Sumac Gall Aphids – Master Tricksters

I was walking around in a cemetery with a friend who spotted these strange balls on staghorn sumac leaves:

20160730-3I figured they were a galls, which are swellings in plants caused by parasitic fungi, bacteria, nematodes, or in most cases, insects and mites. It’s always fun to crack open galls to find out what is living inside. These turned out to be full of aphids! I wasn’t expecting that.

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When I got home I found out that these are sumac gall aphids (Melaphis rhois). Like all galling parasites they have a very clever trick. Through some highly specialized chemical secretions or physical modification they force their host plant to grow their food and shelter for them. It’s a pretty sweet deal for the aphids. These galls start when a female aphid lays a single egg in a sumac leaf, when it hatches the gall starts forming and that single aphid reproduces asexually within the gall. So all the aphids within the gall are identical clones of one another.

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But it gets trickier. Later in the year winged females fly off to start a new colony on moss. This radical host switching behavior has been happening for over 48 millions years and is one of the longest lasting plant-insect relationships ever documented. At some point the clonal colonies on moss produce males and females which mate and it’s these mated females that fly off to lay eggs in the spring.

As species have evolved and gone extinct and the continents have shifted, these aphids have been in an annual three-way dance with trees and mosses which gave them all the food and shelter they needed. Only recently a precocious bipedal primate showed up who found their own ways to get plants to produce food and housing for them. They’re pretty clever too but they have a tendency to destroy all their prefered habitats. We’ll see if they can keep it up for 48 millions years.

 

Colorful Symbioses

Lichen are a classic example of symbiosis. A fungus teams up with an algae or a cyanobacteria, the fungus use their digestive powers to extract nutrients from just about anything while also creating a nice home for the algae or cyanobacteria to turn sunlight into energy. They give and take, and together they can thrive in places where little else survives. Well, it turns out there is another player. Recent research shows that many lichens also contain a third symbiont, a unicellular yeast! The yeast produces an acid that may protect the whole threesome from attack by other microbes. (See this great article about how natural history observations led to this discovery). As much as we often focus on clashes in nature, the predator and prey, the host and parasite, the fierce competitors, it’s easy to forget that the origins of eukaryotic life (the group of organisms that contains all plants, animals, fungi) was made possible by a symbiosis between two different types of bacteria. And studies using new molecular tools are increasingly finding elaborate webs of microbial symbioses across the tree of life, and not a single bird, flower, or beetle could survive without these complex relationships. I honor of these new discoveries, here are some beautiful products of lichenous partnerships I’ve photographed in Michigan, Ontario, South Carolina, and Arizona:201312182015041220150524-320150524-220150528-220150528-320150528-4201508172014032820150528-520150311-220151008-5

Phenomenal Fen

Recently Chad Zirbel posted a photo of a stunning orange lily that I just had to see for myself. He directed me to a nearby high-quality prairie fen. This habitat is flooded with calcium-rich groundwater which selects for a unique community of plants, many of which are adapted to this specific habitat.

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The spongy peat and dense communities of sedges where unlike anything I’d seen before.

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I got a bit lost though before I made it to the fen, and when I was wandering around the surrounding forest I found this incredible fungus. It looks a lot like the bleeding-tooth fungus (Hydnellum peckii)but with clear secretions instead of red. I suspect this is a related species but I’m not sure. It was visited by lots of small flies and wasps, I like thinking of what this oozing structure would be like to a 2 mm long insect.

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I also found this spiky tachinid fly calming visiting flowers, a much more charming place to hang out than the innards of some other animal where it came from. Most tachinids are internal parasites and judging by the size of this fly I’d guess it came out of a vertebrate of some sort.

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I found the Michigan Lily (Lilium michiganense)! This species is actually found throughout much of the midwest and southern US and is commonly cultivated. Still, it was a stunning sight to see this one erupting out of the dense mat of prairie grasses.

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Swamp milkweed (Asclepias incarnata) is the water-loving cousin of the common milkweed that is commonly seen along roadsides.

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Black-eyed Susan (Rudbeckia hirta) is not really a wetland plant but it seemed to be doing just fine in this soggy habitat. There were many more plants that were surely more rare and unique to this habitat but I couldn’t help but be attracted to the ones with the showy flowers. If I had more natural history knowledge of the species I am sure I would have appreciated the community more.

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There was one wetland specialist that I recognized though, purple pitcherplant (Sarracenia purpurea). They only grow in highly alkaline or acid environments, places where most plants have trouble acquiring enough nutrients. They make up for it by feasting on insects that are lured into their water-filled leaves.

Marvelous Milkweed Herbivores

All plants are involved in an evolutionary battle with herbivores, where plants evolve various traits that deter herbivores and then herbivores evolve the ability to eat them again. This evolutionary struggle has raged on for over 400 millions years, contributing to the massive diversification of both plants and the wide range of herbivores that eat them. So much so that plants and herbivores make up a majority of the diversity of life on earth, at least among organisms bigger than microbes. In some cases this evolutionary struggle results in plants and herbivores that have all sorts of fascinating traits and behaviors.

Milkweeds (genus Asclepias) evolved an impressive array of defenses against herbivores, including toxic cardenolides that stop insects’ hearts, gooey latex which gums up their mouths, and obnoxious hairs which make munching through leaves a hassle. These defenses work really well because most insects don’t even bother trying to eat milkweeds at all. But, unfortunately for the milkweeds, and fortunately for fans of really awesome insects, there are a bunch of herbivores from all across the insect tree of life that evolved to feed on milkweeds and only milkweeds, and they’ve gotten really good at it. Most of them are brightly colored to warn predators of their toxicity (called aposematic coloration). And they are toxic because, amazingly, they can tolerate the toxic cardenolides in the milkweeds and then incorporate them into their tissues. An exceptionally clever adaptation that turns a plant’s defense into a tool to deter predators.

In a recent walk around Sleepy Hallow State Park outside of Lansing, Michigan, I saw a bunch of these milkweed specialist. First is a one we are all familiar with, the caterpillar of the monarch butterfly:

Monarch (Danaus plexippus)Monarch (Danaus plexippus)Monarch (Danaus plexippus)

The fruits of some of the milkweeds were coated with large milkweed bugs (Oncopeltus fasciatus):

Large milkweed bug (Oncopeltus fasciatus)Large milkweed bug (Oncopeltus fasciatus)

Then I found one of my favorites, the swamp milkweed beetle (Labidomera clivicollis):

swamp milkweed beetle (Labidomera clivicollis)swamp milkweed beetle (Labidomera clivicollis)

There are two aphid species that commonly feed on milkweeds, the bright yellow oleander aphid (Aphis nerii), which is actually and introduced species in North America, and the more drab-colored milkweed aphid (Aphis asclepiadis). Both are commonly tended by ants who collect sugary honeydew they excrete and then, in some cases, protect them from predators.

oleander aphid (Aphis nerii)

milkweed aphid (Aphis asclepiadis)I found one more caterpillar that feeds on milkweed, the delightfully fuzzy milkweed tussock caterpillar (Euchaetes egle):

milkweed tussock caterpillar (Euchaetes egle)milkweed tussock caterpillar (Euchaetes egle)

There is also one more really rad milkweed herbivore I didn’t find, the red milkweed beetle (Tetraopes tetrophthalmus), but check out some these great photos of them by Ellen Woods (1, 2, 3, 4).

As the sun set I was excited that I found so many fascinating and photogenic animals during a short walk near the lake.

20150912-20Thinking about the perennial struggle between plants and herbivores reminds me of the last line in Darwin’s Origin of Species “from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved”, which so succinctly summarizes how fulfilling it is to carefully observe, understand, and appreciate the marvelous diversity of life which surrounds us.

Three Jumping Spider Shots

Here are three looks at a stunning jumping spider I found on a tall reed near the Savannah River in South Carolina. First with a white background showing the huge fuzzy forelegs and red-spotted abdomen, then a close-up portrait with the metallic green chelicerae, then a wide angle macro shot with a horse pasture, trees, and rainbow in the background :)

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Life and Death

I found abundant signs of life and death in a recent walk through the woods

jumping spider with midge

Jumping spider eating a midge

Zelus sp.

Assassin bugs stalking

Zelus sp.

fly carpenter ant

Carpenter ants dragging a still living fly back to their colony

green bottle fly

Blow fly waiting for something to die

racoon nest

Squeaks from a hollow tree trunk

baby raccoon with mom

Raccoon cubs squabbling and breastfeedingskunk cabbageAnd skunk cabbage emerging after a long winter