reduction in pickleworm damage from 90%-5% through cultural/ sanitation practices and OMRI approved chemicals.
Publications
- Leiner, R. and Spafford, H. 2011. Pickleworm in Hawaii: prospects for management. Pacific Branch meeting of Entomological Society of America, Waikaloa, Hawaii. March 2011.
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: A graduate assistant has been appointed to assist with the project and a colony of pickleworm has been established. Land for the monitoring has not yet become available. However, there are no direct outputs from this project as yet. PARTICIPANTS: Dr. Helen Spafford, Assistant Professor at UH Manoa has been the principle person invovled with this project as PD. She has been engaged in establishing the pickleworm colony, generating questions for the farmer survey and directing the graduate assistant hired on this project. Ms. Jari Sugano, Extension Agent, co-PI, has assisted with the selection of varieties to grow in the glasshouse for use as host plants for the pickleworm and generating questions and approach for use in the farmer survey. Prof. Ronald Mau, co-PI, has assisted with the establishment of the colony. Ms. Rosalie Leiner, Graduate Assistant, has worked on the establishment of the pickleworm colony and experimental design for the monitoring and other field experiments. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: The establishment of the colony took much longer than expected due to difficulties getting pickleworm adults to lay eggs in the laboratory. It was necessary to conduct a more thorough search of the literature to find some of the older, less accessible papers in order to obtain the information necessary to provide the right conditions for the adults to stimulate oviposition. A suitable graduate assistant was not appointed until August 2010. This has meant that the predator experiments will be delayed. Monitoring has also not begun at this point because land has not yet been acquired for this. It is anticipated that the monitoring will begin in the new year (2011).
Impacts
There are no findings, results or techniques from this project that have yet contributed to an outcome or impact.
Publications
- No publications reported this period
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