Final report for ONE19-345
Oriental beetle grubs feed on blueberry roots and can add severe stress on mature plants and kill younger plants. Blueberry growers use ground applied imidacloprid insecticide during June to control young grubs. This material has long lasting effects. Many growers refuse to use it because of their observations that it inhibits bee activity and pollination during the following spring. The initial goals of this project were to take previous research on 2 alternative controls: 1) mating disruption of Oriental beetle, and 2) to add initial results from small trials with a B.t. compound; and to demonstrate these practices on a large scale in cooperation with 3 commercial, wholesale market blueberry operations. We knew that from previous work in small (3-4 A plots), mating disruption was a viable commercial alternative to the use of imidacloprid (a neonicotinoid) insecticide.
Benefits & Impacts - Mating disruption material costs are higher than insecticide use, and also require additional labor to place the dispensers ($50.30/A material + about $2.50/A labor) vs $24.50/A material and about the same for labor for imidacloprid. The Bt product is comparatively very expensive and is not yet marketed in large quantities. However, replacing neonicotinoid insecticide use would still control beetle grubs and inhibit root feeding, while mitigating potential negative effects on honey bees and pollination activity. Use of mating disruption in other crops has shown that when used over consecutive years, resulting control can actually be better than with insecticides alone since the pest population decreases over time. Grower familiarity with the mating disruption dispensers was a challenge due to the distributor's limited marketing ability and competition with standard insecticides.
Our basic methods were to demonstrate mating disruption use on 3 commercial farms in large plots. Participating growers helped install the dispensers, along with our help. Because of access to the B.t. product and difficulties with the Covid pandemic, the B.t. treatments were not included. Grub populations and adult presence were collected over a 3 year period (2019-2021), and compared between treatments. Grub populations were highly variable between farms, but on average, numerically decreased over the 3 year period. While we could not statistically separate results, the population decrease mirrored previous results in research plots, and demonstrated the effectiveness of the practice. The results were shared at professional meetings, and 'how to' practices were shared in 2 annual grower meetings, several update meetings, and newsletters.
This project seeks to demonstrate how 2 alternative management strategies can be used in commercial blueberry production for Oriental beetle grub control. We will demonstrate the effectiveness of mating disruption used alone over 1 and 2 year periods. We will also demonstrate the effectiveness of the Bt, ‘beetleGONE!’ product, used alone and in combination with mating disruption treatments. This is a cooperative on-farm project, where growers will be making the applications, while we will be monitoring treatment performance, and reporting back to the participants and other commercial growers. Our objectives include the growers experiencing the results for 2 years, talking to other growers about the experience, and making presentations (Variety Farms) on their site. Successful completion of our objectives should result in further use of sustainable practices, and better control of Oriental beetle, resulting in lower grub populations and improved plant health. The project should benefit both farmers and beekeepers, since it will remove a major insecticide application that has negative effects on bees. Growers who presently don’t treat for Oriental beetle because of adverse bee and pollination issues, should change their practices and treat, knowing that their treatments will not affect pollination and improve plant health.
New Jersey is a leading producer of highbush blueberries, grown on 10,000 acres. Most of the production is on the sandy, porous soils in and around the Pinelands National Reserve, an ecologically sensitive area. Blueberries are a high value crop with plantings that average 1,450 plants per acre. NJ production ranks 6th in the US, and in 2017 was valued at $83.4 million (NJDA/NASS 2018). Good production practices can yield 12,000 to 14,000 lb/A, worth $18,000+/A. Full production can actually yield over $20,000/A, depending on market price and yield (Galinato and Gallardo, 2015). The Oriental beetle, Anomala orientalis, (OB) is the most abundant grub pest in New Jersey blueberries, and is considered by growers as one of the most important pests of blueberries in the state. Feeding damage caused by OB grubs can result in complete destruction of the root system, often killing entire sections of fields. Infested bushes show reduced vigor and support fewer berries, compared with healthy bushes.
Limited options are currently available to manage OB populations in blueberries. The neonicotinoid, imidacloprid is the only insecticide registered in blueberries for grub control. Imidacloprid requires precise application timing, has no efficacy against older larvae, is highly leachable, and may disrupt pollination. The difficulties with application timing have discouraged many growers from treating for OB. Applications are applied in early June during egg laying. This is the same period when blueberry bushes are closing in on the rows from fruit weight, making it difficult to use ground sprayers. Many growers do not treat for grubs because of the possible negative hold-over effects of imidacloprid residues in the flowers, and the perceived negative effects on pollination and fruit yield. As a neonicotinoid insecticide the negative effects of these compounds on bees have been well documented (Johnson, 2015; Williams et.al., 2015; Zhu et.al., 2017). Also, having a single control method raises resistance management concerns. Because blueberries are grown in an ecologically-sensitive area, it’s unlikely that additional soil applied insecticides will ever be registered for this use.
The blueberry IPM program monitors adult Oriental beetles (OB) with pheromone traps to help time insecticide applications. During the past 3 years our trap counts have increased compared to previous years. During our September soil fertility sampling, several grubs were found in the soil probe, suggesting that high populations were present in the fields. Therefore, we did a grub survey during the fall of 2018. We sampled roots from 6 bushes in each of 230 fields. Our results showed that OB grubs were present and feeding on roots in 64% of the samples. In some cases there were over 6-10 grubs per root system. This demonstrates the urgency of growers taking the steps to control this pest.
Recent advances in alternative controls shows promise in addressing the OB problem. Mating disruption dispensers (AgBio) gained EPA registration in 2012 (EPA, 2012) for hand-applied plastic dispensers. In 2013 a new strain of Bacillus thuringiensis subsp. Galleriae targeting several beetle species, attained an EPA label as ‘beetleGONE!’
We determined that 0.05 g of the oriental beetle pheromone, at 20 dispensers per acre was sufficient to provide effective oriental beetle mating disruption in blueberries (Rodriguez-Saona et.al.,2009). Recent work with a formulation of Bacillus thuringiensis subsp. Galleriae, has produced a new commercial insecticide effective for Scarab beetle grubs, ‘Phyllom beetleGONE!’(EPA, 2013). These products have been tested in small plots and are commercially available. Neither product is in wide-scale use at the present time. Mating disruption for Oriental beetle has been shown to be effective, while avoiding the difficulties of spray timing and the negative impacts of neonicotinoid use. The use of Bt Galleriae has been shown to be effective for Oriental beetle and similar species (Asana et.al, 2003), and its use in experimental plots in NJ appears promising (Rodriguez-Saona, 2014 unpubl.).
We have a number of years’ experience validating the efficacy of several forms of OB mating disruption (MD) dispensers (Rodriguez et.al., 2010; 2014). We know how the system works, how to place them and how many dispensers to use. This work has been supported by several EPA and IR-4 Biopesticide grants. Initial work in NJ with ‘Phyllom beetleGONE!’ showed promising results in 2014, but the data suggested that efficacy may be improved in a combination with another control such as mating disruption. Work in other states and crops has shown commercial efficacy on several Scarab species (Schwartau, IR-4, 2014).
Growers have overlooked the serious impact Oriental beetle causes. This is changing since populations have increased and grub infestations are now common. In fact, growers are asking us what other control options there are, besides the traditional imidacloprid soil sprays. Concurrent to OB population increases and resulting grub infestations, beekeepers are experiencing serious colony collapse associated with blueberry pollination services. Among other consequences, this is causing a degree of friction between beekeepers and blueberry growers, is resulting in hive loss for the beekeepers and increases in hive rental for blueberry growers. For a medium size blueberry farm of about 250 acres, the hive rental increase alone represents $10,000 to $15,000.
Therefore there are several aspects in the Oriental beetle problem and our approach that are new.
- Oriental beetle populations have increased over the last 3 years as shown by our adult pheromone trap records. Peak captures during the last 3 years have ranged from 10,000 to 15,000 beetles per trap/week, whereas previous year peak captures were 5,000-6,000 adults per trap.
- Most growers have neglected treating for Oriental beetles, given difficulties with application timing and bee toxicity issues.
- High adult populations have translated to widespread larval/grub infestations, which affect bush health and yield.
- New practices are available. Mating disruption needs to be demonstrated by the growers on a commercial scale, and a new Bt selection is ideally suited to be folded into an on-farm alternative control system.
Successful commercial use of these 2 practices will reduce OB populations without the problems associated with spray timing, and the negative effects of neonicotinoid use, as well as taking 1 more factor ‘off the table’ that has negatively affected bee health. The growers and we have collaboratively arrived at 3 demonstration sites that represent NJ blueberry production. Total acreage under the alternative practices will range from 12 to 250 acres per farm, and include large commercial production as well as small organic fields.
Asano, S. Yamashita, C, Lizuka, T, Takeuchi, K, Yamanaka, S, Cerf, D. and Yamamoto, T. 2003. A strain of Bacillus thuringiensis subsp. Galleriae containing a novel cry8 gene highly toxic to Anomala cuprea (Coleoptera: Scarabaeidae), BioControl 28:191-196.
Denson, C. 2018. Oriental beetle, still a hidden issue. Blueberry Open House. Hammonton, NJ. Rutgers
Cooperative Extension Annual Blueberry Grower Meeting, February 19, 2019
EPA, Office of Pesticide Programs. 2012. Reg No. 68253-1. https://www3.epa.gov/pesticides/chem_search/ppls/068253-00001-20120305.pdf
EPA Federal Register. 2013. Issuance of two experimental use permits. Document citation 78 FR 40737. Doc. No. 2013-16317.
Galinato, S.P., and Gallardo, R. K. 2015. 2015 Cost estimates of establishing and producing conventional highbush blueberries in western Washington. Washington State Univ. Extension. TB36.
Johnson, R. 2015. Honey Bee Toxicology. Annu. Rev. Entomol. 2015. 60:415-434. NJDA/NASS. 2018. NJDA 2018 annual report & agricultural statistics. www.nass.usda.gov.
OMAFRA. 2003. Mating disruption for management of insect pests. Ontario Ministry of Agriculture, Food and
Rodriguez-Saona, C., D.F. Polk, and J.D. Barry. 2009. Optimization of pheromone rates for effective mating disruption of oriental beetle (Coleoptera: Scarabaeidae) in commercial blueberries. J. Econ. Entomol. 102: 659-669.
Rodriguez-Saona, C.R., Polk, D., Holdcraft, R., and Koppenhöfer, A.M. 2014. Long-term evaluation of field-wide oriental beetle (Col., Scarabaeidae) mating disruption in blueberries using female-mimic pheromone lures. J. Appl. Entomol. 138: 120-132.
Rodriguez-Saona, 2014 unpubl. Preliminary trials with ‘beetleGONE!’ Schartau, K. 2014. IR-4 Food Use Workshop Presentation.
Williams, G.R., Troxler A, Retschnig, G, Roth, K, Yanez O, Shutler, D, Neumann, P, and Gauthier, L. 2015. Neonicotinoid pesticides severely affect honey bee queens. Nature Scientific Reports. 5: 14621, DOI:10.1038/srep14621.
Zhu, Y.C, Yao, J, Adamczyk, J, and Luttrell, R. 2017. Feeding toxicity and impact of imidacloprid formulation and mixtures with six representative pesticides at residue concentration on honey bee physiology (Apis mellifera). PLos One 12(6): e0178421, PMC5462352, PMID: 28591204. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5462352/
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- (Educator and Researcher)
We completed the initial planning with 3 commercial blueberry growers in late 2019 and the winter of 2020. This project lasted 2 years since: 1) The Oriental beetle life cycle lasts for an entire year and grub populations were measured at the end of the year; 2) Grant funding for the 1st year did not start until well after OB management was finished for the 2019 season; and 3) Mating disruption practices show greater effectiveness in decreasing an insect population when done over multiple years, while lowering the population during treatment years (OMAFRA, 2003). Mating disruption also works better when used over large acreages or entire farms. This is why we utilized virtually entire farm sites for this work. Our farms ranged from 12 to 250 acres. Each site was divided into 4 treatment areas, of unequal size. This gave us sufficient acreage for commercial demonstration and ease of grower management, and also 4 treatments and 3 replications for data analysis and publication. The treatment/demonstrations on each farm site were intended to be:
- Mating disruption used alone.
- Mating disruption combined with 2 ground applications of ‘beetleGONE!’ Bt biological insecticide.
- Two ground applications of ‘beetleGONE!’ insecticide used alone. (This was later deleted for reasons given below)
- Untreated control
Data Collection: Measuring Adult Activity - In each treatment plot we placed pheromone traps and weekly monitored adult Oriental beetles starting at first emergence the last week of May. We placed 2 Japanese beetle sex pheromone traps (Trecé, Adair, OK) baited with 0.3 μg of oriental beetle sex pheromone (Total 2 traps per plot, 4 plots, 3 replicates = 24 traps). These lures mimic female calling, and therefore create an accurate measurement of the adult male activity, responding to virgin females over a short distance, while not drawing males from outside the plot area. Traps were placed in the plot centers and monitored weekly throughout the total adult emergence period. Trap records reflect the relative populations within each treatment area. Adult trap capture is a measurement of MD effectiveness, producing very low trap counts. Trap counts in mating disruption plots are used to help assess the effectiveness of the mating disruption treatments, since the virgin female ‘mimic’ cannot be found by the males, traps captures should be almost shut down. However, lack of adult trap capture is only one measurement of treatment effectiveness. The actual damaging stage also has to be reduced. Therefore we sampled for both adult and larval populations in all treatment and check areas.
Measuring Larval/Grub populations – Soil texture in the commercial blueberry production areas in southern NJ is composed largely of acidic, medium to coarse textured sands, and accompanied with residual high organic content. Some are underlaid with thin clay layers. Therefore the water holding capacity of these soils is low. Blueberries have a shallow root system, which when combined with the soil characteristics, requires frequent irrigation. Therefor soils are often moist, easy to dig, and easily fall away from the roots. Oriental beetle oviposition starts in late May to early June and lasts through adult activity. By mid-July the first larvae are reaching the largest 3rd instar stage, and by late August to early September all larvae are 3rd instar. Larvae then overwinter in this stage around and just under the root system. Therefore we measured larval infestation levels during November and December. We used a 6 bush sample unit, using 3 sample sites per treatment or 3 samples per plot, 4 plots, 3 replicates = 36, 6 bush samples (216 per bush/soil and root exams). At each sample site 50% of the root system was undercut on 1 side of the bush parallel to the row, and soil removed, examined and sieved for larvae/grubs. The root system remains intact, but the soil can be removed with minimal damage, since the bush is dormant by this time. After examination the soil is replaced and tamped down.
All adult activity and larval assessments were done each year (2020 and 2021). We evaluated differences in population density between the treatments and between years. Since OB has only 1 generation per year, larval density should decrease between years 1 and 2 in the untreated check and if not influenced by other factors. Trap count levels or adult activity in the check (UTC) plot may increase or decrease between the 2 years, but trap counts in any mating disruption plot should remain extremely low during both years.
This work was designed as randomized complete block with 4 treatments outlined above (later emended), and replicated on 3 different farms, with farms used as the block. Data consisting of numbers of adults per trap, and numbers of grubs per 6 plants were analyzed using ANOVA, followed by LSD tests for mean differences. Data was log transformed if needed. These are similar methods as used in previous work (Rodriguez-Saona et.al, 2009, 2014), and in our Oriental beetle grub survey done in 2018 (Denson, 2018).
Field Work -
We evaluated pretreatments Oriental beetle levels during 2019 and grub levels during the fall of 2020 and 2021. We GPS located each 6 bush sample site with the mobile app "Mapit" GIS to help in relocating the same sites during the following season.
In spring of 2020, we met with the three collaborating growers to discuss how the layout of the MD tabs and the ‘beetleGone!’ would proceed. At Farm A the grower treated 180 acres with mating disruption, on Farm B - 30 acres, and on Farm C - 17 acres of MD. The plot layouts are displayed in Figure 1, where the green shading represents the acreage under mating disruption.
Participating growers were asked how they felt about putting the MD dispensers/tabs out, and all 3 growers learned the application system and applied the product during early May. At each site location we also placed Oriental Beetle (OB) traps to monitor adult populations. Trap count numbers were assessed weekly starting the 1st week in June.
Changes to Methods 2020 and 2021
We originally planned to include a treatment of beetleGone! (Baciillus thuringiensis subsp. galleriae, Strain SDS-502. However, multiple factors led us not to include this treatment.
- The company did not return a favorable price for the product to be used in the project.
- Covid-19 policies made it very difficult to add a treatment which would have required additional contact with clientele/participating growers in order to get the treatment applied.
- Investigations on the advertised retail price and the rate which needed to be used meant that the ultimate grower cost would have been between 6.6 to just over 13 times the cost of mating disruption, which is already 2.5 times the per acre cost of the chemical insecticide (imidacloprid) treatment.
Therefore the planned beetleGone! + MD plots in effect were absorbed into the mating disruption treatments, and the beetleGone! only was an additional intreated plot.
Original Timetable: (This was adhered to except as noted above), Fact Sheet being written.
March, April 2019 - Plan project with growers. Rutgers IPM and Growers
Year 1 Year 2
Initial pre-treatment assessment Nov., Dec. 2019 Nov., Dec. 2020
for larval densities. (Rutgers) (1st Yr Post Trt)
*Nov., Dec. 2021
(2nd Yr Post Trt)
Divide farm sites into March 2019 Done once March 2019
(Collaborative effort between
Rutgers and Growers)
Assess adult populations - May – August 2020 May – August 2021
Grower Meeting & Demonstrations May 2020 May 2021
Instructional workshop May 2020 May 2021
Grower Newsletters April – Aug, 2020 April – Aug, 2021
Apply Mating Disruption, May 2020 May 2021
Place Adult traps
Apply Bt biological insecticide Late May, and June, 2020 Late May, and June, 2021
(Rutgers and Growers)
Monitor and collect adult data Late May – August, 2020 Late May – August, 2021
Collect pesticide use records Sept. 2020-Nov. 2020 Sept. 2021-Nov. 2021
(Rutgers and Growers)
Data Analyses Jan. 2021 *Dec. 2021
Blueberry Open House Feb. 2021 *Feb. 2022
(Rutgers and a participating grower)
Fact Sheet --- *Jan.-Feb. 2022 *Activities marked may occur after grant funding expires, but will not require further grant funding to complete.
During the fall of 2019, we met with the three farmer collaborators to initiate grub counts. Six to eleven fields were sampled for grubs at each site to have an idea where we were going to place our 4 treatments. We examined 150 individual bushes by excavating and sieving the soil from 50% of the root area from each individual bush, then replacing and tamping down the soil. Our counts verified the significance of Oriental beetle grub populations, with an average of over 1.3 grubs per 6 bushes. This was done at the start of dormancy in order to minimize the impact on the plants. Based on the data collected, we divided the farms sites into individual treatment areas and sampling locations for the 2020 and 2021 seasons. A meeting was arranged with the supplier for the mating disruption dispensers to verify the supplies we need for the 2020 and 2021 seasons.
The effectiveness of the mating disruption treatments was measured by 2 metrics: 1) trap counts of adult male beetles, and 2) populations of live grubs found feeding on blueberry bush root systems. It is common with other pests for mating disruption to have a more pronounced effect over multiple years of treatment compared to only 1 year of treatment. The data that follows summarizes the oriental beetle populations found in the untreated control (UTC) plots compared to the combined mating disruption (MD) plots over the 2 year period.
Trap counts measure the theoretical effect of a synthetic female calling to the males with a pheromone plume. If the mating disruption is successful, then one measurement of success is that the male beetles will not find the pheromone trap, and traps should be close to being shut down with few to "0" adults found in the traps. Figure 2 shows the pheromone trap comparison between the UTC and MD plots after 2 years of mating disruption treatments. Figure 3 shows all farm averages during the pre treatment year compared to the mating disruption plots after 1 year of treatment. By measurement of adult populations found in the pheromone traps, the mating disruption indicated a reduced population of adults in the mating disruption plots
Grub counts were compared in each plot across the 3 farm replicates. Actual grub populations varied between farms (Figure 4). Between 2019 to 2021, the overall grub populations showed a decrease over both the mating disruption treatment and the non treated control fields. The percent reduction in overall grub populations was slightly greater in the mating disruption treatment, but not statistically different.
Collaborating growers accepted the new technology, organized their labor and made hand-applied applications of the mating disruption dispensers as needed.
Adult trap capture data demonstrated that mating disruption worked in shutting down males locating females, thus a key marker in mating disruption success. The seasonal average (12 week counts) from all mating disruption plots after 2 years was significantly less or close to "0" - average of 19.5, compared to the untreated control which had a peak trap capture of over 4,000 beetles per trap, with an average of 894 (see Figure 2). Trap shutdown is the first and easiest check for the success of mating disruption, and therefore should be a standard recommendation for any grower who uses this control method.
Grub populations as measured in the 6 bush samples varied greatly from farm to farm, and were initially higher in the chosen mating disruption plots. However populations in both the UTC and the mating disruption plots decreased by 2021, and on 2 of the 3 farms the percent decrease was numerically, but not statistically greater in the mating disruption plots. The unexpected, but not totally surprising result was that grub population declined in both the treated (MD) and untreated acreage. This is likely due to the fact that the mating disrupted areas of the farm sites represented the majority of the acreage. Therefore over a 2 year period, the total beetle population was reduced farm-wide, providing a lower population to infest the untreated acreage. Since the per acre mating disruption cost is more than standard insecticide use, applying the practice to the majority but not all a farm's acreage can be a cost saving and bring the cost closer in line with insecticide use.
The results, along with previous work, support the recommendation of using mating disruption over wide areas but not necessarily entire farms, and over multiple years, to achieve population reduction.
Education & Outreach Activities and Participation Summary
Participating grower consultations - Each of the 3 collaborating growers was visited once per week starting in mid-April through late August for a total of 36 visits for each grower or 108 total consultations. Due to the pandemic, much of the actual grower communication was by phone and not in person.
Newsletter/Web Blog articles - Oriental beetle information was covered in 6 articles in 2 newsletter/blog posts. Total blog post "reads" for the season totaled 92,626 during the growing season.
Organized clientele/grower educational meetings - Both live and online (Covid protocol) meetings were conducted and included 319 participants, with 1,580 distributed recordings.
Individual Grower Meetings:
“Oriental Beetle – Still A Hidden Issue.” Blueberry Open House. 03/19/19. 96 blueberry growers.
“Oriental Beetle – Still A Hidden Issue Take 2.” Blueberry Open House. 03/09/20. 85 blueberry growers.
“Update to Oriental Beetle – Still A Hidden Issue in NJ Blueberry Production.” Blueberry Open House. 03/18/21. 78 Blueberry growers.
“IPM Update and Planning Oriental Beetle Control with Mating Disruption.” Atlantic and Burlington County Blueberry Grower Twilight Update Meeting. 03/28/19. 60 blueberry growers.
“Planning a Commercial Oriental Beetle Mating Disruption Demonstration in NJ Commercial Blueberries.” Cumberland-Shenandoah Workers Conference. 12/06/19. 25 extension and research professionals.
“Update on a Commercial Demonstration of Oriental Beetle Mating Disruption in Blueberries.” Cumberland-Shenandoah Workers Conference. 12/03/20. 41 extension and research professionals.
Referenced article (pre funding) given to growers who wished to access the AgBio website:http://www.agbio-inc.com/oriental-beetle-matingdisruption.html
- Participating growers learned how to apply mating disruption dispensers.
- Participating growers saw how an alternative control (mating disruption) could work on their farms.
- All NJ blueberry growers were shown how mating disruption works.
Quotes from various growers:
“This mating disruption is great. It’s easy to do and works” From a PYO grower in central New Jersey who applied mating disruption over entire acreage.
“Easy to apply and we can do this, but where do I get it?” From a wholesale grower in Hammonton, NJ.
“We are still using it (mating disruption) on our organic acreage.” From a wholesale grower in Hammonton, NJ.
Commercial blueberry growers have requested alternatives to the use of the neonicotinoid insecticide imidacloprid (Admire), for several years. Many growers refuse to use this ground applied insecticide for Oriental beetle grub control, since they state an observation of decreased pollination during the year following application. After demonstrations with mating disruption at least 1 additional grower used the practice on 100 acres of commercial production. The mating disruption product is perceived by most growers as "hard to get", since the one company which supplies the product has no sales or distribution network within easy access. However, recent communication with an additional commercial pheromone company has shown promise of a second product coming to market that will include a sales network with easy access to growers
Challenges with this type of work include :
- Replicate farms need similar pest pressure among the various treatments, with bushes of similar age, and under the same general management.
- Demonstration plots need to be large enough to see results and be of uniform shape (not long narrow fields), but rather more square, or rectangular.
This project broke new ground in that mating disruption for Oriental beetle, while having been proven in small 3-4 acre plots, had not been demonstrated in large commercial plantings where pest pressure could significantly vary within and between plots. The fact that the grub population declined in all plots, including the non treated control over the 2 year period is most likely due to the decline in the beetle population in the largest plot, which was disrupted. Therefor, grower use of mating disruption is likely to be successful even if practiced on partial acreage, as long as the majority of the acreage is treated, thereby decreasing the pest population over the entire farm. This has been shown to work with other pests in tree fruit where growers have treated partial but the majority of acreage for reasons of cost savings. In order to verify this for Oriental beetle a revision in methods could include more of a "checkerboard" treated/non-treated layout with large plots and traps and sample locations in the center of each plot. However, because previous research has shown that mating disruption works, and this work demonstrated population reduction, more efforts should be given to the availability of the mating disruption product.