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.

• 1993- 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). • 2005 - 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 1987 - 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 1999-2005. 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

Date Number of square foot soil samples

3rd Instar Grub

Pupae

Adult

Tiphia

Cocoons

Percent

Parasitization

W. Picnic 21Apr99 9 13 0 0 0 0.0

Playground 21Apr99 9 1 0 0 0 0.0

Central Picnic 21Apr99 9 8 0 0 0 0.0

W. Picnic 27May99

9 5 0 0 0 0

Central Picnic 27May99

9 5 0 0 0 0.0

Central

Picnic

27May99

9 3 0 0 0 0

W. Picnic 20June00

20 1 1 2 1 20.0

Central Picnic 20June00

20 0 0 0 0 0

Central Picnic 20June03

20 1 17 4 3 12.0

Central Picnic 18May05

20 13 0 0 3 18.8

Central Picnic 2June05 20 14 2 2 2 10.0

Total # of Beetles Caught Each YearMeramec State Park, Sullivan, Mo.

155348

48925 50704

71051

143301

118661

45844 4461956735

44625

1420517456 17191

58097

4326035746

38393

432509

63587

83005

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

500000

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

#of Beetles100 Tiphia vernalis femalesreleased 1999

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 2004.

• 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 3000+ cadavers/year

• Trap about 10,000+/ year

• 21 to 70% of all female beetles parasitized