Tuesday, October 8, 2013

A ruthless killer battles fearsome parasitoids (and will probably lose)

I took this photo almost exactly one year ago - October 9, 2013. It is, or should I say, was the view from my office window. This shot wasn't taken from my window, but when I look down from my nearby office, this is pretty much the viewscape. I really detest vast grassy expanses of turf grass. Such a habitat is pointless, in many cases. Poaceous emerald deserts have their place in parks and other places where people gather outdoors for recreational pursuits. I accept that and have no quarrel with lawns where needed. But the country is overrun with nonnative grass. WAY too much. There is over 40 million acres of the stuff in the United States, which makes grass our biggest crop, supposedly. That's an area the size of Connecticut, Delaware, Kentucky (the Bluegrass State!), New Hampshire, and Rhode Island. Oh, we have to also add Yellowstone National Park to match the turfed over acreage of the lower 48 states.


The attendant loss of biodiversity - the plants and animals that make the world go 'round - is staggering. And most of it is completely and utterly unnecessary.

Here's nearly the same vista as the above photo, shot a few weeks back. I finally put my money where my mouth is insofar as the work complex's landscaping, and convinced the facility managers to install a prairie on the site of the aforementioned grassy wasteland. And bless their hearts, they did it! Many people - maybe most - are interested enough in biodiversity and doing good things for the environment that they will act in Nature's best interest when a chance presents itself. That's what happened here, and the results have been staggering. Keep in mind that the seeds of this prairie were not sown until May 21, of this year.

Major thanks go to Bob Kehres of Ohio Prairie Nursery for providing the seed, and all manner of expertise to help us get our prairie out of the ground.

Needless to say, I've been fascinated with the biological changes resulting from our little one-third acre prairie. At least once or twice a week I take the Canon outside and see what critters I can document. Where one year ago you could count on one hand the few tough animals that would utilize the lawn, it is now a veritable cornucopia of animal life.

The photo above shows a Yellow-collared Scape Moth, Cisseps fulvicollis, plundering nectar from a black-eyed susan. I made this image, and those that follow, this afternoon.

With the now abundant flowering plants providing nectar galore for pollinating insects, the predators have moved in to take advantage of the bounty. This Bold Jumping Spider, Phidippus audax (I think), glares at your narrator from atop a black-eyed susan. No dummy, the spider knows that lurking near a flower will soon produce a meal. It has been amazing to see how quickly the prey-predator food web has developed.

Last week I discovered jagged ambush bugs in the genus Phymata ensconced on the flowers of fleabane. I wrote about these recently, RIGHT HERE. Once again, I was surprised at just how rapidly these interesting insects found and colonized the brand spanking new prairie.

Anyway, sorry for the above deviations into turf grass bashing. It is this ambush bug, which I think may be Phymata fasciata (ID corrections always appreciated!), that I really want to discuss.

I strolled over to check the fleabanes where I had seen the ambush bugs last week, and quickly spotted one who had made a meal out of a tachinid fly. Note the ambush bug's long death-dealing proboscis, firmly injected into the fly's abdomen. The bug will slowly - and with great pleasure, I am sure - suck out the liquefied innards of the fly, leaving behind a desiccated husk.

This is all cool enough, but WAIT! A third insect lurks, to the right of the drama, on the ray flowers of the fleabane. It is truly tiny - so small that I didn't notice it in the field as I fixated on capturing images of the ambush bug. It wasn't until I downloaded the pictures and reviewed them that I saw the six-legged third wheel.

Who is it, and what might it be doing? My first thought was that it is a fly, and was perhaps waiting for an opportunity to drop its eggs on the fly carcass. Maybe its larvae would use that as a host. Those thoughts were quickly dispelled with a closer look - the elfin onlooker is actually a wasp!

This little wasp is too small for even my Canon's 100 mm macro, although I might have done somewhat better had I noticed the thing in the field and took direct aim. Ah well, live and learn.

Now that its identity (I think) has been established as a wasp, it's a bit easier to speculate about what is going on. The world is full of tiny parasitoid wasps that lay their eggs on all manner of insect hosts, and I figured that's what this wasp was scheming to do. A bit of searching around revealed a wasp known as Telenomus phymatae, and I wonder if that's this critter. It is a parasitoid of jagged ambush bugs, but not the adults. It seeks out freshly laid eggs of the ambush bug, and injects its eggs into the ambush bug eggs. The wasp grubs hatch first, within the host eggs, and eat them. So, if the wasp is indeed Telenomus phymatae, it is probably loitering around the ambush bugs awaiting the deposition of some eggs. Ironically, the tachinid fly is also a parasitoid, laying its eggs on some insect victim. What goes around comes around, and we've got a lot of paybacks being dealt out in this photo.

The overarching message of this post is this: plant diversity, especially native plants, spawns extraordinary animal diversity. Even right under our noses, in highly urbanized landscapes, in prairies that were planted only four and a half months ago.

GO NATIVE, and be sure to attend the 2014 Midwest Native Plant Conference.


Unknown said...

That is really great that you were able to get that change made. I wish other office parks would consider doing similar things.

Diana said...

Hadn't been up to Fountain Square lately...the prairie really looks great!

Bonnie said...

I love this blog. I learn something new with each post--like the word poaceous.

Mary Huey said...

A new bug to watch for -- ambush bug!

Jennifer said...

That's so awesome you prompted the planting of prairie and removal of grass. WOO WOO! :):)

At our little 3.5 acre property, the desire for mowing is something we continually deal with from peeps - "Hey, do you need me to come brush hog that field for you?" We're working on spreading the wonders of native plants in Morrow County. We will see. :)

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