Assessment of Biocontrol 

Possibilities for Japanese Beetle

Animal and Plant Health Inspection Service

September 1, 2020

Petty et al., 2012.

Agency Contact

Plant Epidemiology and Risk Analysis Laboratory

Science and Technology

Plant Protection and Quarantine

Animal and Plant Health Inspection Service

United States Department of Agriculture

1730 Varsity Drive, Suite 300

Raleigh, NC 27606
September 1, 2020 1

Assessment of Biocontrol Possibilities for Japanese Beetle 

USDA has supported biocontrol efforts against Japanese beetle since 1920, importing 49 natural 

enemies of Japanese beetle and related scarabs in hopes of attaining long-term control of the pest 

(Clausen and King, 1927; Potter and Held, 2002). Of the nine insects selected for introduction 

from Japan and Korea in the 1920s (Clausen and King, 1927), three parasitoids– one fly and two 

wasps– have established in limited areas of the United States and received additional attention 

over the years (McDonald, 2020; Potter and Held, 2002). USDA’s participation in programs to 

expand the ranges of these insects has been inconsistent and poorly documented, but we provide 

a brief summary below. 

The winsome fly, Istocheta aldrichi1, parasitizes Japanese beetle adults and was introduced to 

the Northeastern United States in 1922 (Cappaert and Smitley, 2000; Clausen and King, 1927; 

O’Hara, 2014). The winsome fly appears to have established in the Northeast after its 

introduction, but its life cycle is not well synchronized with Japanese beetle there (USDACPHST, 2005). The fly is also established in other infested states and has recently been 

introduced to Colorado (McDonald, 2020).

Two parasitoid Tiphia wasps– T. vernalis and T. popilliavora– that are established in the United 

States attack larvae (Potter and Held, 2002). Tiphia vernalis was introduced in 1925, and by 

1953, it had established in 15 states (Cappaert and Smitley, 2000). Adults of these wasps require 

sources of pollen and nectar to thrive (McDonald, 2020). However, floral resources are 

uncommon and difficult to maintain on airport grounds at levels that can support local control of 

Japanese beetle (Lewis, 2020). Like the winsome fly, T. vernalis is currently being introduced to 

Colorado (McDonald, 2020). 

USDA’s use of insects for biological control of Japanese beetle has been largely unsuccessful. 

On the other hand, decades of research on a microsporidian pathogen, Ovavesicula popilliae, 

suggest that it would be an effective biological control organism for long-term population 

management of Japanese beetle on airport grounds. 

Ovavesicula popilliae causes a chronic, debilitating disease in Japanese beetle hosts (Hanula and 

Andreadis, 1990). In areas with established populations of O. popilliae, adult females produce 

fewer eggs and larvae are less likely to survive through the winter (Smitley et al., 2011). Both 

grubs and adults can become infected, and if grubs survive, they can carry the pathogen into 

adulthood (Hanula and Andreadis, 1990). Once established in an area, O. popilliae is spread to 

new hosts by the beetles themselves, either by the release of spores from dead larvae in the soil 

or in excrement from adults (Petty, 2013).

1 Clausen first reported this species as Centeter cinerea Aldrich (Clausen and King, 1927). 
September 1, 2020 2

With the cooperation of local airport authorities, PPQ is currently seeding spores of the pathogen 

at airports across the regulated states and monitoring establishment. This effort started in 2017 

with six airports in five states but has now expanded to 11 airports in eight states (Figure; Lewis, 

2020). The pathogen has been recovered at some of these airport introduction sites (Rentschler, 

2020; USDA-APHIS, 2018). 

Japanese beetle CFWG continues to support research on developing this promising long-term 

management option, and further support is likely to be fruitful.

Figure. Ovavesicula popillae year of initial release at airport sites (data: Lewis, 2020).

Our review of the Japanese beetle program revealed that local beetle outbreaks can make 

safeguarding a challenge in some years (e.g., Moore, 2020; Simon and Johnson, 2020); therefore, 

keeping beetle abundances below outbreak numbers on airport grounds could be an effective 

way to safeguard flights over the long term. Biological control could potentially achieve this, but 

implementing a biological control program on airport grounds requires the cooperation of airport 

authorities or landscape managers who are not currently involved in the Japanese Beetle 

Program. 

The pathogen Ovavesicula popilliae can effectively reduce Japanese beetle populations once it 

has established. Japanese beetle populations at early O. popilliae introduction sites in Michigan 

are now so low that trapping adult beetles is difficult (Lewis, 2020). At one Michigan field site 
September 1, 2020 3

where the pathogen has been well-established since 2008, at least 76.5 percent of infected larvae 

do not survive overwintering (Piombino et al., In press). The combined effects of larval mortality 

and reduced female egg production are estimated to reduce Japanese beetle populations by 40 

percent each year (Piombino et al., In press). A successful biological control program could 

greatly reduce the risks of transporting Japanese beetles to the protected states. Establishment is 

a slow process but achieving this level of pest management is ideal.

PPQ has been releasing this pathogen at airports since 2017, and early results are promising 

(Lewis, 2020). However, seeding the pathogen requires burying infected beetle carcasses in 

grassy areas, which requires the cooperation of local airport authorities who manage airport 

grounds. Additionally, a formal environmental assessment of O. popilliae introduction has not 

yet been conducted, and some airport authorities might also be hesitant to participate in an 

experimental program (Lewis, 2020). Our interviews found that communication with landscape 

managers and obtaining permission from airport authorities can sometimes be an obstacle to 

implementing this program (Lewis, 2020; Simon and Johnson, 2020). Unlike carriers, airport 

authorities are not directly impacted by the Japanese beetle quarantine, and they may not 

consider beetle control a priority. 

Airports that can successfully establish O. popilliae could potentially reduce their beetle numbers 

enough that annual regulation is no longer necessary. This can be a valuable safeguarding tool, 

as outbreaks seem to lead to increases in incursions. Creating outreach materials that can help 

convince airport authorities and landscape managers to participate in the program might help get 

more airports involved in the program.

Literature Cited

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70th Annual Michigan Turfgrass Conference Proceedings Volume 29, Lansing, 

Michigan.

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(Korea) and their introduction into the United States. USDA Department Bulletin No. 

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