Tetrastichus julis–Parasitoid of Cereal Leaf Beetle

Biocontrol Agent Factsheet

Tetrastichus julis is a tiny parasitoid wasp that attacks the pest (cereal leaf beetle). When T. julis populations are large enough, they can control more than 25-90% of cereal leaf beetle.

Overview

Pests Targeted: Cereal Leaf Beetle (Oulema melanopus)
Pest Stage: Larvae in their second or third instar
Commercially Available? No
Scientific Name: Tetrastichus julis
Biocontrol Agent Type: Parasitoid

Close-up photo of a 4 mm black wasp laying eggs in a larva of cereal leaf beetle. It is standing on the larvae with its ovipositor inserted. — Tetrastichus julis adult wasp is stinging and laying eggs inside a cereal leaf beetle larva. Photo by Sebastian Markus Ederer-University of Idaho

Common Names

None

Relative effectiveness

When T. julis populations are large enough, they can control more than 25-90% of cereal leaf beetle. Reduce the use of insecticides and leave refuge areas (where pesticides are not used) to allow the parasitoid to build in populations.

Where to use

Field crops - small grains

About Tetrastichus julis

Tetrastichus julis is a tiny parasitoid wasp that only attacks the pest (cereal leaf beetle) and not humans or pets. The adult wasp will lay an average of five eggs into each cereal leaf beetle (CLB) larva during the second or third instar (developmental stage) of the larvae (May-June in New York State). When the wasp larva emerges from its egg (inside the CLB larva), it will feed on the inside of the pest larva until the CLB pupates in the soil, killing the pest in the pupal stage. Tetrastichus julis over-winters as a larva in the pupal case of the pest and will emerge in the spring and early summer the following year. Because of this life cycle, T. julis will not reduce populations of CLB in the current season, but will reduce the number of CLB larvae the following year.

Native/Non-native: Non-native
Preferred climate: arid, Humid, Wet, Temperate, Mediterranean, Sub-tropical, cold tolerant
Region: Throughout North America.
Established: Yes
Where established: Released across North America in the 1960’s to control cereal leaf beetle, and is established throughout North America.

Tetrastichus julis Appearance

Tetrastichus julis is a tiny black wasp (about 4 mm long). Its eggs and maggots are yellowish and about 2-3 mm long, but you will not see them unless you slice up a cereal leaf beetle larva.

Tetrastichus julis adult wasp is stinging and laying eggs inside a cereal leaf beetle larva.

Dissected cereal leaf beetle larvae with a circle and label showing where the T. julis eggs are

Dissected cereal leaf beetle larvae exposing five, very small, orange, oval-shaped T. julis eggs that were inside one of the larvae.

Tetrastichus julis Lifecycle

Adult
Egg Laying
Larval Development
Pupation and Overwintering

T. julis life cycle. (1) A parasitoid as an adult. (2) A parasitoid on top of a CLB larva. The CLB is round and yellow, with a goopy sludge on top (representing the fecal shield it makes to protect itself). The wasp is laying eggs in the larva. (3) Yellow beetle larva with six small orangish tan T. julis larvae developing inside the cereal leaf beetle larva. (4) Pupation and overwintering of T. Julis. The CLB's pupa case looks like soil mixed with soil sediment and pebbles. Six T. Julis pupa are inside — Tetrastichus julis life cycle. Illustration by Hannah Tolz

Adult
Tetrastichus julis emerges as an adult in the spring.

Egg Laying
During May and June, adult T. julis lay eggs inside cereal leaf beetle larvae, specifically targeting those in their second and third instar stages.

Larval Development
The T. julis larvae develop inside the cereal leaf beetle larva, feeding on their host until they are ready to pupate.

Pupation and Overwintering
By July, T. julis pupate within the cereal leaf beetle larva, which dies as a result. The parasitoids then overwinter inside the pupal case of their host in the soil.

How to Use Tetrastichus julis

Biocontrol category: Classical - released once and persists

Pest stage: Larvae in their second or third instar (developmental stage) are attacked by this parasitoid, but the pest is not killed until it reaches its pupal (resting) stage in the soil.

Mode of action: Parasitoid - larvae of T. julis feed on and eventually kill the cereal leaf beetle.

Conservation: attract and protect from the surrounding environment

Risk: This biocontrol agent does not infect or sting anything but the host pest (cereal leaf beetle).

Commercially available: No

About Cereal leaf beetle (Oulema melanopus)

Both the adult and larvae of the cereal leaf beetle feed on the surface of the leaf, though larvae do most of the damage. Larvae feeding damage appears as whitish strips parallel to the veins of the leaf. Because they remove the surface tissue, this area of the leaf is unable to photosynthesize, thus reducing the yield of grain. When populations are high, the larvae can damage the flag leaves, which are very important for grain development.

A slug-like dark brown insect larva with a black head on a green grass-like leaf.

Larva (immature stage) of the cereal leaf beetle feeding on the upper surface of a wheat leaf.

Close-up picture of what looks like a blade of grass with whitish strips running lengthwise along the leaf.

Damage to a wheat leaf caused by feeding from cereal leaf beetle. Both the adult and larvae of the beetles feed on the surface of the leaf.

Learn more about Tetrastichus julis

Agriculture and Agri-Food Canada. Field crop and forage pests and their natural enemies in Western Canada–Tetrastichus julis (pdf). Agriculture and Agri-Food Canada p. 130.
Roberts, D. and Walenta, D. L. 2012. Integrated pest management (IPM) for the cereal leaf beetle in Washington State. Washington State University.
Stehr. F. W. 1970. Establishment in the United States of Tetrastichus julis, a larval parasite of the cereal leaf beetle. Journal of Economic Entomology 63(6): 1968–1969, https://doi.org/10.1093/jee/63.6.1968

Authors

Ken Wise
Senior Extension Associate, NYS Integrated Pest Management

Jacob Leeser
Extension Aide, NYS Integrated Pest Management

Amara Dunn-Silver
Senior Extension Associate, NYS Integrated Pest Management

Date: July 2022

References

Agriculture and Agri-Food Canada. Field crop and forage pests and their natural enemies in Western Canada- Tetrastichus julis. Agriculture and Agri-Food Canada p. 130..
Cumming, J. Wise, K. and Dunn, A. 2019. Cereal leaf beetle biocontrol project underway NYS IPM Program-Cornell University.
Eigenbrode, S.; Foote, N.; UI, and Abatzoglou J. 2013. Cereal leaf beetle under projected Pacific Northwest climates, https://www.reacchpna.org/sites/default/files/AR3_5.1.pdf University of Idaho Annual Report
Harcourt, D., Guppy, J., & Ellis, C. (1977). Establishment and spread of Tetrastichus julis. (Hymenoptera: Eulophidae), a parasitoid of cereal leaf beetle in Ontario. The Canadian Entomologist, 109(3), 473-476.
Philips, C.R., Herbert, D.A., Kuhar, T.P., Reisig, D.D., Thomason, W.E., and Malone, S. (2011). Fifty years of cereal leaf beetle in the U.S.: An update on its biology, management, and current Research. Journal of Integrated Pest Management. 2. 10.1603/IPM11014.
Stehr. F. W. 1970. Establishment in the United States of Tetrastichus julis, a larval parasite of the cereal leaf beetle. Journal of Economic Entomology 63(6): 1968–1969,
Roberts, D. and Walenta, D. L. 2012. Integrated pest management (IPM) for the cereal leaf beetle in Washington State (pdf). Washington State University.
Walenta, D. 2014. Integrated pest management for the cereal leaf beetle (pdf). Oregon State University Extension.
Cárcamo, H. 2014. Biological control at its best, using the T. julis wasp to control the cereal leaf beetle (pdf). Agriculture and Agri-Food Canada.

Photos and Illustrations

Tetrastichus julis adult wasp is stinging and laying eggs inside a cereal leaf beetle larva. Photo taken by Sebastian Markus Ederer-University of Idaho
Eggs of T. julis. Photo by Jaime Cumming—NYSIPM
Life cycle illustration by Hannah Tolz—NYSIPM