Evaluation of New Approachesfor Management of Japanese Beetlesin Highbush BlueberriesRufus IsaacsZsofia SzendreiJohn C. WiseSUMMARY. The Japanese beetle, Popillia japonica, can be a pest ofhighbush blueberries because of direct feeding on berries and leaves,and the risk of contaminating harvested fruit. To determine where bee-tles are most abundant and whether cultural controls have potential foruse against P. japonica in blueberry, soil was sampled for grubs during2001 and 2002 in and around fifteen blueberry fields. Densities ofRufus Isaacs is Assistant Professor and Small Fruits Extension Specialist, ZsofiaSzendrei is Graduate Student, and John C. Wise is Research Specialist and Director ofthe Trevor Nichols Research Complex, Department of Entomology, Michigan StateUniversity, East Lansing, MI 48824 USA.Address correspondence to: Dr. Rufus Isaacs, Department of Entomology, Michi-gan State University, East Lansing, MI 48824 (E-mail: [email protected]).This research was supported by the USDA-CSREES Crops at Risk program, Pro-ject GREEEN, and the Michigan Blueberry Growers Association. The authors thankKeith Mason, Nikhil Mallampalli, and Ann Hanley for assistance with this research.They also acknowledge Dave Trinka of Michigan Blueberry Growers Association andthe Michigan blueberry growers who made this work possible by providing access totheir fields. Mention of these products does not constitute an endorsement over othersimilar products.[Haworth co-indexing entry note]: “Evaluation of New Approaches for Management of Japanese Beetlesin Highbush Blueberries.” Isaacs, Rufus, Zsofia Szendrei, and John C. Wise. Co-published simultaneously inSmall Fruits Review (Food Products Press, an imprint of The Haworth Press, Inc.) Vol. 3, No. 3/4, 2004,pp. 349-360; and: Proceedings of the Ninth North American Blueberry Research and Extension WorkersConference (ed: Charles F. Forney, and Leonard J. Eaton) Food Products Press, an imprint of The HaworthPress, Inc., 2004, pp. 349-360. Single or multiple copies of this article are available for a fee from TheHaworth Document Delivery Service [1-800-HAWORTH, 9:00 a.m. - 5:00 p.m. (EST). E-mail address:[email protected]].http://www.haworthpress.com/web/SFR 2004 by The Haworth Press, Inc. All rights reserved.Digital Object Identifer: 10.1300/J301v03n03_12 349overwintering P. japonica were greater under permanent sod outsidefields than in the soil between the rows. When grub density inside thefields was compared between clean-cultivated rows and those with sod-ded row middles, cultivated rows had significantly lower grub densitiesthan those with sod. Bioassays with pyrethrum insecticides against adultbeetles indicated their potential for removal of beetles from bushes justprior to harvest. An integrated strategy including elimination of suitablehabitat by cultivation and use of chemical controls to remove beetles be-fore harvest is under development for reducing populations and mini-mizing contamination of blueberry by this pest.[Article copies availablefor a fee from The Haworth Document Delivery Service: 1-800-HAWORTH.E-mail address: <[email protected]> Website: <http://www.HaworthPress.com>  2004 by The Haworth Press, Inc. All rights reserved.]KEYWORDS. Japanese beetle, Popillia japonica, blueberry, culturalcontrol, integrated pest managementINTRODUCTIONThe Japanese beetle, Popillia japonica Newman (Coleptera: Scara-baeidae) was introduced accidentally from Japan to the eastern coast ofNorth America in 1916 (Fleming, 1972). Since its arrival in southernNew Jersey, this mobile insect has gradually increased in geographicdistribution. P. japonica has become established as far west as Minne-sota and Kansas (Anonymous, 2000) and has been sporadically de-tected and eradicated in some western US states (Fleming, 1972; Potterand Held, 2002). Adult beetles can cause extensive feeding damage to abroad range of ornamental and fruit plants by feeding on their leavesand fruit (Fleming, 1972; Potter and Held, 2002), and this species hasbecome a major pest of managed turf due to the preference of larvalstages (grubs) for feeding on grass roots (Vittum et al., 1999). Beetlescan cause feeding damage on leaves and ripe berries of highbush blue-berries, Vaccinium corymbosum L. if other plants are not present. How-ever, it is the presence of adult beetles on plants at harvest that is ofgreatest concern, due to the risk of contamination of harvested berries.Japanese beetles were first detected in Michigan in the early 1930snear Detroit and even though early eradication programs included leadarsenate applications at 1000 pounds per acre, the beetle has increasedin range and is now found throughout the lower tier of Michigan(Cappaert and Smitley, 2002), including some regions with highbush350 Proceedings of the Ninth North American Blueberry Researchblueberry production. Insecticide applications continue to be the foun-dation of management strategies for Japanese beetle in blueberries andmany other fruit crops, as growers strive to meet the market’s demandfor contamination-free fruit. Broad-spectrum insecticides are effectiveagainst beetles that are treated directly (Wise and Isaacs, unpublisheddata), but most of these products have long pre-harvest intervals creat-ing a potential for immigrating beetles to re-infest fields as residue ac-tivity declines. Over 70% of Michigan’s 7,285 ha (18,000 acres) ofblueberry is harvested mechanically, and because beetles can be presenton bushes at the time of harvest, strategies that eliminate the risk ofadult beetles contaminating the fruit are needed.Conditions in and around crop fields can favor development of thisinsect if primary requirements for Japanese beetle population develop-ment are met (Vittum et al., 1999). Ground covers of seeded grass or thenaturally-invading mix of grass and broadleaved weeds are commonlyused in blueberry fields to maintain soil structure, provide conditionsfor agricultural machinery to drive across during wet conditions, and re-duce soil erosion. Japanese beetle grubs feed on the roots of grasses andsome broadleaved weeds (Crutchfield and Potter, 1995) and blueberryfields often have areas with these ground covers within and around thebushes. In addition, sufficient soil moisture for development of firstinstar grubs is present in many commercial blueberry fields in July andAugust because of natural rainfall and irrigation, and soil temperaturesabove ⫺9.4°C in