This Bug Is Drinking Your Milkshake


A meadow frog urinates so much that it can choke itself. Fortunately, the Philaenus spumarius beetle, which is about the size of a Tic Tac, has a butt catapult that regularly blasts globules of liquid waste into the air and safely away from its body.

“On this tiny, tiny scale ballistics gets really complicated,” said Philip GD Matthews, associate professor of comparative physiology in the University of British Columbia’s department of zoology. “But they can throw quite far,” he said, and clarified that “quite far” here means two to four inches.

Urinary powers of frogs are well understood among entomologists. But the insects’ sucking abilities, which have long puzzled scientists, turned out to be far more impressive, according to an article on the feeding mechanisms of meadow frogs published Wednesday. Proceedings of the Royal Society B.

Froghoppers are common and known to spread throughout Europe and North America. some bacterial diseases among plants. They urinate almost constantly because insects feed on pure xylem sap; this liquid is so devoid of nutrients that it is sometimes sipped and drunk continuously for up to 24 hours.

Most plant sap-drinking insects drink phloem, a sugary liquid in plant veins that is easy to obtain because it moves with positive pressure, that is, squirts out of a plant stem after being pierced by their mouthparts. In contrast, the xylem is driven by negative pressure—its vessels are actually pulled inward—making the watery fluid unbearably difficult to absorb. Dr. Such negative pressures exist within unbroken containers of xylem, where water is drawn from the roots to the leaves and evaporates into the atmosphere, Matthews said.

Dr. Matthews, a graduate student she recommended, Elisabeth Bergman, and an undergraduate volunteer, Emma Green, studied the insects’ morphology and tested their metabolic abilities to demonstrate the frogs’ suction power. weeds near their labs.

The researchers took Micro-CT scans of the heads of adult frogs and analyzed the morphology of their cibarial pumps, a structure that allows them to draw xylem sap into their faces. Like a plunger in a syringe, a diaphragm is pulled by the muscles to increase the volume of the chamber and draw in the xylem sap. Because froghoppers must rhythmically pull on this diaphragm to suck, the nose-like structure between their eyes, called the post-clypeus, is strong enough to accommodate all these muscles.

Dr. “It’s like a big bicep on their head,” Matthews said.

Using the size of the frogs’ cibarial pumps, the researchers calculated how much negative pressure the insects could create inside their heads. Their calculations suggested that frogs could generate up to 1.6 megapascals, a pressure greater than the tension inside many xylem vessels.

This showed that the frogs were able to absorb much more than previously believed. Dr. “If the beetles were atop the Statue of Liberty torch, they could stick a low-to-the-ground straw into a glass of water and suck it up quite happily,” Matthews said. He added that frogs would still be fine even a few feet above the torch.

After calculating the insects’ powerful suction, the researchers wanted to confirm that the action did not use more energy than it gained. To test this, they placed frogs and a size pea plant in airtight acrylic chambers to measure how much carbon dioxide the insect produced after 30 minutes of slurry sap.

While the insects are still visible to the human eye, magnified videos of the frogs’ faces revealed how much facial muscles moved during feeding.

Dr. “Suddenly there’s an insect sitting there doing nothing, its nose seems to be wagging like crazy,” Matthews said, referring to the frog’s post-clypeus.

The pea plant was grown hydroponically, with bare roots hung in a nutrient solution. This made it easy to replace the solution with polyethylene glycol, a liquid with even stronger negative pressure than the nutrient solution. Dr. Matthews compared drinking polyethylene glycol to a cyclist cycling up a hill rather than on flat ground. The researchers thought the frogs would slow down when faced with even more resistant fluid. The frogs, however, managed to maintain the same absorption rates despite a rapidly increasing metabolic rate.

Alberto Fereres, an entomologist from Madrid, said the study helps explain how P. spumarius can feed on “very negatively stressed” plants such as rain-fed olives and vines.

Metabolic measurements showed that insects can gain more energy than they expend, even when sucking full-gas xylem sap. “It’s their existence,” said Dr. Matthews. “Drinking, filtering, peeing and pumping.”

While this process may be extreme on a frog’s side, a single sucking insect is most likely undetectable by any plant. Unless, of course, there’s an infestation, in which case copious bits of liquid waste being swept up his ass can even look like rain.


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