Wednesday, 23 November 2011

A Native Ladybug AND Ant-mimic?! No way!

It's not all that often when I find a ladybug (or to be more correct, lady beetle, since it's in the order Coleoptera and not Hemiptera) that isn't the invasive multicolored Asian lady beetle. So when I do, I get pretty excited. I get pretty disappointed when I see invasive organisms dominating the landscape, but when some interesting natives that I've never encountered before pop up, I'm apt to jump up and down in joy (ask anyone who's been out in the field with me).

Last month on a botany trip around campus, our group stopped to examine a black locust (Robinia pseudoacacia). My attention quickly wandered away from me and I found myself examining the other plants around the black locust, leading me to find some arthropods (woohoo!). One looked like an ant, but my previous experience during the summer taught me not to be too certain, so I caught it and pulled out my hand lens to take a closer look.

Imposter!

Not an ant, but rather an ant-mimic! This is actually a jumping spider (Family Salticidae), Synemosyna formica. It looks like the spider has three segments of its body like an insect, head-thorax-abdomen, but since it's a spider, it only has two: a cephalothorax and an abdomen. In order to look more like an ant, the cephalothorax is constricted, giving it the illusion of having three body segments. Now that's some fine Batesian mimicry!

The second arthropod I found hanging around the underbrush was one of our native lady beetles: Psyllobora vigintimaculata. Let's break down that etymology! Psyllo is Greek for flea, and it is quite small; bora is Greek for northern, referring to its habitat distribution. (This is the only species in the genus that you can find in the northeast.) The specific epithet vigintimaculata simply means 20 spotted. If we put it all together, we learn that this species is a small lady beetle that has a northern distribution (though it also occurs in the southern US) and has 20 spots. That's some useful information to know.

Not the largest lady beetle you'll find...

It wasn't exactly the easiest insect to spot, but it was crawling around on the same leaf as the spider, so it was easy to catch both of them. Now, that picture doesn't really help you understand what this beetle looks like....sure, it's white with black spots, maybe a touch of orange, and small, but come on. A hand lens isn't going to cut it. To the dissecting microscope!

Now that's what I'm talking about!

Now we can make more sense of what it looks like. You can see the 20 spots, the texture of the shell, and what it looks like underneath. The anatomy can only tell us so much about the species, so to learn more about how it lives, let's turn to a paper published in 2009 by Sutherland and Parrella (citation can be found at the end of this post). It turns out that this lady beetle (and the others in its subfamily Halyziini) isn't predacious like most other lady beetles, nor does it eat leaves: it feeds on various mildew fungi. These are fungi in the order Erysiphales, which cause powdery mildew diseases in plants, hence their common name. 

Powdery mildew disease is of economic importance in agriculture, and is the main reason why Sutherland and Parrella undertook their study. They found that P. vigintimaculata is a generalist that feeds upon a range of fungi species, and that its density in the environment increased with a greater density of mildew. That's pretty good news for an integrated pest management plan, according to their paper.

They also had a figure showing the beetle's life cycle, which follows. Note that in this study, they used a subspecies, Psyllobora vigintimaculata taedata, so that's what is being referred to. 

Figure 1 from Sutherland and Parrella. (Click to enlarge)

If you see any of those crawling around on your plants, then you've got this species. Note that the adults overwinter under leaves and other secluded spaces (and warmer areas....well, as warm as you can get during winter), so you could be finding them in early Spring. 

Just in case you notice some plants showing signs of mildew disease, look around for this little lady beetle. It's another way in which insects are working in our favor without asking anything in return. Isn't that great? Be sure to keep this in mind the next time you encounter multicolored Asian lady beetles seeking shelter in your home and remember: not all lady beetles are a nuisance!

Citation:
Sutherland, Andrew M.; Parrella, M. P. “Biology and Co-Occurrence of Psyllobora vigintimaculata taedata (Coleoptera: Coccinellidae) and Powdery Mildews in an Urban Landscape of California.” Annals of the Entomological Society of America, v. 102 issue 3, 2009, p. 484-491.

Saturday, 19 November 2011

Hackberry: The Teenage Years

I was going through some of my photos from this past summer (preparing to organize and identify them), when I came across a picture of a tree with some very interesting bark.


I had a vague feeling of recognition when I took this picture, but I couldn't quite pin it down. After being a teaching assistant for a botany class this semester, however, I remembered what it was the second time around: American hackberry (Celtis occidentalis).

What's the easiest way to remember this tree? Definitely the bark: it's gnarled and warty, with furrows. As the tree gets older, it gets more warty and just a tad bit smoother. It hasn't reached this stage yet, so I would call this tree a teenager. 

The leaves are serrate (they have little teeth on the edges), and are alternatively arranged on the stem.


American hackberry is found in the West and Midwest, and is relatively common in Ohio. When its leaves fall off in the autumn, you can sometimes find galls on the leaves caused by a Psyllid insect (it's related to cicadas and aphids). Due to these little insects, the leaves can become as warty as the bark! For more information about the galls, check out the University of Nebraska-Lincoln Extension site.

Interestingly enough, this tree has been in my backyard for a while now and I never noticed it before. If you haven't found a theme from my blog yet, consider this: get out there and start observing! There's still so much to explore.

Friday, 11 November 2011

Chronicles of Ignorance: Wheel Bug Edition

Regular readers should know by now: I freaking love wheel bugs.

Click that picture to enlarge it, sit back, and really look at it for a while. There's no way you'll ever convince me that's not one of the most beautiful creatures in the world.

So when I catch wind of the wheel bug being talked about in a negative light, I try to set the record straight. Unfortunately, this time, I could not set the record straight. This link will take you to the website for a local news station serving Pittsburgh, WTAE. The video on the page talks about the wheel bug and how one resident discovered one in her yard and was a little frightened. 

Rather than trying to dissuade her of her fears, however, the news team proceeds to FLIP OUT. In what can only be described as an egregious example of shoddy journalism dipped in a vat of ignorance, the video goes on a two minute rampage warning about the dangers of the wheel bug and showing pictures of it to random people on the street, delighting in their faces of horror. 

If you're a fan of insects and nature, or can at least appreciate their merits, you should be offended and disgusted. The video makes no attempt to cast the bug in a positive light, focusing on the slight chance that it can bite people. It's obvious that this was simply a filler story to scare people about the next "insect menace," after the bed bugs of this past summer. 

A news organization should have more integrity than this, focusing on education over fear mongering. It's a disservice to the general public and should not be tolerated. Allowing media like this to be broadcast will only increase the general public's lack of knowledge and misconceptions about the enormous importance of insects. 

In pursuit of remedying this, I have contacted the news station to express my discontent. If you feel the need to follow suit, just click here. The only information they request from you is your name and e-mail. Just make sure to tell them that you would be more than happy to assist them in setting the record straight, or you can redirect them to me.