Progress 09/01/11 to 02/28/14
Outputs
Target Audience: Cucumber beetles are a pest which damages multiple crops throughout North America. In 2010, cantaloupe melon production in the United States spanned 74,000 acres and earned $346 million for melon growers. Honeydew melons, another key host, were grown on ~15,000 acres valued at ~$50 million. California produces about 60 and 80% of the cantaloupes and honeydew melons, respectively. Cucurbit crops such as melons, squash, pumpkins, and other crops including beans, sweet corn, leafy greens and peppers are prone to feeding damage. Although all cucurbits are susceptible to cucumber beetle damage, smooth-skinned melons are particularly vulnerable to this pest. Cucumber beetles primarily cause cosmetic damage to melons, thus significantly reducing yields for market ready melons. The market demands melons must be unblemished and export melons are expected to exhibit a high level of quality. This research was conducted on honeydew melons which are primarily grown in California within the United States. Melon growers of California and organic production growers are greatly interested in this research, as organic production is significantly hindered by this pest. Grower groups and agrichemical companies are also interested in the findings of this research. This research was conducted in cooperation with large organic production melon growers in Yolo Co., California. Rachael Long, a CE Advisor for Yolo Co., was involved in this project and was able to keep growers apprised of our findings directly. Our results have been shared with central California melon growers, who have endured the most severe cucumber beetle infestations. During the course of this research, presentations have been made to grower groups at production and IPM meetings. Additionally, our results were presented to the scientific community at the Entomological Society of America meeting at the Vegetable Crops symposium in November 2013. The results of this research will be made available to a broader base of interested parties after they are incorporated into the University of California Pest Management Guidelines for melons. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One individual who coordinated much of the research for this project was trained. She has a B.S. degree in Biotechnology and has worked for 2 years on this project. She is now attempting enter graduate school with an Entomology/Integrated Pest Management focus as one of her objectives. Two undergraduate students also worked on this project and they have interests in Entomology for careers. How have the results been disseminated to communities of interest? Oral presentations, web site updates, and one-on-one interactions have all been used. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Studies on cultural, biological, host plant resistance, and chemical tactics were conducted for this research project. The tachinid fly, Celatoria setosa, is known to parasitize striped cucumber beetles and potentially, spotted cucumber beetles. Preliminary studies conducted in 2009 showed parasitism levels up to 60% in striped beetles, with parasitism incidence peaking in the fall. Both subspecies (spotted and striped) of cucumber beetles were collected from June through November of 2012 and 2013. Adult beetles were obtained from melons grown on organic farms in Yolo Co., CA and sustained in the laboratory for several weeks on melon foliage. Spotted cucumber beetles showed no incidence of parasitism. Striped beetles showed parasitism up to 15%, with parasitism peaking early (July) then declining during the fall, opposite of what was found in initial studies. In 2012, low beetle populations yielded low numbers which made theresults difficult to interpret. In 2013, a new method was developed to collect beetles under individual melons and consistently yielded 10 times the number of striped beetles when compared with the sweep net method previously used. Four locations/farms were sampled. This is not surprising since striped cucumber beetles tend to spend most of their time under vines and melons, where they cause the most damage and economic concern. The collection method used in 2013 was similar to that used in the 2009 studies so results should be comparable, although there is concern that this location under melons may offer protection from parasitism. Twenty years ago, McCreight (USDA-ARS) conducted studies with an experimental line of melons which exhibited some resistance to cucumber beetle feeding in comparison to commercial honeydew melons (the goal of these studies was another pest but observations were made on cucumber beetle damage). This experimental line was propagated in the greenhouse at UC-Davis and seedlings were transplanted with a commercial variety of honeydew. Plants of these two lines were observed for evidence of beetle feeding in replicated plots. Cucumber beetle numbers, species and levels of fruit damage were monitored over a six week period during the summer of 2012 and 2013. Beetle numbers showed between 21%-47% preference for the experimental line over the commercial line during four of the six weeks. These results suggest the experimental line of melons could be further investigated in functioning as a trap crop in the future. This variety has roughly twice the number of flowers and a slightly longer flowering period than commercial varieties we tested. Therefore this experimental line may provide a more attractive food source for cucumber beetles, rather than current commercial varieties. Regardless of population numbers, growers frequently treat melon fields at the first signs of beetle infestation. Field plots were designed to establish a treatment threshold for melon damage and to develop a cucumber beetle monitoring plan on honeydew melons. Insecticides were used on these plots to achieve beetle management levels. Control levels ranged from no control (0%), partial control (50%-75%) and virtually complete control (~100%). Results showed we were able to achieve these reduction goals and attained an average of 90% reduction for the “complete control” plots. Treatments began at the early fruiting stage and were maintained approximately 6 weeks in 2012 and 2013. Cucumber beetle feeding primarily causes cosmetic damage, affecting melon surfaces rather than crop yield. Regardless of treatment used, the majority of feeding damage occurred on the melon abaxial surface and this was at unacceptable levels. This study showed damage on the upper surface of the melons was positively impacted in association with beetle populations and management. The habit of the cucumber beetles (primarily the striped species) to infest, reside, and feed under the developing melon is problematic. This impedes the ability to control the beetles with any management t approach including foliar insecticides, biological, etc. Through this process, kairomone-baited yellow sticky traps appeared to be the most sensitive monitoring tool to determine population densities. Field plots were set up and managed to investigate the efficacy of various organic and reduced risk insecticides for cucumber beetle control. Several treatments were applied to melon seedlings and exposed to both subspecies of cucumber beetles. Feeding damage and plant vigor was monitored for several weeks. The beetles primarily fed on seedling stems at soil-level. Compared to untreated seedlings, Thiamethoxam seed treatment produced larger seedlings with double the plant stand compared with untreated plots. As the growing season progressed, the efficacy two organic products was compared with carbaryl, pyrethroid and indoxicarb insecticides in replicated field plots Surround® utilizes kaolin clay based particle film technology to create a protective barrier on the plant and a combination of Grandevo® + Cedar Gard® was also tested. On more mature melons, Grandevo® + Cedar Gard® demonstrated short-term control capabilities. The most effective pest control was provided by the pyrethroid and followed by the carbaryl. Cidetrak®D is a gustatory stimulant derived from cucurbit bitters, obtained from buffalo gourd. Cidetrak ®D is a natural compound with no insecticidal properties and must be combined with a lower rate of an insecticide to achieve pest control. When combined with an insecticide, it is intended to enhance efficacy by stimulating insect feeding of applied insecticides. Currently, the standard is for Cidetrak®D to be combined with carbaryl at 1/10th of the suggested label rate. However, carbaryl is a carbamate insecticide with several potential drawbacks. A laboratory bioassay was conducted to investigate whether newer reduced risk insecticides could replace carbaryl usage. Ten reduced risk and biological insecticides were applied to melon leaves, in combination with and without Cidetrak®D. Spotted cucumber beetles fed on the treated leaves and beetle mortality was assessed after three days. Cidetrak®D combined with Imidacloprid showed the greatest correlation as a gustatory stimulant. The addition of Cidetrak®D yielded high beetle mortality, and the absence of Cidetrak®D caused low beetle mortality.
Publications
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Progress 09/01/12 to 08/31/13
Outputs
Target Audience: The target audiences for this project are varied. Clearly, melon growers of California are interested in this research. The research was conducted on honeydew melons which are primarily grown in California within the United States. The smooth-skinned melons are particularly prone to damage from cucumber beetles. However, this insect, cucumber beetle, is a pest of numerous crops. All cucurbits are potentially affected including all melons types, pumpkins, squash, etc. In addition, organic production is hindered greatly by cucumber beetles. Feeding by the adults on leafy greens, peppers, beans, sweet corn, etc. is a significant problem. The beetles inflict cosmetic damage to produce. The results have been delivered to melon growers in central California, the most affected area by cucumber beetles. The research was actually conducted, in part, with the larger melon growers (organic production) in Yolo Co. thus this facilitated information delivery. Rachael Long, a CE Advisor for Yolo Co., was involved in this project and acted as a liaison with the participating growers. Presentations have been made to grower groups at production/IPM meetings. Commercial entities, i.e., agrichemical companies, were apprised of the results as well. Results were presented to a scientific audience in November 2013 at the Entomological Society of America meeting at the Vegetable Crops symposium. Finally, the applicable results will be incorporated into the Univ. of California Pest Management Guidelines for melons at the time of the next revision. Results have not been as effectively delivered to the organic agriculture / production industry. At this initiation of this project, that was not a stated or primary goal but the applicability of these results to that industry is obvious. Additional efforts will be made to address that clientele group. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One individual who coordinated much of the research for this project was trained. She has a B.S. degree in Biotechnology and has worked for 2 years on this project. She is now attempting enter graduate school with an Entomology/Integrated Pest Management focus as one of her objectives. Two undergraduate students also worked on this project and they have interests in Entomology for careers. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals? This project ends in Feb. 2014 (orginally Sept. 2013 but an extension was obtained). We were collecting data from the field studies until Nov. 2013. The last few months will involve data summarization, analyses, and publication writing.
Impacts
What was accomplished under these goals?
Cucumber beetle populations (both the striped and spotted subspecies) were sampled from commercial melon fields at four locations in Yolo Co., CA from July to November. Adults were taken to the laboratory and held on melon foliage so the incidence of parasitism by the tachind fly, Celatoria setosa, could be quantified. Preliminary studies in 2009 showed levels up to 60%. In 2013, parasitism ranged up to 15% of the striped cucumber beetles and the spotted cucumber beetles were not parasitized. The trend was for higher values in the early part of the season declining in the fall. This was the opposite trend seen in 2009 in the preliminary study. The gustatory stimulant, Cidetrak® D, was evaluated in previous studies. This compound/product, derived from cucurbit bitters (natural component of buffalo gourd), has no insecticidal properties of its own so it must be combined with a low dose of an insecticide to control cucumber beetles. The standard for this is carbaryl at 1/10 the label rate. Carbaryl is a carbamate insecticide with several potential drawbacks. Thus I was interested if some of the newer reduced risk insecticides could fill this role. Ten different biological and reduced risk conventional insecticides were evaluated in a laboratory bioassay. These were tested on spotted cucumber beetles with and without the addition of Cidetrak. Imidacloprid showed the greatest response from the addition of Cidetrak, i.e., low beetle mortality without and increased mortality with Cidetrak. The efficacy of other reduced risk and biological insecticides was evaluated against both cucumber beetle subspecies. On seedling melons, Thiamethoxam seed treatment resulted in twice the plant stand compared with the untreated seed. In addition, the resulting melon seedlings were larger with the seed treatment. This damage was primary from the beetles feeding on the seedling stems at soil-level. Later in the season, the efficacy of a pyrethroid, carbaryl, and indoxacarb insecticides was compared with that of two organic products, Surround® particle film technology (active ingredient of kaolin clay) and Grandevo® + Cedar Gard®. The best control was from the pyrethroid followed by carbaryl. Some short-term control was seen with the Grandevo+Cedar Gard. The final objective dealt with the treatment threshold from cucumber beetles on honeydew melons. Growers now often treat at first signs of beetle infestation. Plots were set-up and managed with insecticides to attempt to provide complete beetle control (as much as possible), partial control and no control of the high population occurring at this field site. Treatments were started at the early fruiting stage and maintained for about 6 weeks. Melons were harvested and the damage rated. Beetle populations were effectively manipulated. As anticipated, melon yields were unaffected by beetle populations. The feeding by the cucumber beetles primarily affects quality, i.e., cosmetic damage. Melon damage on the upper surface was positively impacted and associated with beetle populations. Damage on the abaxial surface was universally high and at an unacceptable level.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Godfrey, Larry D., Rachael F. Long, and Amy Bell. 2013. Refined Management of Cucumber Beetles (Diabrotica sp. and Acalymma sp.) in Central California Melons: Implications for Organic Vegetable Production, presentation at Annual meeting of Entomological Society of America, November 13, 2013.
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Progress 09/01/11 to 08/31/12
Outputs
OUTPUTS: This project is partially through the first field season and studies are very much in-progress. During the winter/spring, an outstanding employee was hired to coordinate the studies. Research this summer has progressed well but data have not been summarized yet and field studies are still ongoing. Considerable effort was made, in cooperation with Rachael Long based in Yolo Co., to examine the role of alfalfa management as a cultural control tool for cucumber beetles in melons. Studies were done with two cooperating melon/alfalfa growers in Yolo County. Alfalfa cutting procedures/schedules were manipulated and the resulting beetle densities in adjacent melon fields were quantified. Data were collected in the melon fields at various distances from the alfalfa field to allow for a spatial aspect. A study is ongoing to examine the relationship between cucumber beetle numbers from kairomone-baited sticky traps and visual counts, and honeydew melon yield and quality. Melon growth and beetle numbers have been adequate so the results should be usable. A study was added to facilitate this objective that being confining various numbers of spotted cucumber beetles in screened cages and the resulting melon damage observed. Laboratory and field studies were done to examine the possible levels of resistance of an experimental melon line compared with a commercial honeydew melon line. The experimental line was found to exhibit some resistance to cucumber beetle infestation and damage in studies 20+ years ago by McCreight (USDA-ARS). After increasing the seed in the greenhouse, these two cultivars were grown in field plots and the cucumber beetle numbers and species and fruit damage were monitored. Finally, attempts were made to collect striped cucumber beetles for quantification of the levels of parasitism by a Tachinid fly. This natural enemy was shown to occur in central California melon fields in some earlier studies (2007-2009). In 2012, the striped species of the cucumber beetle was at very low levels and obtaining an adequate number of beetles for this study was impossible. Data were collected on the moderate number of beetles obtained. Results have not reached the stage for dissemination yet. The grower cooperators we worked with will be informed of the results but doing this on a broader basis is premature. PARTICIPANTS: Research was done on two grower collaborator ranches and they have been advised of the ongoing results and will be given the annual summary. In addition, beetle collections (searching for striped cucumber beetles) were done on four to six other melon locations in central California. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
I am optimistic that outcomes/impacts as a change in knowledge, actions, or conditions will occur from this project but this will result at the conclusion of the two-year study, especially after the 2 field seasons. As we are still in-progress of the first field season and data have not yet been summarized/interpreted, therefore outcomes and impacts will not possible yet.
Publications
- No publications reported this period
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