Camel Crickets and the Dust Seeds of Parasitic Plants

A common way for plants to disperse their seeds is to entice animals to eat their seed-bearing fruits – a strategy known as endozoochory. Undigested seeds have the potential to travel long distances in the belly of an animal, and when they are finally deposited, a bit of fertilizer joins them. Discussions surrounding this method of seed dispersal usually have birds and mammals playing the starring roles – vertebrates, in other words. But what about invertebrates like insects? Do they have a role to play in transporting seeds within themselves?

Certain insects are absolutely important in the dispersal of seeds, particularly ants. But ants aren’t known to eat fruits and then poop out seeds. Instead they carry seeds to new locations, and some of these seeds go on to grow into new plants. In certain cases there is an elaisome attached to the seed, which is a nutritious treat that ants are particularly interested in eating. Elaisomes or arils have also been known to attract other insects like wasps and crickets, which may then become agents of seed dispersal. But endozoochory in insects, at first, seems unlikely. How would seeds survive not being crushed by an insect’s mandibles or otherwise destroyed in the digestion process?

camel crickets eating fruits of parasitic plants (via New Phytologist)

While observing parasitic plants in Japan, Kenji Suetsugu wanted to know how their seeds were dispersed. Many parasitic plants rely on wind dispersal, thus their seeds are minuscule, dust-like, and often winged. However, the seeds of the plants Suetsugu was observing, while tiny, were housed in fleshy fruits that don’t split open when ripe (i.e. indehiscent). This isn’t particularly unusual as other species of parasitic plants are known to have similar fruits, and Suetsugu was aware of studies that found rodents to be potential seed disperers for one species, birds to be dispersers of another, and even one instance of beetle endozoochory in a parasitic plant with fleshy, indehiscent fruit. With this in mind, he set out to identify the seed dispersers in his study.

Suetsugu observed three achlorophyllous, holoparisitic plants – Yoania amagiensis, Monotropastrum humile, and Phacellanthus tubiflorus. While their lifestyles are similar, they are not at all closely related and represent three different families (Orchidaceae,  Ericaceae, and Orobanchaceae respectively). All of these plants grow very low to the ground in deep shade below the canopy of trees. Air movement is at a minimum at their level, so seed dispersal by wind is not likely to be very effective. Using remote cameras, Suetsugu captured dozens of hours of footage and found camel crickets and ground beetles to be the main consumers of the fruits, with camel crickets being “the most voracious of the invertebrates.” This lead to the next question – did the feces of the fruit-eating camel crickets and ground beetles contain viable seeds?

Monotropastrum humile via wikimedia commons

After collecting a number of fecal pellets from the insects, Suetsugu determined that the seeds of all three species were “not robust enough to withstand mastication by the mandibles of the ground beetles.” On the other hand, the seeds passed through the camel crickets unscathed. A seed viability test confirmed that they were viable. Camel crickets were dispersing intact seeds of all three parasitic plants via their poop. The minuscule size of the seeds as well as their tough seed coat (compared to wind dispersed seeds of similar species) allowed for safe passage through the digestive system of this common ground insect.

In a later study, Suetsugu observed another mycoheterotrophic orchid, Yoania japonica, and also found camel crickets to be a common consumer of its fleshy, indehiscent fruits. Viable seeds were again found in the insect’s frass and were observed germinating in their natural habitat. Seutsugu noted that all of the fruits in his studies consumed by camel crickets are white or translucent, easily accessible to ground dwelling insects, and give off a fermented scent to which insects like camel crickets are known to be attracted. Camel crickets also spend their time foraging in areas suitable for the growth of these plants. All of this suggests co-evolutionary adaptations that have led to camel cricket-mediated seed dispersal.

Yoania japonica via wikimedia commons

Insect endozoochory may be an uncommon phenomenon, but perhaps it’s not as rare as we once presumed. As mentioned above, an instance of endozoochory by a beetle has been reported, as has one by a species of cockroach. Certainly the most well known example involves the wetas of New Zealand, which are large, flightless insects in the same order as grasshoppers and crickets and sometimes referred to as “invertebrate mice.” New Zealand lacks native ground-dwelling mammals, and wetas appear to have taken on the seed dispersal role that such mammals often play.

Where seeds are small enough and seed coats tough enough, insects have the potential to be agents of seed dispersal via ingestion. Further investigation will reveal additional instances where this is the case. Of course, effective seed dispersal means seeds must ultimately find themselves in locations suitable for germination in numbers that maintain healthy populations, which for the dust seeds of parasitic plants is quite specific since they require a host organism to root into. Thus, effective seed dispersal in these scenarios is also worth a more detailed look.

Further Reading:

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For more stories of seed dispersal check out the first issue of my new zine, Dispersal Stories.

Botany in Popular Culture: Close It Quietly by Frankie Cosmos

Frankie Cosmos – the stage name for Greta Kline and also the name of her band – is not a new thing but was new to me in 2019. Their music is classified broadly as indie rock or indie pop, and could easily be placed in a number of subgenres. I, however, consider it punk. The songs are short, emotionally raw, unconventionally structured, simply arranged, and independently produced. That’s punk enough for me. Their most recent album, Close It Quietly, is easily my top pick for best album of 2019. The reason I’m saying this here on a blog about plants is because plants are featured in some of the lyrics. But it’s more than that really.

Quite often plants find their way into the lyrics of songs. They are, after all, great subject matter for all kinds of art. The special thing to me about the lyrics of Close It Quietly isn’t so much that plants get mentioned, but the sentiments that surround the references and the lessons learned from them. It may just be personal bias, but to me the plant references are more than just cursory. They come from a place of connection and personal relationship. Plants have things to teach us, and when we are open to it – which is often during challenging times in our lives – we can hear their lessons.

Trees receive the bulk of the plant references on this album. Like the song “Trunk of a Tree,” for example, in which Greta sings, “You’re the trunk of a tree / silent, filled with clarity.” That’s no surprise though. As David George Haskell writes in his book, The Songs of Trees, “To listen to trees, nature’s great connectors, is therefore to learn how to inhabit the relationships that give life its source, substance, and beauty.” There is great wisdom in trees. Confiding in or consulting with them can help bring clarity to a moment or feeling. This doesn’t have to mean anything weird – just being among trees and observing them in a reflective way will do the trick.

What follows is a list of some of the songs on Close It Quietly along with their plant references and some thoughts about them.

“41st”

This song is pretty fitting for the start of a new year, with the first line asking, “Does anyone wanna hear the 40 songs I wrote this year?” Looking back, maybe it was a crummy year. Perhaps you weren’t treated well, or maybe someone in your life didn’t turn out to be who you thought they were. There may be some comfort in knowing that you’re not the only one going through such things. Glancing up at the trees, Greta sings, “I look at the branches and hold a mirror up / They’re looking at me and say, ‘You don’t have a comb, do ya?'” The tangled branches of trees speak of past difficulties. As it turns out, we all have challenges that we’re trying to move past.

“A Joke”

We often find ourselves under pressures to be or act a certain way – to conform to some standard that was decided by someone else. Timelines created by other people direct our lives and tell us how or where we should be at a certain age or point in life. But, as Greta notes, “Flowers don’t grow in an organized way. Why should I?” It’s okay to be yourself, and there is no rush to become someone or something else.

“Rings (on a Tree)”

Sometimes we have to walk away from relationships, particularly when those relationships are not good for us. It’s never easy, but perhaps you’ll come to the realization that “it was wrong, so wrong / to try to hold on to a fallen tree / one that wouldn’t even look at me” or one that wasn’t “holding arms out lovingly.” It doesn’t mean that person wasn’t or still isn’t meaningful to you in some way. It’s just that it’s time to move on.

“This Swirling”

In our worst moments we are “like a dandelion,” and “just a little bit of breath blows [us] apart.” Our lives feel as chaotic as the swirling of a dandelion fluff tumbling through the air. However, a closer look reveals that a dandelion seed in flight is actually more stable than we originally thought. Perhaps we can take some comfort in that.

More Botany in Popular Culture

2019: Year in Review

It’s the start of a new decade and the beginning of another year of Awkward Botany. As we’ve done in years prior, it’s time to look back at what we’ve been up to this past year and look forward to what’s coming in the year ahead. Thank you for sticking with us as we head into our eighth year exploring and celebrating the world of plants.

The most exciting news of 2019 (as far as Awkward Botany is concerned) is the release of the first issue of our new zine, Dispersal Stories. It’s a compilation of (updated) writing that originally appeared on Awkward Botany about seeds and seed dispersal and is the start of what I hope will be a larger project exploring the ways in which plants get around. Look forward to the second issue coming to a mailbox near you sometime in 2020.

Also new to our Etsy Shop is a sticker reminding us to always be botanizing, including while riding a bike. Stay safe out there, but also take a look at all the plants while you’re cruising around on your bike or some other human-powered, wheeled vehicle. Whether you’re in a natural area or out on the streets in an urban or rural setting, there are nearly always plants around worth getting to know.

This year we also started a Ko-fi page, which gives readers another avenue to follow us and support what we do. Check us out there if Ko-fi is your thing.

Buy Me a Coffee at ko-fi.com

We also still have our donorbox page for those who would like to support us monetarily. As always you can stay in touch with us by liking and following our various social media accounts (Facebook, Twitter, Tumblr, and our currently inactive, but that could change at any moment Instagram). Sharing is caring, so please be sure to tell your friends about Awkward Botany in whatever way you choose. We are always thrilled when you do.

Below are 2019 posts that are part of new and ongoing series. You can access all other posts via the Archives widget. 2019 saw a significant drop in guest posts, so if you’d like to submit a post for consideration, please visit our Contact page and let me know what you’d like to write about. Guest writers don’t receive much in return but my praise and adulation, but if that sounds like reward enough to you, then writing something for Awkward Botany might just be your thing. And while we’re on the topic of guest posts, check out this post I wrote recently for Wisconsin Fast Plants.

Happy Reading and Plant Hunting in 2020!

Inside of a Seed & Seed Oddities:

Podcast Review:

Poisonous Plants:

Tiny Plants:

Eating Weeds:

Using Weeds:

Drought Tolerant Plants:

Tea Time:

Field Trip:

Awkward Botanical Sketches:

Guest Posts: