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| Parasitized Adult Japanese Beetles were Released in Betty's Yard in 2020 Notice the Small Brown Pupa |
Recently on my Punch List by Betty Cahill Facebook page I shared information from the Minnesota Landscape Arboretum about finding evidence that the beneficial predator fly, commonly known as the Winsome Fly has been found in their arboretum. This is great news. The comments and shares from my FB post were numerous.
So this is a timely opportunity to further explain the importance of this discovery and how it relates to us and our battle against pest Japanese beetles in Denver Metro areas, Boulder, Pueblo and other communities along the Front Range.
First, if you aren't familiar, or wish to know more about Japanese beetles, their life cycle, how to manage, etc., click here for much more info. than I'll cover in this blog. I have written other blog posts on JBs (usually one or two a year), so just type in Japanese beetle on the search tab and read more.
This is my first blog where I've gone deeper into the subject of JB biocontrols.
HERE'S THE IMPORTANT TAKE AWAY -
It isn't common knowledge in Denver and most of Colorado that two professionals in Colorado began releasing three biocontrol agents along the Front Range starting back in 2015 to increase Japanese beetle mortality. This good news needs to get out there!
By biocontrols I'm referring to natural enemies and/or infectious pathogens which can cause injury or death to pest insects. These biocontrols are strictly approved and regulated by state authorities so they don't cause harm or have any other unintended consequences to our soil and insect populations which include pollinators.
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| photo from University of Maine Extension |
The three biocontrols that have been released include -
1. A fungal spore pathogen that harms both Japanese beetle larvae and adults. The spore is called Ovavesicula Popilliae. Say that five times fast, not easy. No worries, you just need to know that it is effective and it IS established in some of the areas where it has been released.
2. A parasitic* wasp called Tiphia vernalis targets overwintering JB larvae (also called white grubs). They are NOT established at the time of this writing. This wasp is also called the spring tiphia.
3. The parasitic* fly called Winsome Fly botanically named Istocheta aldrichi targets adult Japanese beetles. They are NOT established at the time of this writing. Winsome Flies are also called tachinid flies.
For a better visual of these three biocontrol agents, please click here. These are twenty slides from my PowerPoint class on Japanese beetle management. There were limited releases of additional Ovavesicula Popilliae in 2021.
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| Parasitized JB Larva, Photo from CNGA |
*What does it mean to Parasitize a pest insect?
Parasitic insects such as the Tiphia vernalis and Istocheta aldrichi are both in the group of parasitic or predator insects that lay eggs ON a target insect. In this case, it would be either on an adult Japanese beetle (Fly) or overwintering Japanese beetle larvae (Wasp). The female fly and wasp lay an egg on the target and once the egg grows to the larval stage, it uses the target insect as food, which, as you can guess, kills the pest-target insect.
Other types of parasitic insects lay eggs inside a host insect. For a good visual and description of this type, click here.
The
Minnesota Landscape Arboretum touched on an important point about the
parasitic Winsome Fly, which is probably applicable to the parasitic
wasp. Weather conditions must cooperate very well in timing for both predator insects to develop from their pupae stage into adults and emerge to target or parasitize Japanese beetle adults and larvae. And,
there must be adequate food sources growing in our gardens (pollen and
nectar) to sustain both the fly and wasp to be nourished and stay around
to do their work. I also cover this information in the PP slides.
Thanks to Mother Nature and the whole coordination of predator needing the correct prey at the correct time - the Winsome Fly has a one-year life cycle just like Japanese beetles (same for Istocheta aldrichi, the wasp). Once the egg from the Winsome Fly reaches the larva stage, it begins eating the JB for food. Then it pupates and spends until the following spring somewhere on the ground near the parasitized beetle until it emerges from its pupa as an adult for the cycle to begin again. The wasp pupa remain in the soil under grass turf near the eaten JB larva until emergence as an adult wasp the following year to again target JB larvae.
Both the predator fly and wasp have not been confirmed as established near any of the release sites or surrounding areas. I hear whispers about the fly possibly being around ... nothing FIRM as of this writing, stay tuned.
Please click and read more about these outstanding biocontrols mentioned in the links below. Remember that we must plant plants that both the fly and the wasp need for nourishment in their adult stage. This fall is a good time to get a jump on some of these tiny flowered plants and peonies to set the table for them.
There are plans for future releases. If you would like to support Dr. Cranshaw's biological program on Japanese beetles, please click here. Below the dollar boxes click on the arrow in the search box and type in the number 18153 - Insect Research for Horticultural Crops. Please click or fill in your dollar amount and continue with the prompts to complete your donation and taking part in reducing Japanese beetle numbers. Thank you!
Resources -
Developing Japanese Beetle Biological Control Programs ... read this first!
Japanese Beetle Biological Control Release
Winsome Fly Release in Betty's Garden, July 2020 Betty's YouTube videos
Ovavesicula Popilliae Journal Article
Plant Flowers to Encourage Beneficial Insects
The Spring Tiphia: a Natural Enemy of the Japanese Beetle
The Winsome Fly and Why We Love This Bug
What is a Beneficial Parasite?
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