Recent IPM Advances Using Parasitoids to Suppress Japanese beetle Populations Dr. R.C. McDonald, Symbiont Biological Pest Management Dr. M.G. Klein, ARS-USDA, ret.

Spring Tiphia - Attacks 3rd Instar JB/OB grubs; Food plants play a critical role in high parasitization rates (60% or more)

Chronology of Recent JB Parasitoid Research on the Spring Tiphia, Tiphia vernalis Rohwer: Parasitization rates for grubs in areas with food plants 60% or more. Considered by USDA researchers to be the most effective parasitoid over the entire range of JB Tulip Poplar found by RCM in NC as a nectar and mating site; allowed us to collect 100s of wasps easily for redistribution to other states infested with JB. USDA/State researchers found the Spring Tiphia to be specific to the Popillia/Exomala genera - none of this genera occurs naturally in the United States. Thus Spring Tiphia attacks 2 exotics and no natives. Spring Tiphia has NEVER been recorded attacking any native grub species - we have years of host testing data to support this. Recently (2004) found in every county in Connecticut (cold tolerant) Establishment of the Spring Tiphia in Sullivan, MO (Meramec State Park) from release of 100 females in 1999; JB populations here at lowest numbers since trapping started in see chart. Drs. Klein & McDonald have the resources and expertise to collect hundreds of Spring Tiphia for redistribution efforts to outbreak areas in the Midwest US for suppression activities, AND we have the expertise to follow up and evaluate these sites to document suppressive activities against populations of Japanese beetle.

Figure 1. Japanese beetle grub contour map, Meramec State Park, Sullivan, MO 6/20/03; n = 20 foot squared soil digs. Each isobar is 0.5 grub; therefore the highest grub count is near the fifth dig, at 5.5 grubs per square foot.

Table 1. Soil Surveys of one foot square samples at Meramec State Park for Life Stages of Japanese beetle and its larval parasite, the Spring Tiphia from Parasitization rates for Spring Tiphia vary from 10 to 20% total sample by year; actual rates on grubs is higher. Locale in Meramec State Park DateNumber of square foot soil samples 3 rd Insta r Grub Pupa e Adul t Tiphia Cocoon s Percent Parasitization W. Picnic21Apr Playground21Apr Central Picnic21Apr W. Picnic27May Central Picnic27May Central Picnic 27May W. Picnic20June Central Picnic20June Central Picnic20June Central Picnic18May Central Picnic2June

Istocheta aldrichi - fly likes cooler/wet areas; collect parasitized beetles with food lure; JB dies in 5 days

Chronology of Recent Developments with the Winsome Fly, a JB adult parasitoid, Istocheta aldrichi Mesnil Istocheta aldrichi (Japan) is specific to Jb: lays 90% of eggs on female beetles Parasitized beetles die within 5 days of oviposition by the fly. Parasitization rates are thus additive every 5 days. 1980s-1990s - Trapping work (USDA & NCDA) in Connecticut found high rates of adult beetle parasitization; see charts. We developed the ability to mass trap and redistribute Istocheta-parasitized JB cadavers for redistribution and establishment to novel areas, such as Northwestern North Carolina, Minnesota, and Michigan. Establishment of Istocheta aldrichi in NW NC in 2000 from releases made in 1997 and 1998; establishment of Istocheta in Michigan 2005; recovery of F2 Istocheta in Minnesota 2005 from releases made in 2003 and In NW NC during 2005, the Winsome fly has spread over more than 6 square miles and is effecting parasitization rates of 30 to 70% of female Jb.

This beetle is dead in 5 days! Thus parasitization rates are additive every 5 days.

Use of Parasitoids for IPM Program To Suppress JB Populations in High Risk Areas Spring Tiphia: Needs food plants Redistribute to areas of high JB quarantine risk Can redistribute 100s of wasps to selected locations 65% parasitization rate in favorable areas (food plants) Winsome Fly: Zone 6 or less Food Plants Important Redistribute 2 sequential years; need cadavers/year Trap about 10,000+/ year 21 to 70% of all female beetles parasitized