Leucism in Lepidoptera

Albinism and leucism are rare in Lepidoptera. If you google “Albinism and Leucism in Lepidoptera” you’ll find thousands of photos of mammals, birds, and reptiles, but only a scattering of leps, some of which are white species, not leucistics. The obvious exception is a white luna moth, which is normally green. But the photo is labeled “Albino,” while the dark ocelli stand out on all four wings. It is a leucistic. Leucism is caused by recessive alleles that don’t produce the normal pigments. Albinism is an extreme case of this in which all of the alleles are dysfunctional.

I found a Vanessa cardui that is partially leucistic, feeding with hundreds of normal morphs on Chrysothamnus bushes. I show it here with a normal form below.

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Siricids, Crab Spiders, Mimetics! Oh, my!

This morning in the flower garden I found a Siricid, a horntail wasp, a large male, crawling slowly up and down the raceme of a flowering mint. Soon I discovered, beneath him, a second male of the same species, and they seemed to be in some sort of competitive ritual. But, whoa! The surprise is that the smaller male hasn’t moved much because…DSC04521.jpg

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Did you see it? After watching them for about three hours, during which time the larger one continued wandering up and down the stalk, I noticed that the smaller one was moving only very slightly. I didn’t realize it until I enlarged a photo afterwards. Then I went back for a better look. Yikes! A crab spider!DSC04518.jpg

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Crab spiders are generalist predators that roughly match their substrate, so they qualify as “aggressive mimics.” The phenomenon is also known as “mimesis” when the model is inanimate, or at least not another similar species. Background mimics or cryptic species are mimetics.

 

Baculite Mesa, Pueblo County, a great place for bugs and spiders.

Here’s a few photos and a short video of trying to coax a tarantula out of her burrow.

 

Baculites are fossil cephalopods that formed long rod-shaped “bones,” much like the inner shell of a modern squid. The largest ones may be several feet long, but here at Baculite Mesa they are mostly small specimens.DSC04123.jpg

Here is one of the several preying mantises we found, a male.DSC04128.jpg

And the group, working on the tarantula burrow. We found several at home, but not eager to step into the sunlight.DSC04105.jpg

Here is a mating pair of Phyciodes picta, a desert version of the foothill campestris. It seems to be common in Pueblo County. We found scores of them.DSC04119.jpg

And a whiptail lizard, apparently sleeping through our disturbances.DSC04129.jpg

And even birds, although besides the pond-side doves and killdeer, there were few. Here’s a rock wren, the best photo I could get as it kept moving.DSC04121.jpg

A Note on Aspen Ecology

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In 2004, the Catamount Biological Field Station published a research brief by Peter Marchand and Anne Havemann (http://www.catamountcenter.org/research-and-projects/research-briefs/phellinus-tremulae-and-nest-cavity-resources-in-the-upper-montane-forests-of-the-pikes-peak-region/) that reported that aspen tree holes are strongly favored over conifers in terms of nesting sites for birds. In a survey of montane breeding birds they found 14 cavity-nesting insectivorous bird species (29 pairs), all but two of which nested in aspen tree holes, even when conifer tree holes were available. They further discovered that 87.5% of the tree holes studied were visibly infected by Phellinus tremulae, a heart rot fungus that seems to be transmitted from tree to tree by birds, bats, and probably insects. This led Peter Marchand to embark on a separate study of the significance of Phellinus on the health of aspen stands at and around the Catamount Field Station. Marchand’s study was apparently never published, but the upshot was fascinating to me.

It all starts with an aspen tree hole, into which Phellinus fungus is introduced, probably by woodpecker beaks that have previously probed and hammered infected tree holes.

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http://www.featheredphotography.com/blog/2014/06/04/williamsons-sapsuckers-and-the-glory-hole-aspen/ Photo by Ron Dudley

The fungus makes the tree easier to excavate as time goes on, so tree hole inhabitants can find nesting spaces. The presence of hungry birds reduces the numbers of moth larvae that feed on aspen leaves. This is good for the aspen!

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Thus, aspen, indirectly, seem to benefit from having heart rot fungus to make the tree holes livable. Of course, too much fungus would threaten the whole aspen stand. But having some trees infected is apparently beneficial to the degree that they attract the insectivorous birds. Balance is everything. The 2004 study found that about 12% infection by heart rot fungus provides an adequate number of tree holes to host hungry birds to provide protection for the aspen stand.

Benefiting from a parasitic fungus seems unusual to me. It would be like finding that athlete’s foot attracts a beneficial microbe, so humans would maintain a significant infection rate to gain the benefit. Are there parallels in our species? I mean, we have mutualists galore. But what about “beneficial” parasites?

The first feedback loop is a simple relationship between aspen and the herbivores that defoliate and damage it. As moths increase, aspen decrease. Bad for the aspen!

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But, with the introduction of the Phellinus fungus, aspen find an indirect benefit due to the increase in tree holes and their nesting birds, which depress moth populations. Good for the aspen!

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Remember that the decrease in moths creates an increase in aspen. It might seem that since the nesting birds positively affect the aspen, they would positively affect the fungus, the tree holes, and themselves. So what prevents a runaway, reinforcing loop for the tree-hole-nesting birds? I imagine, predators:

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This balancing set of effects seems to create a dynamic advantage to all species involved, and maintains ecosystem health.

Williams Alumni at The Nature Place

What a great week at The Nature Place near Florissant, Colorado. Thanks to all the Williams alumni for being interesting people engaged in studies of geology and natural history. See the post below this one for an update on our rabbit bot fly. But first, here are a few photos. Remember the anicia checkerspot?Anicia checkerspot

And, of course, the blue columbine from above the snowfields on Horseshoe Mountain.Blue columbine

And the 50+ elk across the stream below the cirque.Elk at Horseshoe Mtn

And Parry’s primrose, one of the most photographed flowers in the tundra.Parry' Primrose

And meanwhile, back at the lodge, Caripeta aequaliaria, the red girdle moth, hiding under the eaves.Snowia montanaria

And this little mountain bluebird juvenile on Wilkerson Pass.W bluebird juv

Thanks for a great week! See you all in 2019? If I’m not in a wheelchair.

 

The Female Rabbit Bot Fly

What th—? A Rabbit Bot Fly? Really??

Bot Fly, Cuterebra, family Oestridae, probably a rabbit bot

Today on Shelf Road in Fremont Co., Sam Peck, a veteran Blackhawk helicopter pilot and one of the Nature Place Staff, brought me the most amazing insect I’ve seen in years. Mystified at what it might be, I posted it on Arthropods Colorado Facebook group. Within an hour or two, I had about thirty comments, among which was an identification to genus and family: Alejandro Estrada identified it as a bot fly, genus Cuterebra, family Oestridae. Eric Eaton, entomology generalist who knows almost everything with six legs, further identified it as a rabbit bot, based in part on the red in the eyes. OMG. Then Prof. Boettner from UMass went still further, calling it Cuterebra lepusculi, and female based on the wide gap between the eyes. He verified that only the females have the red eye spots, and said that they fade with time in museum specimens. Unbelievable. They attack mainly cottontail rabbits. Other commenters noted how cute it is, but still others found this revolting, as bot flies are parasites that lay eggs under your skin, where the larvae hatch and cause an inflamed canker that eventually ruptures to allow the hideous (but cute) parasite to fly away. Although this particular specimen was not capable of flight, Prof Boettner assures me that once this thing sits for 24 hours or so, it will fly like its house is on fire, and will lay eggs in rabbit burrows.

Prof. Boettner’s last email on this subject states, “Hi Sam. Say hi to the Williams College gang for me. I should mention that although bots have short lives, females can lay over a thousand eggs in that short 10 day lifespan. And they only need one male and female egg to survive to keep the population stable. Amazing every rabbit isn’t infested. But they waste a lot laid in runways that never get in a host. That is a beauty that you found. One of the larger bots in the world. There is one in New Mexico that has yours beat in size. C. mirabilis. Nearly 2 inch long females! It uses black tailed jackrabbits as a host. And the male of that species has never been seen. So lots of mystery in the bot world.” He is doing DNA studies, and expressed the hope that I might have taken the specimen. Darn. So, maybe Sam Peck will go back up there and find me another one.

Bot Fly, Cuterebra, family Oestridae, probably a rabbit bot

Some viewers thought it might be a sculpture, a model. But it’s the real thing. After that, this moth larva seemed almost pedestrian.DSC03592