Imagine Vici (*insert Italian hand gestures*).
Vici is an aphid, a small insect in the same order as cicadas, stink bugs and bed bugs. Aphids’ prey are plants. Specifically, the plant sap, a very valuable resource. Sap is mostly made of water and sugar and is transported via the sieve tubes.
Plant sap is rife with sugar, but it lacks the amino acids aphids need to grow into even more formidable plant menaces. To compensate for this deficiency, aphids consume plant sap in astronomical portions to imbibe sugar, just to get sufficient protein.
However, plant sap is a limited food source for the aphid. To keep from starving, aphids have evolved a symbiotic relationship with a bacterium called Buchnera aphidicola, which helps to provide essential amino acids. Buchnera is an endosymbiont that cannot survive independently outside of the aphid.
To feed, Vici uses her stylet, a long, flexible needle. She slowly worms it into the tissue, between the plant’s cells, until she pierces one of those sieve tubes. Because the sap is under so much pressure, Vici doesn’t even have to suck it out of the plant. She simply opens a valve in her head and lets the pressure push the sap through her digestive system.
While we will come back to her excretory products in a wink, for now, you should know that plants don’t appreciate being punctured and sipped. So, they try to defend themselves. One defence is the sap itself. Irony, amirite.
To see how that works, let’s hypothetically hook up some other insect’s digestive tract to a steady stream of sap. When that sap touches the insect’s cells, its high sugar content encourages the water in the cells to come out by osmosis – remember that? no? doesn’t matter – exactly like salt encourages water to come out of a slug.
In simpler words, the highly sugary sap leeches out the water from inside the insect cell. The more sap that passes through the insect, the more water it loses. Until eventually, the insect shrivels up and dies.
Vici’s gut, however, is packed with an enzyme named sucrase. Sucrase takes two molecules of sucrose and converts them into one molecule of fructose and one of this three-unit sugar.
Vici burns the fructose for energy, leaving the three-unit-sugar behind. How does that help her? The more molecules of sugar that are dissolved in the sap, the more water it can suck out of Vici’s cells. By reducing the number of molecules of sugar in the sap, Vici reduces its ability to suck water out of her cells. Plant sap neutralized! That means Vici can feed for days, getting all the energy she needs to reproduce. Excess or unused sugar from plant sap is safely snugged away in the aphid’s widening rectum to be used later.
Now, you might be thinking what’s the point of this entire article. Short story; it’s a highly detailed poop joke (I may use the term “joke” liberally. It’s artistic license). Long story?
Some aphid species have an incredible life cycle. For example, the green peach aphid. During fall, males and females mate, and the females lay eggs. In spring, when the eggs hatch, all the nymphs that emerge are female. When those females reach maturity, they don’t lay eggs. Instead, they give birth to live young ones…
that are clones of themselves and already pregnant with…
So, these female aphids have two generations of baby aphid clones forming inside themselves at the same time. Scientists call this telescopic development. Basically, this means that aphids can make more of themselves fast — there can be 20 generations within a single season — and that means lots of aphid poop.
Finally, I know.
Vici can poop her entire body weight every two hours, making her one of the most prolific poopers on the planet. Some aphid populations can produce hundreds of kilograms of poop per acre.
Be that as it may, aphid poop is not like our poop. Chemically, it’s not all that different from sap; it’s a clear and colorless sweet, syrupy liquid.
You might already know it by a different name: honeydew.
Now, other species love honeydew. Emphasis on love. Some species of ants love it so much they herd and defend entire aphid colonies. In return, ants get to caress the back of an aphid’s abdomen to initiate the release of a steady supply of sweet honeydew. They can drink this directly from the aphids’ butts.
Bottom’s up, I guess!
Humans love honeydew, too. Several Native American tribes used to harvest it from tall reeds and make it into cake. And some species of bee make honey from honeydew, which humans then harvest and eat. So, plants make the sap, which is eaten and pooped out by aphids, regurgitated by bees, harvested by humans, and dolloped into a cup of Earl Grey tea.
Ah, the circle of life. (Nants ingonyama bagithi baba!)
– Stuti, Delhi Public School, Noida1 Like