Guess the Pest! Week #20 & 21 Answer: Trissolcus japonicus

Bill Cissel, Extension Agent – Integrated Pest Management;

Congratulations to Greg Hawn (week 20 winner) and to Joseph Streett (week 21 winner) for correctly identifying the insect as Trissolcus japonicus and for being selected to be entered into the end of season raffle for $100 not once but five times. Everyone else who guessed correctly will also have their name entered into the raffle. Click on the Guess the Pest logo to participate in this week’s Guess the Pest challenge!

Guess the Pest Week #20 – 21 Answer: Trissolcus japonicus
Bill Cissel, Extension Agent – Integrated Pest Management, Joe Kaser, Research Associate, USDA-ARS Beneficial Insects Introduction Research, and David Owens, Extension Entomologist

Trissolcus japonicus, a tiny wasp commonly referred to as the Samurai wasp, is an egg parasitoid of the invasive brown marmorated stink bug (BMSB). This particular species is native to Asia and has been in quarantine since 2007 and under evaluation for potential release as a classical biological control agent. In 2014, wild populations of Trissolcus japonicus, slightly different from the ones that were in quarantine, were detected in Beltsville, MD and since, additional discoveries have been made throughout the region, including Washington, D. C., Virginia, West Virginia, Pennsylvania, New Jersey, Ohio, and Delaware. It is believed that Trissolcus japonicus may have hitchhiked a ride in a BMSB egg mass that was on plant cargo shipped from Asia, but it is difficult to say exactly how it got here. In fact, it appears that the samurai wasp has hitchhiked here more than once!

A single Trissolcus japonicus female is capable of parasitizing an entire BMSB egg mass which typically contains ~28 eggs. When the male parasitoids emerge, they wait on the egg mass for the females to emerge so they can mate. They are capable of having up to ten generations per year.

To help with reducing BMSB populations in Delaware, we partnered with some of the folks at the USDA Beneficial Insects Introduction Research Laboratory in Newark, DE to redistribute Trissolcus japonicas throughout the state. When I share that we are releasing a parasitic wasp to help with BMSB control, the first reaction that I typically get is, “Will it sting me?” If you look at the photo with some wasps on the dime, you will understand why this is not a concern. Hopefully, this tiny wasp will live up to its name as the Samurai wasp and do its part in controlling BMSB.

Fun Entomology Fact: A female Trissolcus japonicus will chemically mark the BMSB eggs that she laid eggs in and defend them against other parasitoids.

Here is a link to a very informative fact sheet from UF on Trissolcus japonicus: